Bitmap/Read a PPM file: Difference between revisions
(Updated to work with Nim version 1.4; changed header parsing to conform to PPM specs; added integrity checks.) |
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proc header(f: File): tuple[width, height: Index] = |
proc header(f: File): tuple[width, height: Index] = |
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## Read the header and |
## Read the header and return the image width and height. |
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var state = waitingMagic |
var state = waitingMagic |
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for (token, lastInLine) in f.tokens: |
for (token, lastInLine) in f.tokens: |
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Revision as of 21:11, 24 October 2020
You are encouraged to solve this task according to the task description, using any language you may know.
Using the data storage type defined on this page for raster images, read an image from a PPM file (binary P6 prefered). (Read the definition of PPM file on Wikipedia.)
Task: Use write ppm file solution and grayscale image solution with this one in order to convert a color image to grayscale one.
Ada
<lang ada>with Ada.Characters.Latin_1; use Ada.Characters.Latin_1; with Ada.Integer_Text_IO; use Ada.Integer_Text_IO; with Ada.Streams.Stream_IO; use Ada.Streams.Stream_IO;
function Get_PPM (File : File_Type) return Image is
use Ada.Characters.Latin_1; use Ada.Integer_Text_IO;
function Get_Line return String is -- Skips comments
Byte : Character;
Buffer : String (1..80);
begin
loop
for I in Buffer'Range loop
Character'Read (Stream (File), Byte);
if Byte = LF then
exit when Buffer (1) = '#';
return Buffer (1..I - 1);
end if;
Buffer (I) := Byte;
end loop;
if Buffer (1) /= '#' then
raise Data_Error;
end if;
end loop;
end Get_Line;
Height : Integer; Width : Integer;
begin
if Get_Line /= "P6" then
raise Data_Error;
end if;
declare
Line : String := Get_Line;
Start : Integer := Line'First;
Last : Positive;
begin
Get (Line, Width, Last); Start := Start + Last;
Get (Line (Start..Line'Last), Height, Last); Start := Start + Last;
if Start <= Line'Last then
raise Data_Error;
end if;
if Width < 1 or else Height < 1 then
raise Data_Error;
end if;
end;
if Get_Line /= "255" then
raise Data_Error;
end if;
declare
Result : Image (1..Height, 1..Width);
Buffer : String (1..Width * 3);
Index : Positive;
begin
for I in Result'Range (1) loop
String'Read (Stream (File), Buffer);
Index := Buffer'First;
for J in Result'Range (2) loop
Result (I, J) :=
( R => Luminance (Character'Pos (Buffer (Index))),
G => Luminance (Character'Pos (Buffer (Index + 1))),
B => Luminance (Character'Pos (Buffer (Index + 2)))
);
Index := Index + 3;
end loop;
end loop;
return Result;
end;
end Get_PPM;</lang> The implementation propagates Data_Error when the file format is incorrect. End_Error is propagated when the file end is prematurely met. The following example illustrates conversion of a color file to grayscale. <lang ada>declare
F1, F2 : File_Type;
begin
Open (F1, In_File, "city.ppm"); Create (F2, Out_File, "city_grayscale.ppm"); Put_PPM (F2, Color (Grayscale (Get_PPM (F1)))); Close (F1); Close (F2);
end;</lang>
AutoHotkey
Only ppm6 files supported.
<lang AutoHotkey>img := ppm_read("lena50.ppm") ; x := img[4,4] ; get pixel(4,4) y := img[24,24] ; get pixel(24,24) msgbox % x.rgb() " " y.rgb() img.write("lena50copy.ppm") return
ppm_read(filename, ppmo=0) ; only ppm6 files supported { if !ppmo ; if image not already in memory, read from filename
fileread, ppmo, % filename
index := 1 pos := 1
loop, parse, ppmo, `n, `r
{
if (substr(A_LoopField, 1, 1) == "#")
continue
loop, {
if !pos := regexmatch(ppmo, "\d+", pixel, pos)
break
bitmap%A_Index% := pixel
if (index == 4)
Break
pos := regexmatch(ppmo, "\s", x, pos)
index ++
}
} type := bitmap1 width := bitmap2 height := bitmap3 maxcolor := bitmap4 bitmap := Bitmap(width, height, color(0,0,0)) index := 1 i := 1 j := 1 bits := pos
loop % width * height
{
bitmap[i, j, "r"] := numget(ppmo, 3 * A_Index + bits, "uchar")
bitmap[i, j, "g"] := numget(ppmo, 3 * A_Index + bits + 1, "uchar")
bitmap[i, j, "b"] := numget(ppmo, 3 * A_Index + bits + 2, "uchar")
if (j == width)
{ j := 1 i += 1 }
else
j++ }
return bitmap }
- include bitmap_storage.ahk ; from http://rosettacode.org/wiki/Basic_bitmap_storage/AutoHotkey</lang>
BBC BASIC
<lang bbcbasic> f% = OPENIN("c:\lena.ppm")
IF f%=0 ERROR 100, "Failed to open input file"
IF GET$#f% <> "P6" ERROR 101, "File is not in P6 format"
REPEAT
in$ = GET$#f%
UNTIL LEFT$(in$,1) <> "#"
size$ = in$
max$ = GET$#f%
Width% = VAL(size$)
space% = INSTR(size$, " ")
Height% = VALMID$(size$, space%)
VDU 23,22,Width%;Height%;8,16,16,128
FOR y% = Height%-1 TO 0 STEP -1
FOR x% = 0 TO Width%-1
r% = BGET#f% : g% = BGET#f% : b% = BGET#f%
l% = INT(0.3*r% + 0.59*g% + 0.11*b% + 0.5)
PROCsetpixel(x%,y%,l%,l%,l%)
NEXT
NEXT y%
END
DEF PROCsetpixel(x%,y%,r%,g%,b%)
COLOUR 1,r%,g%,b%
GCOL 1
LINE x%*2,y%*2,x%*2,y%*2
ENDPROC</lang>
C
It is up to the caller to open the file and pass the handler to the function. So this code can be used in Read image file through a pipe without modification. It only understands the P6 file format.
Interface:
<lang c>image get_ppm(FILE *pf);</lang>
Implementation:
<lang c>#include "imglib.h"
- define PPMREADBUFLEN 256
image get_ppm(FILE *pf) {
char buf[PPMREADBUFLEN], *t;
image img;
unsigned int w, h, d;
int r;
if (pf == NULL) return NULL;
t = fgets(buf, PPMREADBUFLEN, pf);
/* the code fails if the white space following "P6" is not '\n' */
if ( (t == NULL) || ( strncmp(buf, "P6\n", 3) != 0 ) ) return NULL;
do
{ /* Px formats can have # comments after first line */
t = fgets(buf, PPMREADBUFLEN, pf);
if ( t == NULL ) return NULL;
} while ( strncmp(buf, "#", 1) == 0 );
r = sscanf(buf, "%u %u", &w, &h);
if ( r < 2 ) return NULL;
r = fscanf(pf, "%u", &d);
if ( (r < 1) || ( d != 255 ) ) return NULL;
fseek(pf, 1, SEEK_CUR); /* skip one byte, should be whitespace */
img = alloc_img(w, h);
if ( img != NULL )
{
size_t rd = fread(img->buf, sizeof(pixel), w*h, pf);
if ( rd < w*h )
{
free_img(img);
return NULL;
}
return img;
}
}</lang>
The following acts as a filter to convert a PPM file read from standard input into a PPM gray image, and it outputs the converted image to standard output (see Grayscale image, Write ppm file, and Raster graphics operations in general):
<lang c>#include <stdio.h>
- include "imglib.h"
int main() {
image source; grayimage idest; source = get_ppm(stdin); idest = tograyscale(source); free_img(source); source = tocolor(idest); output_ppm(stdout, source); free_img(source); free_img((image)idest); return 0;
}</lang>
C#
Tested with this solution.
<lang csharp>using System.IO; class PPMReader {
public static Bitmap ReadBitmapFromPPM(string file)
{
var reader = new BinaryReader(new FileStream(file, FileMode.Open));
if (reader.ReadChar() != 'P' || reader.ReadChar() != '6')
return null;
reader.ReadChar(); //Eat newline
string widths = "", heights = "";
char temp;
while ((temp = reader.ReadChar()) != ' ')
widths += temp;
while ((temp = reader.ReadChar()) >= '0' && temp <= '9')
heights += temp;
if (reader.ReadChar() != '2' || reader.ReadChar() != '5' || reader.ReadChar() != '5')
return null;
reader.ReadChar(); //Eat the last newline
int width = int.Parse(widths),
height = int.Parse(heights);
Bitmap bitmap = new Bitmap(width, height);
//Read in the pixels
for (int y = 0; y < height; y++)
for (int x = 0; x < width; x++)
bitmap.SetPixel(x, y, new Bitmap.Color()
{
Red = reader.ReadByte(),
Green = reader.ReadByte(),
Blue = reader.ReadByte()
});
return bitmap;
}
}</lang>
Common Lisp
The function read-ppm-image reads either a P6 or P3 file depending on the file contents. The package description assumes that you have the Basic bitmap storage#Common Lisp package.
