Bitmap/Read an image through a pipe
This task is the opposite of the PPM conversion through a pipe. In this task, using a delegate tool (like cjpeg, one of the netpbm package, or convert of the ImageMagick package) we read an image file and load it into the data storage type defined here. We can also use the code from Read ppm file, so that we can use PPM format like a (natural) bridge between the foreign image format and our simple data storage.
You are encouraged to solve this task according to the task description, using any language you may know.
AutoHotkey
Uses StdoutTovar.ahk <lang AutoHotkey>ppm := Run("cmd.exe /c convert lena50.jpg ppm:-")
; pipe in from imagemagick
img := ppm_read("", 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
- include run.ahk ; http://www.autohotkey.com/forum/viewtopic.php?t=16823
</lang>
C
Here I've used convert by ImageMagick. It is up to the program to understand the source file type; in this way, we can read theoretically any image format ImageMagick can handle. The get_ppm function defined in Read ppm file is used.
<lang c>image read_image(const char *name);</lang>
<lang c>#include "imglib.h"
- define MAXCMDBUF 100
- define MAXFILENAMELEN 256
- define MAXFULLCMDBUF (MAXCMDBUF + MAXFILENAMELEN)
image read_image(const char *name) {
FILE *pipe; char buf[MAXFULLCMDBUF]; image im; FILE *test = fopen(name, "r"); if ( test == NULL ) { fprintf(stderr, "cannot open file %s\n", name); return NULL; } fclose(test); snprintf(buf, MAXFULLCMDBUF, "convert \"%s\" ppm:-", name); pipe = popen(buf, "r"); if ( pipe != NULL ) { im = get_ppm(pipe); pclose(pipe); return im; } return NULL;
}</lang>
Go
This example uses convert to convert the test image for the flood fill task. It reads through the pipe as required for this task, then writes as a .ppm file convenient for the flood fill task. <lang go>package main
// Files required to build supporting package raster are found in: // * Bitmap // * Read a PPM file // * Write a PPM file
import (
"log" "os/exec" "raster"
)
func main() {
c := exec.Command("convert", "Unfilledcirc.png", "-depth", "1", "ppm:-") pipe, err := c.StdoutPipe() if err != nil { log.Fatal(err) } if err = c.Start(); err != nil { log.Fatal(err) } b, err := raster.ReadPpmFrom(pipe) if err != nil { log.Fatal(err) } if err = b.WritePpmFile("Unfilledcirc.ppm"); err != nil { log.Fatal(err) }
}</lang>
Julia
<lang julia>using Images, FileIO
img = load("data/bitmapOutputTest.jpg") save("data/bitmapOutputTest.ppm", img)</lang>
Kotlin
The code for this is similar to that for the Bitmap/Read a PPM file task except that the .jpg file is converted via a pipe to .ppm format using the ImageMagick 'convert' tool and stored in a BasicBitmapStorage object. It is then converted to grayscale and saved back to disk as a .jpg file. <lang scala>// Version 1.2.40
import java.awt.Color import java.awt.Graphics import java.awt.image.BufferedImage 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_piped.jpg, created in the // Bitmap/PPM conversion through a pipe task val pb = ProcessBuilder("convert", "output_piped.jpg", "ppm:-") pb.directory(null) pb.redirectOutput(ProcessBuilder.Redirect.PIPE) val proc = pb.start() val pStdOut = proc.inputStream val pbis = PushbackInputStream(pStdOut, 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_piped_gray.jpg") ImageIO.write(bbs.image, "jpg", grayFile) } }
}</lang>
Lua
Uses Bitmap class here, with an RGB tuple pixel representation, and the rudimentary PPM support here, and the Lenna image here.
First, the loadPPM()
method is altered to allow passing an existing file handle:
<lang lua>function Bitmap:loadPPM(filename, fp)
if not fp then fp = io.open(filename, "rb") end if not fp then return end local head, width, height, depth, tail = fp:read("*line", "*number", "*number", "*number", "*line") self.width, self.height = width, height self:alloc() for y = 1, self.height do for x = 1, self.width do self.pixels[y][x] = { string.byte(fp:read(1)), string.byte(fp:read(1)), string.byte(fp:read(1)) } end end fp:close()
end</lang>
Then, for the actual "read-from-pipe" task, a Lua environment that supports io.popen()
is required:
<lang lua>local bitmap = Bitmap(0,0)
fp = io.popen("magick Lenna100.jpg ppm:-", "rb")
bitmap:loadPPM(nil, fp)
bitmap:savePPM("Lenna100.ppm") -- just as "proof"</lang>
Mathematica/Wolfram Language
Based off the Julia program. <lang Mathematica>Export["data/bitmapOutputTest.ppm",Import["data/bitmapOutputTest.jpg"]];</lang>
Nim
Using "jpegtopnm" from Netpbm suite. Input is a JPEG file and result (the PPM file) is sent to stdout. The procedure "readPPM" reads directly from the stream and build the image container.
<lang Nim>import bitmap import osproc import ppm_read import streams
- Launch Netpbm "jpegtopnm".
- Input is taken from "input.jpeg" and result sent to stdout.
let p = startProcess("jpegtopnm", args = ["input.jpeg"], options = {poUsePath}) let stream = FileStream(p.outputStream()) let image = stream.readPPM() echo image.w, " ", image.h p.close()</lang>
OCaml
The read_ppm
function of the page read ppm file and used by the code below would need to be changed to take as parameter an input channel instead of the filename.
<lang ocaml>let read_image ~filename =
if not(Sys.file_exists filename) then failwith(Printf.sprintf "the file %s does not exist" filename); let cmd = Printf.sprintf "convert \"%s\" ppm:-" filename in let ic, oc = Unix.open_process cmd in let img = read_ppm ~ic in (img)
- </lang>
Phix
Uses the demo\rosetta\viewppm.exw utility to accomplish this task.