<lang lisp> (in-package #:rgb-pixel-buffer)
(defparameter *whitespaces-chars* '(#\SPACE #\RETURN #\TAB #\NEWLINE #\LINEFEED))
(defun read-header-chars (stream &optional (delimiter-list *whitespaces-chars*))
(do ((c (read-char stream nil :eof)
(read-char stream nil :eof))
(vals nil (if (or (null c) (char= c #\#)) vals (cons c vals)))) ;;don't collect comment chars
((or (eql c :eof) (member c delimiter-list)) (map 'string #'identity (nreverse vals))) ;;return strings
(when (char= c #\#) ;;skip comments
(read-line stream))))
(defun read-ppm-file-header (file)
(with-open-file (s file :direction :input) (do ((failure-count 0 (1+ failure-count))
(tokens nil (let ((t1 (read-header-chars s))) (if (> (length t1) 0) (cons t1 tokens) tokens)))) ((>= (length tokens) 4) (values (nreverse tokens) (file-position s)))
(when (>= failure-count 10)
(error (format nil "File ~a does not seem to be a proper ppm file - maybe too many comment lines" file)))
(when (= (length tokens) 1)
(when (not (or (string= (first tokens) "P6") (string= (first tokens) "P3"))) (error (format nil "File ~a is not a ppm file - wrong magic-number. Read ~a instead of P6 or P3 " file (first tokens))))))))
(defun read-ppm-image (file)
(flet ((image-data-reader (stream start-position width height image-build-function read-function)
(file-position stream start-position) (dotimes (row height) (dotimes (col width) (funcall image-build-function row col (funcall read-function stream))))))
(multiple-value-bind (header file-pos) (read-ppm-file-header file)
(let* ((image-type (first header))
(width (parse-integer (second header) :junk-allowed t)) (height (parse-integer (third header) :junk-allowed t)) (max-value (parse-integer (fourth header) :junk-allowed t)) (image (make-rgb-pixel-buffer width height))) (when (> max-value 255) (error "unsupported depth - convert to 1byte depth with pamdepth")) (cond ((string= "P6" image-type) (with-open-file (stream file :direction :input :element-type '(unsigned-byte 8)) (image-data-reader stream file-pos width height #'(lambda (w h val) (setf (rgb-pixel image w h) val)) #'(lambda (stream) (make-rgb-pixel (read-byte stream) (read-byte stream) (read-byte stream)))) image)) ((string= "P3" image-type) (with-open-file (stream file :direction :input) (image-data-reader stream file-pos width height #'(lambda (w h val) (setf (rgb-pixel image w h) val)) #'(lambda (stream) (make-rgb-pixel (read stream) (read stream) (read stream)))) image)) (t 'unsupported))
image))))
(export 'read-ppm-image) </lang> To read the feep.ppm file as shown on the description page for the ppm format use: <lang lisp> (read-ppm-image "feep.ppm") </lang>
D
The Image module contains a loadPPM6 function to load binary PPM images.
Delphi
Class helper for read and write Bitmap's and Ppm's
<lang Delphi> program BtmAndPpm;
{$APPTYPE CONSOLE}
{$R *.res}
uses
System.SysUtils, System.Classes, Winapi.Windows, Vcl.Graphics;
type
TBitmapHelper = class helper for TBitmap private public procedure SaveAsPPM(FileName: TFileName; useGrayScale: Boolean = False); procedure LoadFromPPM(FileName: TFileName; useGrayScale: Boolean = False); end;
function ColorToGray(Color: TColor): TColor; var
L: Byte;
begin
L := round(0.2126 * GetRValue(Color) + 0.7152 * GetGValue(Color) + 0.0722 * GetBValue(Color)); Result := RGB(L, L, L);
end;
{ TBitmapHelper }
procedure TBitmapHelper.SaveAsPPM(FileName: TFileName; useGrayScale: Boolean = False); var
i, j, color: Integer; Header: AnsiString; ppm: TMemoryStream;
begin
ppm := TMemoryStream.Create;
try
Header := Format('P6'#10'%d %d'#10'255'#10, [Self.Width, Self.Height]);
writeln(Header);
ppm.Write(Tbytes(Header), Length(Header));
for i := 0 to Self.Height - 1 do
for j := 0 to Self.Width - 1 do
begin
if useGrayScale then
color := ColorToGray(ColorToRGB(Self.Canvas.Pixels[i, j]))
else
color := ColorToRGB(Self.Canvas.Pixels[i, j]);
ppm.Write(color, 3);
end;
ppm.SaveToFile(FileName);
finally
ppm.Free;
end;
end;
procedure TBitmapHelper.LoadFromPPM(FileName: TFileName; useGrayScale: Boolean = False); var
p: Integer; ppm: TMemoryStream; sW, sH: string; temp: AnsiChar; W, H: Integer; Color: TColor;
function ReadChar: AnsiChar; begin ppm.Read(Result, 1); end;
begin
ppm := TMemoryStream.Create; ppm.LoadFromFile(FileName); if ReadChar + ReadChar <> 'P6' then exit;
repeat
temp := ReadChar;
if temp in ['0'..'9'] then
sW := sW + temp;
until temp = ' ';
repeat
temp := ReadChar;
if temp in ['0'..'9'] then
sH := sH + temp;
until temp = #10;
W := StrToInt(sW); H := StrToInt(sH);
if ReadChar + ReadChar + ReadChar <> '255' then exit;
ReadChar(); //skip newLine
SetSize(W, H);
p := 0;
while ppm.Read(Color, 3) > 0 do
begin
if useGrayScale then
Color := ColorToGray(Color);
Canvas.Pixels[p mod W, p div W] := Color;
inc(p);
end;
ppm.Free;
end;
begin
with TBitmap.Create do
begin
// Load bmp
LoadFromFile('Input.bmp');
// Save as ppm
SaveAsPPM('Output.ppm');
// Load as ppm and convert in grayscale
LoadFromPPM('Output.ppm', True);
// Save as bmp
SaveToFile('Output.bmp');
Free; end;
end. </lang>
E
<lang e>def chr := <import:java.lang.makeCharacter>.asChar
def readPPM(inputStream) {
# Proper native-to-E stream IO facilities have not been designed and
# implemented yet, so we are borrowing Java's. Poorly. This *will* be
# improved eventually.
# Reads one header token, skipping comments and whitespace, and exactly
# one trailing whitespace character
def readToken() {
var token := ""
var c := chr(inputStream.read())
while (c == ' ' || c == '\t' || c == '\r' || c == '\n' || c == '#') {
if (c == '#') {
while (c != '\n') { c := chr(inputStream.read()) }
}
# skip over initial whitespace
c := chr(inputStream.read())
}
while (!(c == ' ' || c == '\t' || c == '\r' || c == '\n')) {
if (c == '#') {
while (c != '\n') { c := chr(inputStream.read()) }
} else {
token += E.toString(c)
c := chr(inputStream.read())
}
}
return token
}
# Header require(readToken() == "P6") def width := __makeInt(readToken()) def height := __makeInt(readToken()) def maxval := __makeInt(readToken())
def size := width * height * 3
# Body # See Basic bitmap storage for the definition and origin of sign() def data := <elib:tables.makeFlexList>.fromType(<type:java.lang.Byte>, size) if (maxval >= 256) { for _ in 1..size { data.push(sign((inputStream.read() * 256 + inputStream.read()) * 255 // maxval)) } } else { for _ in 1..size { data.push(sign(inputStream.read() * 255 // maxval)) } }
def image := makeImage(width, height) image.replace(data.snapshot()) return image
}</lang>Note: As of this writing the grayscale image task has not been implemented, so the task code (below) won't actually run yet. But readPPM above has been tested separately.
<lang e>def readPPMTask(inputFile, outputFile) {
makeGrayscale \ .fromColor(readPPM(<import:java.io.makeFileInputStream>(inputFile))) \ .toColor() \ .writePPM(<import:java.io.makeFileOutputStream>(outputFile))
}</lang>
Erlang
<lang erlang> % This module provides basic operations on ppm files: % Read from file, create ppm in memory (from generic bitmap) and save to file. % Writing PPM files was introduced in roseta code task 'Bitmap/Write a PPM file' % but the same code is included here to provide whole set of operations on ppm % needed for purposes of this task.
-module(ppm).
-export([ppm/1, write/2, read/1]).
% constants for writing ppm file -define(WHITESPACE, <<10>>). -define(SPACE, <<32>>).
% constants for reading ppm file -define(WHITESPACES, [9, 10, 13, 32]). -define(PPM_HEADER, "P6").
% data structure introduced in task Bitmap (module ros_bitmap.erl) -record(bitmap, {
mode = rgb,
pixels = nil,
shape = {0, 0}
}).
%%%%%%%%% API %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% read ppm file from file read(Filename) ->
{ok, File} = file:read_file(Filename),
parse(File).
% create ppm image from bitmap record ppm(Bitmap) ->
{Width, Height} = Bitmap#bitmap.shape,
Pixels = ppm_pixels(Bitmap),
Maxval = 255, % original ppm format maximum
list_to_binary([
header(), width_and_height(Width, Height), maxval(Maxval), Pixels]).
% write bitmap as ppm file write(Bitmap, Filename) ->
Ppm = ppm(Bitmap),
{ok, File} = file:open(Filename, [binary, write]),
file:write(File, Ppm),
file:close(File).
%%%%%%%%% Reading PPM %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% parse(Binary) ->
{?PPM_HEADER, Data} = get_next_token(Binary),
{Width, HeightAndRest} = get_next_token(Data),
{Height, MaxValAndRest} = get_next_token(HeightAndRest),
{_MaxVal, RawPixels} = get_next_token(MaxValAndRest),
Shape = {list_to_integer(Width), list_to_integer(Height)},
Pixels = load_pixels(RawPixels),
#bitmap{pixels=Pixels, shape=Shape}.
% load binary as a list of RGB triplets load_pixels(Binary) when is_binary(Binary)->
load_pixels([], Binary).
load_pixels(Acc, <<>>) ->
array:from_list(lists:reverse(Acc));
load_pixels(Acc, <<R, G, B, Rest/binary>>) ->
load_pixels([<<R,G,B>>|Acc], Rest).
is_whitespace(Byte) ->
lists:member(Byte, ?WHITESPACES).
% get next part of PPM file, skip whitespaces, and return the rest of a binary get_next_token(Binary) ->
get_next_token("", true, Binary).
get_next_token(CurrentToken, false, <<Byte, Rest/binary>>) ->
case is_whitespace(Byte) of
true ->
{lists:reverse(CurrentToken), Rest};
false ->
get_next_token([Byte | CurrentToken], false, Rest)
end;
get_next_token(CurrentToken, true, <<Byte, Rest/binary>>) ->
case is_whitespace(Byte) of
true ->
get_next_token(CurrentToken, true, Rest);
false ->
get_next_token([Byte | CurrentToken], false, Rest)
end.
%%%%%%%%% Writing PPM %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% header() ->
[<<"P6">>, ?WHITESPACE].
width_and_height(Width, Height) ->
[encode_decimal(Width), ?SPACE, encode_decimal(Height), ?WHITESPACE].
maxval(Maxval) ->
[encode_decimal(Maxval), ?WHITESPACE].
ppm_pixels(Bitmap) ->
% 24 bit color depth array:to_list(Bitmap#bitmap.pixels).
encode_decimal(Number) ->
integer_to_list(Number).
</lang>
Usage in accordance with Grayscale Task: <lang erlang> Colorful = ppm:read("colorful.ppm"), Gray = ros_bitmap:convert(ros_bitmap:convert(Colorful, grey), rgb), ppm:write(Gray, "gray.ppm"), </lang>
Euphoria
<lang euphoria>include get.e
function get2(integer fn)
sequence temp temp = get(fn) return temp[2] - temp[1]*temp[1]
end function
function read_ppm(sequence filename)
sequence image, line
integer dimx, dimy, maxcolor
atom fn
fn = open(filename, "rb")
if fn < 0 then
return -1 -- unable to open
end if
line = gets(fn)
if not equal(line,"P6\n") then
return -1 -- only ppm6 files are supported
end if
dimx = get2(fn)
if dimx < 0 then
return -1
end if
dimy = get2(fn)
if dimy < 0 then
return -1
end if
maxcolor = get2(fn)
if maxcolor != 255 then
return -1 -- maxcolors other then 255 are not supported
end if
image = repeat(repeat(0,dimy),dimx)
for y = 1 to dimy do
for x = 1 to dimx do
image[x][y] = getc(fn)*#10000 + getc(fn)*#100 + getc(fn)
end for
end for
close(fn)
return image
end function</lang>
Converting an image to grayscale: <lang euphoria>sequence image image = read_ppm("image.ppm") image = to_gray(image) image = to_color(image) write_ppm("image_gray.ppm",image)</lang>
FBSL
Read a colored PPM file, convert it to grayscale and write back to disk under a different name. Sanity checks are omitted for brevity.
24-bpp P6 PPM solution:
<lang qbasic>#ESCAPECHARS ON
DIM colored = ".\\Lena.ppm", grayscale = ".\\LenaGry.ppm" DIM head, tail, r, g, b, l, ptr, blobsize
FILEGET(FILEOPEN(colored, BINARY), FILELEN(colored)): FILECLOSE(FILEOPEN) ' Load buffer blobsize = INSTR(FILEGET, "\n255\n") + 4 ' Get sizeof PPM header head = @FILEGET + blobsize: tail = @FILEGET + FILELEN ' Set loop bounds
FOR ptr = head TO tail STEP 3 ' Transform color triplets r = PEEK(ptr + 0, 1) ' Read colors stored in RGB order g = PEEK(ptr + 1, 1) b = PEEK(ptr + 2, 1) l = 0.2126 * r + 0.7152 * g + 0.0722 * b ' Derive luminance POKE(ptr + 0, CHR(l))(ptr + 1, CHR)(ptr + 2, CHR) ' Write grayscale NEXT
FILEPUT(FILEOPEN(grayscale, BINARY_NEW), FILEGET): FILECLOSE(FILEOPEN) ' Save buffer</lang>
Forth
<lang forth>: read-ppm { fid -- bmp }
pad dup 80 fid read-line throw 0= abort" Partial line"
s" P6" compare abort" Only P6 supported."
pad dup 80 fid read-line throw 0= abort" Partial line"
0. 2swap >number
1 /string \ skip space
0. 2swap >number
2drop drop nip ( w h )
bitmap { bmp }
pad dup 80 fid read-line throw 0= abort" Partial line"
s" 255" compare abort" Only 8-bits per color channel supported"
0 pad !
bmp bdim
0 do
dup 0 do
pad 3 fid read-file throw
3 - abort" Not enough pixel data in file"
pad @ i j bmp b!
loop
loop drop
bmp ;
\ testing round-trip 4 3 bitmap value test red test bfill green 1 2 test b!
s" red.ppm" w/o create-file throw test over write-ppm close-file throw
s" red.ppm" r/o open-file throw dup read-ppm value test2 close-file throw
- bsize ( bmp -- len ) bdim * pixels bdata ;
test dup bsize test2 dup bsize compare . \ 0 if identical</lang>
Fortran
(This function is part of module RCImageIO, see Write ppm file)
<lang fortran>subroutine read_ppm(u, img)
integer, intent(in) :: u type(rgbimage), intent(out) :: img integer :: i, j, ncol, cc character(2) :: sign character :: ccode img%width = 0 img%height = 0 nullify(img%red) nullify(img%green) nullify(img%blue)
read(u, '(A2)') sign read(u, *) img%width, img%height read(u, *) ncol
write(0,*) sign write(0,*) img%width, img%height write(0,*) ncol
if ( ncol /= 255 ) return
call alloc_img(img, img%width, img%height)
if ( valid_image(img) ) then
do j=1, img%height
do i=1, img%width
read(u, '(A1)', advance='no', iostat=status) ccode
cc = iachar(ccode)
img%red(i,j) = cc
read(u, '(A1)', advance='no', iostat=status) ccode
cc = iachar(ccode)
img%green(i,j) = cc
read(u, '(A1)', advance='no', iostat=status) ccode
cc = iachar(ccode)
img%blue(i,j) = cc
end do
end do
end if
end subroutine read_ppm</lang>
Notes:
- doing formatted I/O with Fortran is a pain... And unformatted does not mean free; Fortran2003 has streams, but they are not implemented (yet) in GNU Fortran compiler. Here (as in the write part) I've tried to handle the PPM format through formatted I/O. The tests worked but I have not tried still everything.
- comments after the first line are not handled
Go
<lang go>package raster
import (
"errors" "io" "io/ioutil" "os" "regexp" "strconv"
)
// ReadFrom constructs a Bitmap object from an io.Reader. func ReadPpmFrom(r io.Reader) (b *Bitmap, err error) {
var all []byte
all, err = ioutil.ReadAll(r)
if err != nil {
return
}
bss := rxHeader.FindSubmatch(all)
if bss == nil {
return nil, errors.New("unrecognized ppm header")
}
x, _ := strconv.Atoi(string(bss[3]))
y, _ := strconv.Atoi(string(bss[6]))
maxval, _ := strconv.Atoi(string(bss[9]))
if maxval > 255 {
return nil, errors.New("16 bit ppm not supported")
}
allCmts := append(append(append(bss[1], bss[4]...), bss[7]...), bss[10]...)