The returned data is raw binary, so you can either write it direct or chuck it through read_ppm/write_ppm.
<lang Phix>-- demo\rosetta\Bitmap_Read_an_image_through_a_pipe.exw
requires("0.8.4")
include builtins\pipeio.e
include ppm.e -- read_ppm(), write_ppm()
sequence pipes = repeat(0,3) pipes[PIPOUT] = create_pipe(INHERIT_READ)
-- Create the child process, with replacement stdout. string cmd = sprintf("%s viewppm -load test.jpg",{get_interpreter(true)}) atom hProc = system_exec(cmd, 12, pipes),
hPipe = pipes[PIPOUT][READ_PIPE]
string ppm = read_from_pipe(hPipe, hProc) while true do
object chunk = read_from_pipe(hPipe, hProc) if chunk=-1 then exit end if ppm &= chunk
end while
pipes = close_handles(pipes)
if 0 then
sequence img = read_ppm(ppm,bText:=true) write_ppm("Lenapipe.ppm", img)
else -- or
integer fn = open("Lenapipe.ppm","wb") puts(fn,ppm) close(fn)
end if</lang>
PicoLisp
<lang PicoLisp>(setq *Ppm (ppmRead '("convert" "img.jpg" "ppm:-")))</lang>
Python
<lang Python> """ Adapted from https://stackoverflow.com/questions/26937143/ppm-to-jpeg-jpg-conversion-for-python-3-4-1 Requires pillow-5.3.0 with Python 3.7.1 32-bit on Windows. Sample ppm graphics files from http://www.cs.cornell.edu/courses/cs664/2003fa/images/ """
from PIL import Image
- boxes_1.jpg is the jpg version of boxes_1.ppm
im = Image.open("boxes_1.jpg") im.save("boxes_1v2.ppm") </lang> Does not need to pipe through a conversion utility because the Pillow module does the conversion.
Racket
<lang racket>
(define (read-ppm port)
(parameterize ([current-input-port port]) (define magic (read-line)) (match-define (list w h) (string-split (read-line) " ")) (define width (string->number w)) (define height (string->number h)) (define maxcol (string->number (read-line))) (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-byte)) (define green (read-byte)) (define blue (read-byte)) (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))
(define (image->bmp filename)
(define command (format "convert ~a ppm:-" filename)) (match-define (list in out pid err ctrl) (process command)) (define bmp (read-ppm in)) (close-input-port in) (close-output-port out) bmp)
(image->bmp "input.jpg")</lang>
Raku
(formerly Perl 6)
Uses pieces from Bitmap and Read a PPM file tasks. Included here to make a complete, runnable program.
Uses imagemagick convert to pipe the image in.
<lang perl6>class Pixel { has UInt ($.R, $.G, $.B) } class Bitmap {
has UInt ($.width, $.height); has Pixel @.data;
}
role PPM {
method P6 returns Blob {
"P6\n{self.width} {self.height}\n255\n".encode('ascii') ~ Blob.new: flat map { .R, .G, .B }, self.data
}
}
sub getline ( $proc ) {
my $line = '#'; # skip comment when reading a .png $line = $proc.out.get while $line.substr(0,1) eq '#'; $line;
}
my $filename = './camelia.png';
my $proc = run 'convert', $filename, 'ppm:-', :enc('ISO-8859-1'), :out;
my $type = getline($proc); my ($width, $height) = getline($proc).split: ' '; my $depth = getline($proc);
my Bitmap $b = Bitmap.new( width => $width.Int, height => $height.Int) but PPM;
$b.data = $proc.out.slurp.ords.rotor(3).map:
{ Pixel.new(R => .[0], G => .[1], B => .[2]) };
'./camelia.ppm'.IO.open(:bin, :w).write: $b.P6;</lang>
See camelia image here.
Ruby
Uses Raster graphics operations/Ruby.
<lang ruby># frozen_string_literal: true
require_relative 'raster_graphics'
class Pixmap
def self.read_ppm(ios) format = ios.gets.chomp width, height = ios.gets.chomp.split.map(&:to_i) max_colour = ios.gets.chomp
if !PIXMAP_FORMATS.include?(format) || (width < 1) || (height < 1) || (max_colour != '255') ios.close raise StandardError, "file '#{filename}' does not start with the expected header" end ios.binmode if PIXMAP_BINARY_FORMATS.include?(format)
bitmap = new(width, height) height.times do |y| width.times do |x| # read 3 bytes red, green, blue = case format when 'P3' then ios.gets.chomp.split when 'P6' then ios.read(3).unpack('C3') end bitmap[x, y] = RGBColour.new(red, green, blue) end end ios.close bitmap end
def self.open(filename) read_ppm(File.open(filename, 'r')) end
def self.open_from_jpeg(filename) read_ppm(IO.popen("convert jpg:#{filename} ppm:-", 'r')) end
end
bitmap = Pixmap.open_from_jpeg('foto.jpg') bitmap.save('foto.ppm') </lang>
Tcl
<lang tcl>package require Tk
proc magickalReadImage {bufferImage fileName} {
set f [open |[list convert [file normalize $fileName] ppm:-] "rb"] try { $bufferImage put [read $f] -format ppm } finally { close $f }
}</lang>
zkl
Uses the PPM class from http://rosettacode.org/wiki/Bitmap/Bresenham%27s_line_algorithm#zkl
Using the convert utility by ImageMagick: <lang zkl>p:=System.popen(0'|convert "fractalTree.jpg" ppm:-|,"r"); img:=PPM.readPPM(p); p.close();</lang>