b = NewBitmap(x, y)
b.Comments = rxComment.FindAllString(string(allCmts), -1)
b3 := all[len(bss[0]):]
var n1 int
for i := range b.px {
b.px[i].R = byte(int(b3[n1]) * 255 / maxval)
b.px[i].G = byte(int(b3[n1+1]) * 255 / maxval)
b.px[i].B = byte(int(b3[n1+2]) * 255 / maxval)
n1 += 3
}
return
}
const (
// single whitespace character
ws = "[ \n\r\t\v\f]"
// isolated comment
cmt = "#[^\n\r]*"
// comment sub expression
cmts = "(" + ws + "*" + cmt + "[\n\r])"
// number with leading comments
num = "(" + cmts + "+" + ws + "*|" + ws + "+)([0-9]+)"
)
var rxHeader = regexp.MustCompile("^P6" + num + num + num +
"(" + cmts + "*" + ")" + ws)
var rxComment = regexp.MustCompile(cmt)
// ReadFile writes binary P6 format PPM from the specified filename. func ReadPpmFile(fn string) (b *Bitmap, err error) {
var f *os.File
if f, err = os.Open(fn); err != nil {
return
}
if b, err = ReadPpmFrom(f); err != nil {
return
}
return b, f.Close()
}</lang> Demonstration program, also demonstrating functions from task Grayscale image: <lang go>package main
// Files required to build supporting package raster are found in: // * This task (immediately above) // * Bitmap // * Grayscale image // * Write a PPM file
import (
"raster" "fmt"
)
func main() {
// (A file with this name is output by the Go solution to the task
// "Bitmap/Read an image through a pipe," but of course any 8-bit
// P6 PPM file should work.)
b, err := raster.ReadPpmFile("pipein.ppm")
if err != nil {
fmt.Println(err)
return
}
b = b.Grmap().Bitmap()
err = b.WritePpmFile("grayscale.ppm")
if err != nil {
fmt.Println(err)
}
}</lang>
Haskell
The definition of Bitmap.Netpbm.readNetpbm is given here. <lang haskell>import Bitmap import Bitmap.RGB import Bitmap.Gray import Bitmap.Netpbm
import Control.Monad import Control.Monad.ST
main =
(readNetpbm "original.ppm" :: IO (Image RealWorld RGB)) >>= stToIO . toGrayImage >>= writeNetpbm "new.pgm"</lang>
The above writes a PGM, not a PPM, since the image being output is in grayscale. If you actually want a gray PPM, convert the Image RealWorld Gray back to an Image RealWorld RGB first: <lang haskell>main =
(readNetpbm "original.ppm" :: IO (Image RealWorld RGB)) >>= stToIO . (toRGBImage <=< toGrayImage) >>= writeNetpbm "new.ppm"</lang>
J
Solution:
Uses makeRGB from Basic bitmap storage.
<lang j>require 'files'
readppm=: monad define
dat=. fread y NB. read from file
msk=. 1 ,~ (*. 3 >: +/\) (LF&=@}: *. '#'&~:@}.) dat NB. mark field ends
't wbyh maxval dat'=. msk <;._2 dat NB. parse
'wbyh maxval'=. 2 1([ {. [: _99&". (LF,' ')&charsub)&.> wbyh;maxval NB. convert to numeric
if. (_99 0 +./@e. wbyh,maxval) +. 'P6' -.@-: 2{.t do. _1 return. end.
(a. i. dat) makeRGB |.wbyh NB. convert to basic bitmap format
)</lang>
Example:
Using utilities and file from Grayscale image and Write ppm file.
Writes a gray PPM file (a color format) which is bigger than necessary. A PGM file would be more appropriate.
<lang j>myimg=: readppm jpath '~temp/myimg.ppm'
myimgGray=: toColor toGray myimg
myimgGray writeppm jpath '~temp/myimgGray.ppm'</lang>
Julia
<lang julia>using Images, FileIO, Netpbm
rgbimg = load("data/bitmapInputTest.ppm") greyimg = Gray.(rgbimg) save("data/bitmapOutputTest.ppm", greyimg)</lang>
Kotlin
For convenience, we repeat the code for the class used in the Bitmap task here and integrate the code in the Grayscale image task within it. <lang scala>// Version 1.2.40
import java.awt.Color import java.awt.Graphics import java.awt.image.BufferedImage import java.io.FileInputStream import java.io.PushbackInputStream import java.io.File import javax.imageio.ImageIO
class BasicBitmapStorage(width: Int, height: Int) {
val image = BufferedImage(width, height, BufferedImage.TYPE_3BYTE_BGR)
fun fill(c: Color) {
val g = image.graphics
g.color = c
g.fillRect(0, 0, image.width, image.height)
}
fun setPixel(x: Int, y: Int, c: Color) = image.setRGB(x, y, c.getRGB())
fun getPixel(x: Int, y: Int) = Color(image.getRGB(x, y))
fun toGrayScale() {
for (x in 0 until image.width) {
for (y in 0 until image.height) {
var rgb = image.getRGB(x, y)
val red = (rgb shr 16) and 0xFF
val green = (rgb shr 8) and 0xFF
val blue = rgb and 0xFF
val lumin = (0.2126 * red + 0.7152 * green + 0.0722 * blue).toInt()
rgb = (lumin shl 16) or (lumin shl 8) or lumin
image.setRGB(x, y, rgb)
}
}
}
}
fun PushbackInputStream.skipComment() {
while (read().toChar() != '\n') {}
}
fun PushbackInputStream.skipComment(buffer: ByteArray) {
var nl: Int
while (true) {
nl = buffer.indexOf(10) // look for newline at end of comment
if (nl != -1) break
read(buffer) // read another buffer full if newline not yet found
}
val len = buffer.size
if (nl < len - 1) unread(buffer, nl + 1, len - nl - 1)
}
fun Byte.toUInt() = if (this < 0) 256 + this else this.toInt()
fun main(args: Array<String>) {
// use file, output.ppm, created in the Bitmap/Write a PPM file task
val pbis = PushbackInputStream(FileInputStream("output.ppm"), 80)
pbis.use {
with (it) {
val h1 = read().toChar()
val h2 = read().toChar()
val h3 = read().toChar()
if (h1 != 'P' || h2 != '6' || h3 != '\n') {
println("Not a P6 PPM file")
System.exit(1)
}
val sb = StringBuilder()
while (true) {
val r = read().toChar()
if (r == '#') { skipComment(); continue }
if (r == ' ') break // read until space reached
sb.append(r.toChar())
}
val width = sb.toString().toInt()
sb.setLength(0)
while (true) {
val r = read().toChar()
if (r == '#') { skipComment(); continue }
if (r == '\n') break // read until new line reached
sb.append(r.toChar())
}
val height = sb.toString().toInt()
sb.setLength(0)
while (true) {
val r = read().toChar()
if (r == '#') { skipComment(); continue }
if (r == '\n') break // read until new line reached
sb.append(r.toChar())
}
val maxCol = sb.toString().toInt()
if (maxCol !in 0..255) {
println("Maximum color value is outside the range 0..255")
System.exit(1)
}
var buffer = ByteArray(80)
// get rid of any more opening comments before reading data
while (true) {
read(buffer)
if (buffer[0].toChar() == '#') {
skipComment(buffer)
}
else {
unread(buffer)
break
}
}
// read data
val bbs = BasicBitmapStorage(width, height)
buffer = ByteArray(width * 3)
var y = 0
while (y < height) {
read(buffer)
for (x in 0 until width) {
val c = Color(
buffer[x * 3].toUInt(),
buffer[x * 3 + 1].toUInt(),
buffer[x * 3 + 2].toUInt()
)
bbs.setPixel(x, y, c)
}
y++
}
// convert to grayscale and save to a file
bbs.toGrayScale()
val grayFile = File("output_gray.jpg")
ImageIO.write(bbs.image, "jpg", grayFile)
}
}
}</lang>
Lua
<lang lua>function Read_PPM( filename )
local fp = io.open( filename, "rb" ) if fp == nil then return nil end
local data = fp:read( "*line" )
if data ~= "P6" then return nil end
repeat
data = fp:read( "*line" )
until string.find( data, "#" ) == nil
local image = {}
local size_x, size_y
size_x = string.match( data, "%d+" )
size_y = string.match( data, "%s%d+" )
data = fp:read( "*line" ) if tonumber(data) ~= 255 then return nil end
for i = 1, size_x do
image[i] = {}
end
for j = 1, size_y do
for i = 1, size_x do
image[i][j] = { string.byte( fp:read(1) ), string.byte( fp:read(1) ), string.byte( fp:read(1) ) }
end
end
fp:close()
return image
end</lang>
M2000 Interpreter
Now function Bitmap has double signature. With two numbers make a bitmap,with all pixels white. With one number, expect that it is a file number and read file, and then return the bitmap.
<lang M2000 Interpreter> Module Checkit {
Function Bitmap {
If match("NN") then {
Read x as long, y as long
} else.if Match("N") Then {
\\ is a file?
Read f
if not Eof(f) then {
Line Input #f, p3$
If p3$="P3" Then {
Line Input #f, Comment$
if left$(Comment$,1)="#" then {
Line Input #f, Dimension$
} else Dimension$=Comment$
long x=Val(piece$(Dimension$," ")(0))
long y=Val(piece$(Dimension$," ")(1))
do {
Line Input #f, P255$
} until left$(P255$, 1)<>"#"
If not P255$="255" then Error "Not proper ppm format"
}
}
} else Error "No proper arguments"
if x<1 or y<1 then Error "Wrong dimensions"
structure rgb {
red as byte
green as byte
blue as byte
}
m=len(rgb)*x mod 4
if m>0 then m=4-m ' add some bytes to raster line
m+=len(rgb) *x
Structure rasterline {
{
pad as byte*m
}
\\ union pad+hline
hline as rgb*x
}
Structure Raster {
magic as integer*4
w as integer*4
h as integer*4
lines as rasterline*y
}
Buffer Clear Image1 as Raster
\\ 24 chars as header to be used from bitmap render build in functions
Return Image1, 0!magic:="cDIB", 0!w:=Hex$(x,2), 0!h:=Hex$(y, 2)
\\ fill white (all 255)
\\ Str$(string) convert to ascii, so we get all characters from words width to byte width
if not valid(f) then Return Image1, 0!lines:=Str$(String$(chrcode$(255), Len(rasterline)*y))
Buffer Clear Pad as Byte*4
SetPixel=Lambda Image1, Pad,aLines=Len(Raster)-Len(Rasterline), blines=-Len(Rasterline) (x, y, c) ->{
where=alines+3*x+blines*y
if c>0 then c=color(c)
c-!
Return Pad, 0:=c as long
Return Image1, 0!where:=Eval(Pad, 2) as byte, 0!where+1:=Eval(Pad, 1) as byte, 0!where+2:=Eval(Pad, 0) as byte
}
GetPixel=Lambda Image1,aLines=Len(Raster)-Len(Rasterline), blines=-Len(Rasterline) (x,y) ->{
where=alines+3*x+blines*y
=color(Eval(image1, where+2 as byte), Eval(image1, where+1 as byte), Eval(image1, where as byte))
}
StrDib$=Lambda$ Image1, Raster -> {
=Eval$(Image1, 0, Len(Raster))
}
CopyImage=Lambda Image1 (image$) -> {
if left$(image$,12)=Eval$(Image1, 0, 24 ) Then {
Return Image1, 0:=Image$
} Else Error "Can't Copy Image"
}
Export2File=Lambda Image1, x, y (f) -> {
\\ use this between open and close
Print #f, "P3"
Print #f,"# Created using M2000 Interpreter"
Print #f, x;" ";y
Print #f, 255
x2=x-1
where=24
For y1= 0 to y-1 {
a$=""
For x1=0 to x2 {
Print #f, a$;Eval(Image1, where+2 as byte);" ";
Print #f, Eval(Image1, where+1 as byte);" ";
Print #f, Eval(Image1, where as byte);
where+=3
a$=" "
}
Print #f
m=where mod 4
if m<>0 then where+=4-m
}
}
if valid(F) then {
'load RGB values form file
x0=x-1
where=24
For y1=y-1 to 0 {
do {
Line Input #f, aline$
} until left$(aline$,1)<>"#"
flush ' empty stack
Stack aline$ ' place all values to stack as FIFO
For x1=0 to x0 {
\\ now read from stack using Number
Return Image1, 0!where+2:=Number as byte, 0!where+1:=Number as byte, 0!where:=Number as byte
where+=3
}
m=where mod 4
if m<>0 then where+=4-m
}
}
Group Bitmap {
SetPixel=SetPixel
GetPixel=GetPixel
Image$=StrDib$
Copy=CopyImage
ToFile=Export2File
}
=Bitmap
}
A=Bitmap(10, 10)
Call A.SetPixel(5,5, color(128,0,255))
Open "A.PPM" for Output as #F
Call A.ToFile(F)
Close #f
Open "A.PPM" for Input as #F
Try {
C=Bitmap(f)
Copy 400*twipsx,200*twipsy use C.Image$()
}
Close #f
' is the same as this one
Open "A.PPM" for Input as #F
Line Input #f, p3$
If p3$="P3" Then {
Line Input #f, Comment$
if left$(Comment$,1)="#" then {
Line Input #f, Dimension$
} else Dimension$=Comment$
Long x=Val(piece$(Dimension$," ")(0))
Long y=Val(piece$(Dimension$," ")(1))
do {
Line Input #f, P255$
} until left$(P255$, 1)<>"#"
If not P255$="255" then Error "Not proper ppm format"
B=Bitmap(x, y)
x0=x-1
For y1=y-1 to 0 {
do {
Line Input #f, aline$
} until left$(aline$,1)<>"#"
flush ' empty stack
Stack aline$ ' place all values to stack as FIFO
For x1=0 to x0 {
\\ now read from stack
Read red, green, blue
Call B.setpixel(x1, y1, Color(red, green, blue))
}
}
}
Close #f
If valid("B") then Copy 200*twipsx,200*twipsy use B.Image$()
} Checkit
</lang>
Mathematica/ Wolfram Language
<lang Mathematica>Import["file.ppm","PPM"] </lang>
Nim
<lang nim>import strutils import bitmap
type FormatError = object of CatchableError
- States used to parse the header.
type State = enum waitingMagic, waitingWidth, waitingHeight, waitingColors
- ---------------------------------------------------------------------------------------------------
iterator tokens(f: File): tuple[value: string, lastInLine: bool] =
## Yield the tokens in the header.
for line in f.lines:
if not line.startsWith('#'):
let fields = line.splitWhitespace()
for i, t in fields:
yield (t, i == fields.high)
- ---------------------------------------------------------------------------------------------------
proc getInt(s: string): int {.inline.} =
## Try to parse an int. Raise an exception if not an integer. try: result = s.parseInt() except ValueError: raise newException(FormatError, "Invalid value")
- ---------------------------------------------------------------------------------------------------
proc header(f: File): tuple[width, height: Index] =
## Read the header and return the image width and height.
var state = waitingMagic
for (token, lastInLine) in f.tokens:
case state
of waitingMagic:
if token != "P6":
raise newException(FormatError, "Invalid file header")
of waitingWidth:
result.width = token.getInt()
of waitingHeight:
result.height = token.getInt()
of waitingColors:
if token.getInt() != 255:
raise newException(FormatError, "Invalid number of colors")
if not lastInLine:
raise newException(FormatError, "Invalid data after number of colors")
break
state = succ(state)
- ---------------------------------------------------------------------------------------------------
proc readPPM(f: File): Image =
## Read a PPM file into an image.
let header = f.header() result = initImage(header.width, header.height)
var arr: array[256, int8] read = f.readBytes(arr, 0, 256) pos = 0
while read != 0:
for i in 0 ..< read:
case pos mod 3
of 0: result.pixels[pos div 3].r = arr[i].uint8
of 1: result.pixels[pos div 3].g = arr[i].uint8
of 2: result.pixels[pos div 3].b = arr[i].uint8
else: discard
inc pos
read = f.readBytes(arr, 0, 256)
if pos != 3 * result.w * result.h: raise newException(FormatError, "Truncated file")
- ---------------------------------------------------------------------------------------------------
proc readPPM*(filename: string): Image =
## Load a PPM file into an image.
var file = open(filename, fmRead) result = file.readPPM() file.close()</lang>
OCaml
<lang ocaml>let read_ppm ~filename =
let ic = open_in filename in
let line = input_line ic in
if line <> "P6" then invalid_arg "not a P6 ppm file";
let line = input_line ic in
let line =
try if line.[0] = '#' (* skip comments *)
then input_line ic
else line
with _ -> line
in
let width, height =
Scanf.sscanf line "%d %d" (fun w h -> (w, h))
in
let line = input_line ic in
if line <> "255" then invalid_arg "not a 8 bit depth image";
let all_channels =
let kind = Bigarray.int8_unsigned
and layout = Bigarray.c_layout
in
Bigarray.Array3.create kind layout 3 width height
in
let r_channel = Bigarray.Array3.slice_left_2 all_channels 0
and g_channel = Bigarray.Array3.slice_left_2 all_channels 1
and b_channel = Bigarray.Array3.slice_left_2 all_channels 2
in
for y = 0 to pred height do
for x = 0 to pred width do
r_channel.{x,y} <- (input_byte ic);
g_channel.{x,y} <- (input_byte ic);
b_channel.{x,y} <- (input_byte ic);
done;
done;
close_in ic;
(all_channels,
r_channel,
g_channel,
b_channel)</lang>
and converting a given color file to grayscale: <lang ocaml>let () =
let img = read_ppm ~filename:"logo.ppm" in let img = to_color(to_grayscale ~img) in output_ppm ~oc:stdout ~img;
- </lang>
sending the result to stdout allows to see the result without creating a temporary file sending it through a pipe to the display utility of ImageMagick:
ocaml script.ml | display -
Oz
The read function in module "BitmapIO.oz":
<lang oz>functor
import
Bitmap Open
export
Read %% Write
define
fun {Read Filename}
F = {New Open.file init(name:Filename)}
fun {ReadColor8 _}
Bytes = {F read(list:$ size:3)}
in
{List.toTuple color Bytes}
end
fun {ReadColor16 _}
Bytes = {F read(list:$ size:6)}
in
{List.toTuple color {Map {PairUp Bytes} FromBytes}}
end
in
try
Magic = {F read(size:2 list:$)} if Magic \= "P6" then raise bitmapIO(read unsupportedFormat(Magic)) end end Width = {ReadNumber F} Height = {ReadNumber F} MaxVal = {ReadNumber F} MaxVal =< 0xffff = true Reader = if MaxVal =< 0xff then ReadColor8 else ReadColor16 end B = {Bitmap.new Width Height}
in
{Bitmap.transform B Reader} B
finally
{F close}
end end
fun {ReadNumber F}
Ds
in
{SkipWS F}
Ds = for collect:Collect break:Break do
[C] = {F read(list:$ size:1)} in if {Char.isDigit C} then {Collect C} else {Break} end end
{SkipWS F}
{String.toInt Ds}
end
proc {SkipWS F}
[C] = {F read(list:$ size:1)}
in
if {Char.isSpace C} then {SkipWS F}
elseif C == &# then
{SkipLine F}
else
{F seek(whence:current offset:~1)}
end end
proc {SkipLine F}
[C] = {F read(list:$ size:1)}
in
if C \= &\n andthen C \= &\r then {SkipLine F} end
end
fun {PairUp Xs}
case Xs of X1|X2|Xr then [X1 X2]|{PairUp Xr}
[] nil then nil
end
end
fun {FromBytes [C1 C2]}
C1 * 0x100 + C2
end
%% Omitted: Write
end</lang>
The actual task: <lang oz>declare
[BitmapIO Grayscale] = {Module.link ['BitmapIO.ozf' 'Grayscale.ozf']}
B = {BitmapIO.read "image.ppm"}
G = {Grayscale.toGraymap B}
in
{BitmapIO.write {Grayscale.fromGraymap G} "greyimage.ppm"}</lang>
Perl
<lang perl>#! /usr/bin/perl
use strict; use Image::Imlib2;
my $img = Image::Imlib2->load("out0.ppm");
- let's do something with it now
$img->set_color(255, 255, 255, 255); $img->draw_line(0,0, $img->width,$img->height); $img->image_set_format("png"); $img->save("out1.png");
exit 0;</lang>
Phix
Based on Euphoria, requires write_ppm() from Write_a_PPM_file, to_gray from Grayscale_image <lang Phix>function read_ppm(sequence filename) sequence image, line integer dimx, dimy, maxcolor atom fn = open(filename, "rb")
if fn<0 then
return -1 -- unable to open
end if
line = gets(fn)
if line!="P6\n" then
return -1 -- only ppm6 files are supported
end if
line = gets(fn)
Template:Dimx,dimy = scanf(line,"%d %d%s")
line = gets(fn)
Template:Maxcolor = scanf(line,"%d%s")
image = repeat(repeat(0,dimy),dimx)
for y=1 to dimy do
for x=1 to dimx do
image[x][y] = getc(fn)*#10000 + getc(fn)*#100 + getc(fn)
end for
end for
close(fn)
return image
end function
sequence img = read_ppm("Lena.ppm")
img = to_gray(img)
write_ppm("LenaGray.ppm",img)</lang>
PicoLisp
<lang PicoLisp>(de ppmRead (File)
(in File
(unless (and `(hex "5036") (rd 2)) # P6
(quit "Wrong file format" File) )
(rd 1)
(let (DX 0 DY 0 Max 0 C)
(while (>= 9 (setq C (- (rd 1) `(char "0"))) 0)
(setq DX (+ (* 10 DX) C)) )
(while (>= 9 (setq C (- (rd 1) `(char "0"))) 0)
(setq DY (+ (* 10 DY) C)) )
(while (>= 9 (setq C (- (rd 1) `(char "0"))) 0)
(setq Max (+ (* 10 Max) C)) )
(prog1
(make (do DY (link (need DX))))
(for Y @
(map
'((X) (set X (list (rd 1) (rd 1) (rd 1))))
Y ) ) ) ) ) )</lang>
Read a color image "img.ppm", convert and write to "img.pgm": <lang PicoLisp>(pgmWrite (ppm->pgm (ppmRead "img.ppm")) "img.pgm")</lang>
PL/I
<lang PL/I> /* BITMAP FILE: read in a file in PPM format, P6 (binary). 14/5/2010 */ test: procedure options (main);
declare (m, n, max_color, i, j) fixed binary (31);
declare ch character (1), ID character (2);
declare 1 pixel union,
2 color bit(24) aligned,
2 primary_colors,
3 R char (1),
3 G char (1),
3 B char (1);
declare in file record;
open file (in) title ('/IMAGE.PPM,TYPE(FIXED),RECSIZE(1)' ) input;
call get_char; ID = ch; call get_char; substr(ID, 2,1) = ch; /* Read in the dimensions of the image */ call get_integer (m); call get_integer (n);
/* Read in the maximum color size used */
call get_integer (max_color);
/* The previous call reads in ONE line feed or CR or other terminator */
/* character. */
begin;
declare image (0:m-1,0:n-1) bit (24);
do i = 0 to hbound(image, 1);
do j = 0 to hbound(image,2);
read file (in) into (R);
read file (in) into (G);
read file (in) into (B);
image(i,j) = color;
end;
end;
end;
get_char: procedure;
do until (ch ^= ' ');
read file (in) into (ch);
end;
end get_char;
get_integer: procedure (value);
declare value fixed binary (31);
do until (ch = ' ');
read file (in) into (ch);
end;
value = 0;
do until (is_digit(ch));
value = value*10 + ch;
read file (in) into (ch);
end;
end get_integer;
is_digit: procedure (ch) returns (bit(1));
declare ch character (1);
return (index('0123456789', ch) > 0);
end is_digit; end test;</lang>
PureBasic
<lang PureBasic>Structure PPMColor
r.c g.c b.c
EndStructure
Procedure LoadImagePPM(Image, file$)
; Author Roger Rösch (Nickname Macros)
IDFile = ReadFile(#PB_Any, file$)
If IDFile
If CreateImage(Image, 1, 1)
Format$ = ReadString(IDFile)
ReadString(IDFile) ; skip comment
Dimensions$ = ReadString(IDFile)
w = Val(StringField(Dimensions$, 1, " "))
h = Val(StringField(Dimensions$, 2, " "))
ResizeImage(Image, w, h)
StartDrawing(ImageOutput(Image))
max = Val(ReadString(IDFile)) ; Maximal Value for a color
Select Format$
Case "P3" ; File in ASCII format
; Exract everey number remaining in th file into an array using an RegEx
Stringlen = Lof(IDFile) - Loc(IDFile)
content$ = Space(Stringlen)
Dim color.s(0)
ReadData(IDFile, @content$, Stringlen)
CreateRegularExpression(1, "\d+")
ExtractRegularExpression(1, content$, color())
; Plot color information on our empty Image
For y = 0 To h - 1
For x = 0 To w - 1
pos = (y*w + x)*3
r=Val(color(pos))*255 / max
g=Val(color(pos+1))*255 / max
b=Val(color(pos+2))*255 / max
Plot(x, y, RGB(r,g,b))
Next
Next
Case "P6" ;File In binary format
; Read whole bytes into a buffer because its faster than reading single ones
Bufferlen = Lof(IDFile) - Loc(IDFile)
*Buffer = AllocateMemory(Bufferlen)
ReadData(IDFile, *Buffer, Bufferlen)
; Plot color information on our empty Image
For y = 0 To h - 1
For x = 0 To w - 1
*color.PPMColor = pos + *Buffer
Plot(x, y, RGB(*color\r*255 / max, *color\g*255 / max, *color\b*255 / max))
pos + 3
Next
Next
EndSelect
StopDrawing()
; Return 1 if successfully loaded to behave as other PureBasic functions
ProcedureReturn 1
EndIf
EndIf
EndProcedure</lang>
To complete the task, the following code should be added to the above fragment and to the PureBasic solutions for Grayscale image and Write a PPM file <lang PureBasic>Define file.s, file2.s, image = 3 file = OpenFileRequester("Select source image file", "", "PPM image (*.ppm)|*.ppm", 0) If file And LCase(GetExtensionPart(file)) = "ppm"
LoadImagePPM(image, file) ImageGrayout(image) file2 = Left(file, Len(file) - Len(GetExtensionPart(file))) + "_grayscale." + GetExtensionPart(file) SaveImageAsPPM(image, file2, 1)
EndIf</lang>
Python
Extending the example given here <lang python># With help from http://netpbm.sourceforge.net/doc/ppm.html
- String masquerading as ppm file (version P3)
import io
ppmtxt = P3
- feep.ppm
4 4 15
0 0 0 0 0 0 0 0 0 15 0 15 0 0 0 0 15 7 0 0 0 0 0 0 0 0 0 0 0 0 0 15 7 0 0 0
15 0 15 0 0 0 0 0 0 0 0 0
def tokenize(f):
for line in f:
if line[0] != '#':
for t in line.split():
yield t
def ppmp3tobitmap(f):
t = tokenize(f)
nexttoken = lambda : next(t)
assert 'P3' == nexttoken(), 'Wrong filetype'
width, height, maxval = (int(nexttoken()) for i in range(3))
bitmap = Bitmap(width, height, Colour(0, 0, 0))
for h in range(height-1, -1, -1):
for w in range(0, width):
bitmap.set(w, h, Colour( *(int(nexttoken()) for i in range(3))))
return bitmap
print('Original Colour PPM file') print(ppmtxt) ppmfile = io.StringIO(ppmtxt) bitmap = ppmp3tobitmap(ppmfile) print('Grey PPM:') bitmap.togreyscale() ppmfileout = io.StringIO() bitmap.writeppmp3(ppmfileout) print(ppmfileout.getvalue())
The print statements above produce the following output:
Original Colour PPM file P3
- feep.ppm
4 4 15
0 0 0 0 0 0 0 0 0 15 0 15 0 0 0 0 15 7 0 0 0 0 0 0 0 0 0 0 0 0 0 15 7 0 0 0
15 0 15 0 0 0 0 0 0 0 0 0
Grey PPM: P3
- generated from Bitmap.writeppmp3
4 4 11
0 0 0 0 0 0 0 0 0 4 4 4 0 0 0 11 11 11 0 0 0 0 0 0 0 0 0 0 0 0 11 11 11 0 0 0 4 4 4 0 0 0 0 0 0 0 0 0
</lang>
Racket
<lang racket>
- lang racket
(require racket/draw)
(define (read-ppm port)
(parameterize ([current-input-port port])
(define magic (read))
(define width (read))
(define height (read))
(define maxcol (read))
(define bm (make-object bitmap% width height))
(define dc (new bitmap-dc% [bitmap bm]))
(send dc set-smoothing 'unsmoothed)
(define (adjust v) (* 255 (/ v maxcol)))
(for/list ([x width])
(for/list ([y height])
(define red (read))
(define green (read))
(define blue (read))
(define color (make-object color% (adjust red) (adjust green) (adjust blue)))
(send dc set-pen color 1 'solid)
(send dc draw-point x y)))
bm))
</lang>
Raku
(formerly Perl 6)
Uses pieces from Bitmap, Write a PPM file and Grayscale image tasks. Included here to make a complete, runnable program.
<lang perl6>class Pixel { has UInt ($.R, $.G, $.B) } class Bitmap {
has UInt ($.width, $.height); has Pixel @.data;
}
role PGM {
has @.GS;
method P5 returns Blob {
"P5\n{self.width} {self.height}\n255\n".encode('ascii') ~ Blob.new: self.GS
}
}
sub load-ppm ( $ppm ) {
my $fh = $ppm.IO.open( :enc('ISO-8859-1') );
my $type = $fh.get;
my ($width, $height) = $fh.get.split: ' ';
my $depth = $fh.get;
Bitmap.new( width => $width.Int, height => $height.Int,
data => ( $fh.slurp.ords.rotor(3).map:
{ Pixel.new(R => $_[0], G => $_[1], B => $_[2]) } )
)
}
sub grayscale ( Bitmap $bmp ) {
$bmp.GS = map { (.R*0.2126 + .G*0.7152 + .B*0.0722).round(1) min 255 }, $bmp.data;
}
my $filename = './camelia.ppm';
my Bitmap $b = load-ppm( $filename ) but PGM;
grayscale($b);
'./camelia-gs.pgm'.IO.open(:bin, :w).write: $b.P5;</lang>
See camelia, and camelia-gs images. (converted to .png as .ppm format is not widely supported).
REXX
The input file Lenna50.ppm is a PPM format of
the input file Lenna50.jpg used elsewhere on Rosetta Code.
This REXX program handles alternative delimiters as well as comments within the PPM header. <lang rexx>/*REXX program reads a PPM formatted image file, and creates a gray─scale image of it. */ parse arg iFN oFN /*obtain optional argument from the CL.*/ if iFN== | iFN=="," then iFN= 'Lenna50' /*Not specified? Then use the default.*/ if oFN== | oFN=="," then oFN= 'greyscale' /* " " " " " " */ iFID= iFN'.ppm'; oFID= oFN'.ppm' /*complete the input and output FIDs.*/ call charin iFID, 1, 0 /*set the position of the input file. */ y=charin(iFID, , copies(9, digits() ) ) /*read the entire input file ───► X */ parse var y id 3 c 4 3 width height # pixels /*extract header info from the PPM hdr.*/
LF= 'a'x /*define a comment separator (in hdr).*/ /* ◄─── LF delimiters & comments*/
if c==LF then do; commentEND=pos(LF, y, 4) /*point to the last char in the comment*/ /* ◄─── LF delimiters & comments*/
parse var y =(commentEND) +1 width height # pixels /* ◄─── LF delimiters & comments*/
end /* ◄─── LF delimiters & comments*/
/* [↓] has an alternative delimiter? */ /* ◄─── LF delimiters & comments*/
z=pos(LF, height); if z\==0 then parse var height height =(z) +1 # pixels /* ◄─── LF delimiters & comments*/ z=pos(LF, # ); if z\==0 then parse var # # =(z) +1 pixels /* ◄─── LF delimiters & comments*/ chunk=4000 /*chunk size to be written at one time.*/ LenPixels= length(pixels)
do j=0 for 256; _=d2c(j); @._=j; @@.j=_ /*build two tables for fast conversions*/ end /*j*/
call charout oFID, , 1 /*set the position of the output file. */ call charout oFID, id || width height #' ' /*write the header followed by a blank.*/ !=1
do until !>=LenPixels; $= /*$: partial output string so far.*/
do !=! by 3 for chunk /*chunk: # pixels converted at 1 time.*/
parse var pixels =(!) r +1 g +1 b +1 /*obtain the next RGB of a PPM pixel.*/
if r== then leave /*has the end─of─string been reached? */
_=(.2126*@.r + .7152*@.g + .0722*@.b )%1 /*an integer RGB greyscale of a pixel. */
$=$ || @@._ || @@._ || @@._ /*lump (grey) R G B pixels together. */
end /*!*/ /* [↑] D2C converts decimal ───► char*/
call charout oFID, $ /*write the next bunch of pixels. */
end /*until*/
call charout oFID /*close the output file just to be safe*/ say 'File ' oFID " was created." /*stick a fork in it, we're all done. */</lang>
- output:
File greyscale.ppm was created.
Ruby
Extending Basic_bitmap_storage#Ruby <lang ruby>class Pixmap
# 'open' is a class method
def self.open(filename)
bitmap = nil
File.open(filename, 'r') do |f|
header = [f.gets.chomp, f.gets.chomp, f.gets.chomp]
width, height = header[1].split.map {|n| n.to_i }
if header[0] != 'P6' or header[2] != '255' or width < 1 or height < 1
raise StandardError, "file '#{filename}' does not start with the expected header"
end
f.binmode
bitmap = self.new(width, height)
height.times do |y|
width.times do |x|
# read 3 bytes
red, green, blue = f.read(3).unpack('C3')
bitmap[x,y] = RGBColour.new(red, green, blue)
end
end
end
bitmap
end
end
- create an image: a green cross on a blue background
colour_bitmap = Pixmap.new(20, 30) colour_bitmap.fill(RGBColour::BLUE) colour_bitmap.height.times {|y| [9,10,11].each {|x| colour_bitmap[x,y]=RGBColour::GREEN}} colour_bitmap.width.times {|x| [14,15,16].each {|y| colour_bitmap[x,y]=RGBColour::GREEN}} colour_bitmap.save('testcross.ppm')
- then, convert to grayscale
Pixmap.open('testcross.ppm').to_grayscale!.save('testgray.ppm')</lang>
Scala
Uses the Basic Bitmap Storage and Grayscale Bitmap classes.
See also Task Write a PPM File for save code.
<lang scala>import scala.io._ import scala.swing._ import java.io._ import java.awt.Color import javax.swing.ImageIcon
object Pixmap {
private case class PpmHeader(format:String, width:Int, height:Int, maxColor:Int)
def load(filename:String):Option[RgbBitmap]={
implicit val in=new BufferedInputStream(new FileInputStream(filename))
val header=readHeader
if(header.format=="P6")
{
val bm=new RgbBitmap(header.width, header.height);
for(y <- 0 until bm.height; x <- 0 until bm.width; c=readColor)
bm.setPixel(x, y, c)
return Some(bm)
}
None
}
private def readHeader(implicit in:InputStream)={
var format=readLine
var line=readLine
while(line.startsWith("#")) //skip comments
line=readLine
val parts=line.split("\\s")
val width=parts(0).toInt
val height=parts(1).toInt
val maxColor=readLine.toInt
new PpmHeader(format, width, height, maxColor) }
private def readColor(implicit in:InputStream)=new Color(in.read, in.read, in.read)
private def readLine(implicit in:InputStream)={
var out=""
var b=in.read
while(b!=0xA){out+=b.toChar; b=in.read}
out
}
}</lang>
Usage: <lang scala>object PixmapTest {
def main(args: Array[String]): Unit = {
val img=Pixmap.load("image.ppm").get
val grayImg=BitmapOps.grayscale(img);
Pixmap.save(grayImg, "image_gray.ppm")
val mainframe=new MainFrame(){
title="Test"
visible=true
contents=new Label(){
icon=new ImageIcon(grayImg.image)
}
}
}
}</lang>
Seed7
<lang seed7>$ include "seed7_05.s7i";
include "draw.s7i"; include "color.s7i";
const func PRIMITIVE_WINDOW: getPPM (in string: fileName) is func
result
var PRIMITIVE_WINDOW: aWindow is PRIMITIVE_WINDOW.value;
local
var file: ppmFile is STD_NULL;
var string: line is "";
var integer: width is 0;
var integer: height is 0;
var integer: x is 0;
var integer: y is 0;
var color: pixColor is black;
begin
ppmFile := open(fileName, "r");
if ppmFile <> STD_NULL then
if getln(ppmFile) = "P6" then
repeat
line := getln(ppmFile);
until line = "" or line[1] <> '#';
read(ppmFile, width);
readln(ppmFile, height);
aWindow := newPixmap(width, height);
for y range 0 to pred(height) do
for x range 0 to pred(width) do
pixColor.redLight := ord(getc(ppmFile));
pixColor.greenLight := ord(getc(ppmFile));
pixColor.blueLight := ord(getc(ppmFile));
end for;
end for;
end if;
close(ppmFile);
end if;
end func;</lang>
Tcl
The actual PPM reader is built into the photo image engine: <lang tcl>package require Tk
proc readPPM {image file} {
$image read $file -format ppm
}</lang>
Thus, to read a PPM, convert it to grayscale, and write it back out again becomes this (which requires Tcl 8.6 for try/finally); the PPM reader and writer are inlined because they are trivial at the script level:
<lang tcl>package require Tk
proc grayscaleFile {filename {newFilename ""}} {
set buffer [image create photo]
if {$newFilename eq ""} {set newFilename $filename}
try {
$buffer read $filename -format ppm
set w [image width $buffer]
set h [image height $buffer]
for {set x 0} {$x<$w} {incr x} {
for {set y 0} {$y<$h} {incr y} {
lassign [$buffer get $x $y] r g b
set l [expr {int(0.2126*$r + 0.7152*$g + 0.0722*$b)}]
$buffer put [format "#%02x%02x%02x" $l $l $l] -to $x $y
}
}
$buffer write $newFilename -format ppm
} finally {
image delete $buffer
}
}</lang>
However, the Tk library also has built-in the ability to convert code to grayscale directly during the saving of an image to a file, leading to this minimal solution: <lang tcl>package require Tk
proc grayscaleFile {filename {newFilename ""}} {
set buffer [image create photo]
if {$newFilename eq ""} {set newFilename $filename}
try {
$buffer read $filename -format ppm
$buffer write $newFilename -format ppm -grayscale
} finally {
image delete $buffer
}
}</lang>
UNIX Shell
Ref: Bitmap#UNIX Shell
Add the following functions to the RGBColor_t type <lang bash> function setrgb {
_.r=$1
_.g=$2
_.b=$3
}
function grayscale {
integer x=$(( round( 0.2126*_.r + 0.7152*_.g + 0.0722*_.b ) ))
_.r=$x
_.g=$x
_.b=$x
}</lang>
Add the following function to the Bitmap_t type <lang bash> function grayscale {
RGBColor_t c
for ((y=0; y<_.height; y++)); do
for ((x=0; x<_.width; x++)); do
c.setrgb ${_.data[y][x]}
c.grayscale
_.data[y][x]=$(c.to_s)
done
done
}
function read {
exec 4<"$1"
typeset filetype
read -u4 filetype
if $filetype != "P3" ; then
print -u2 "error: I can only read P3 type PPM files"
else
read -u4 _.width _.height
integer maxval
read -u4 maxval
integer x y r g b
typeset -a bytes
for ((y=0; y<_.height; y++)); do
read -u4 -A bytes
for ((x=0; x<_.width; x++)); do
r=${bytes[3*x+0]}
g=${bytes[3*x+1]}
b=${bytes[3*x+2]}
if (( r > maxval || g > maxval || b > maxval )); then
print -u2 "error: invalid color ($r $g $b), max=$maxval"
return 1
fi
_.data[y][x]="$r $g $b"
done
done
fi
exec 4<&-
}</lang>
Now we can: <lang bash>Bitmap_t c c.read "$HOME/tmp/bitmap.ppm" c.to_s
if $(c.to_s) == $(cat "$HOME/tmp/bitmap.ppm") ; then
echo looks OK
else
echo something is wrong
fi
c.grayscale c.to_s c.write "$HOME/tmp/bitmap_g.ppm"</lang>
Vedit macro language
<lang vedit>// Load a PPM file // @10 = filename // On return: // #10 points to buffer containing pixel data, // #11 = width, #12 = height.
- LOAD_PPM:
File_Open(@10) BOF Search("|X", ADVANCE) // skip "P6"
- 11 = Num_Eval(ADVANCE) // #11 = width
Match("|X", ADVANCE) // skip separator
- 12 = Num_Eval(ADVANCE) // #12 = height
Match("|X", ADVANCE) Search("|X", ADVANCE) // skip maxval (assume 255) Del_Block(0,CP) // remove the header Return</lang>
Example of usage. In addition to LOAD_PPM routine above, you need routine RGB_TO_GRAYSCALE from Grayscale image and routine SAVE_PPM from Write ppm file. <lang vedit>// Load RGB image Reg_Set(10, "|(USER_MACRO)\example.ppm") Call("LOAD_PPM")
// Convert to grayscale
- 10 = Buf_Num
Call("RGB_TO_GRAYSCALE") Buf_Switch(#10) Buf_Quit(OK)
// Convert to RGB Call("GRAYSCALE_TO_RGB")
// Save the image Reg_Set(10, "|(USER_MACRO)\example_gray.ppm") Call("SAVE_PPM")
// Cleanup and exit Buf_Switch(#20) Buf_Quit(OK) return</lang>
XPL0
The simplicity of redirecting an input file on the command line doesn't work for files that contain binary data ($03 will abort a program). Image files larger than 1280x1024 are clipped to the screen dimensions.
<lang XPL0>include c:\cxpl\codes; \intrinsic 'code' declarations
func OpenInFile; \Open for input the file typed on command line int CpuReg, Handle; char CmdTail($80); [CpuReg:= GetReg; Blit(CpuReg(11), $81, CpuReg(12), CmdTail, $7F); \get copy of command line Trap(false); \turn off error trapping Handle:= FOpen(CmdTail, 0); \open named file for input FSet(Handle, ^I); \assign file to input device 3 OpenI(3); \initialize input buffer pointers if GetErr then return false; Trap(true); return true; ];
int C, X, Y, Width, Height, Max, Lum; real Red, Green, Blue; [if not OpenInFile then [Text(0, "File not found"); exit]; if ChIn(3)#^P or ChIn(3)#^6 then [Text(0, "Not P6 PPM file"); exit]; repeat loop [C:= ChIn(3);
if C # ^# then quit;
repeat C:= ChIn(3) until C=$0A\EOL\;
];
until C>=^0 & C<=^9; Backup; \back up so IntIn re-reads first digit Width:= IntIn(3); \(skips any whitespace) Height:= IntIn(3); Max:= IntIn(3) + 1; \(255/15=17; 256/16=16) case of
Width<= 640 & Height<=480: SetVid($112); Width<= 800 & Height<=600: SetVid($115); Width<=1024 & Height<=768: SetVid($118)
other SetVid($11B); \1280x1024 for Y:= 0 to Height-1 do
for X:= 0 to Width-1 do
[Red := float(ChIn(3)*256/Max) * 0.21; \convert color to grayscale
Green:= float(ChIn(3)*256/Max) * 0.72;
Blue := float(ChIn(3)*256/Max) * 0.07;
Lum:= fix(Red) + fix(Green) + fix(Blue);
Point(X, Y, Lum<<16 + Lum<<8 + Lum);
];
X:= ChIn(1); \wait for keystroke SetVid(3); \restore normal text display ]</lang>
Yabasic
<lang Yabasic>sub readPPM(f$) local ff, x, y, t$, dcol$, wid, hei
if f$ = "" print "No PPM file name indicate." : return false
ff = open (f$, "rb") if not ff print "File ", f$, " not found." : return false
input #ff t$, wid, hei, dcol$
if t$ = "P6" then open window wid, hei
for x = 0 to hei - 1 for y = 0 to wid - 1 color peek(#ff), peek(#ff), peek(#ff) dot y, x next y next x
close #ff else print "File is NOT PPM P6 type." : return false end if
return true end sub</lang>
zkl
Read a colored PPM file, convert it (in place) to grayscale and write the new image back to disk under a different name. Sanity checks are omitted.
I used a slightly different image from what is shown, but the results are the same.
<lang zkl>//24-bpp P6 PPM solution: image:=File("lena.ppm","rb").read(); start:=image.find("\n255\n")+5; // Get sizeof PPM header
foreach n in ([start..image.len()-1,3]){ // Transform color triplets
r,g,b:=image[n,3]; // Read colors stored in RGB order l:=(0.2126*r + 0.7152*g + 0.0722*b).toInt(); // Derive luminance image[n,3]=T(l,l,l);
}
File("lenaGrey.ppm","wb").write(image);</lang>
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