Percentage difference between images: Difference between revisions
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Close (F1); |
Close (F1); |
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Close (F2);</lang> |
Close (F2);</lang> |
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=={{header|C}}== |
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int main() |
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The <tt>read_image</tt> function is from [[Read image file through a pipe|here]]. |
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<lang c>#include <stdio.h> |
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/* #include "imglib.h" */ |
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#define RED_C 0 |
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#define GREEN_C 1 |
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#define BLUE_C 2 |
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#define GET_PIXEL(IMG, X, Y) ((IMG)->buf[ (Y) * (IMG)->width + (X) ]) |
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int main(int argc, char **argv) |
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{ |
{ |
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int s=0; |
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int i=0,x[3],n,a,b, count=0; |
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double totalDiff = 0.0; |
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printf("ta toogoo oruul\n"); |
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unsigned int x, y; |
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for(a=100; a<1000; a++) |
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{ |
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fprintf(stderr, "usage:\n%s FILE1 FILE2\n", argv[0]); |
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} |
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im1 = read_image(argv[1]); |
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if ( im1 == NULL ) exit(1); |
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im2 = read_image(argv[2]); |
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if ( im2 == NULL ) { free_img(im1); exit(1); } |
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if ( (im1->width != im2->width) || (im1->height != im2->height) ) |
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{ |
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fprintf(stderr, "width/height of the images must match!\n"); |
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} else { |
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/* BODY: the "real" part! */ |
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for(x=0; x < im1->width; x++) |
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{ |
{ |
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b=a; |
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x[0]=b%10; |
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b=b/10; |
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totalDiff += fabs( GET_PIXEL(im1, x, y)[RED_C] - GET_PIXEL(im2, x, y)[RED_C] ) / 255.0; |
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x[1]=b%10; |
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totalDiff += fabs( GET_PIXEL(im1, x, y)[GREEN_C] - GET_PIXEL(im2, x, y)[GREEN_C] ) / 255.0; |
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b=b/10; |
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totalDiff += fabs( GET_PIXEL(im1, x, y)[BLUE_C] - GET_PIXEL(im2, x, y)[BLUE_C] ) / 255.0; |
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x[2]=b%10; |
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s=x[0]+x[1]+x[2]; |
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if(s==n){ |
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printf("%lf\n", 100.0 * totalDiff / (double)(im1->width * im1->height * 3) ); |
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count++; |
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/* BODY ends */ |
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} |
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} |
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} printf("niit"); |
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printf(" %d too baina\n",count); |
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free_img(im2); |
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system("pause"); |
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}</lang> |
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} |
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The output on Lenna is: |
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<pre> |
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1.625587 |
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</pre> |
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=={{header|Common Lisp}}== |
=={{header|Common Lisp}}== |
Revision as of 06:38, 1 December 2009
You are encouraged to solve this task according to the task description, using any language you may know.
Compute the percentage of difference between 2 JPEG images of the same size. Alternatively, compare two bitmaps as defined in basic bitmap storage.
Useful for comparing two JPEG images saved with a different compression ratios.
You can use these pictures for testing:
The expected difference for these two images is 1.62125%
Ada
<lang ada>type Count is mod 2**64;</lang> 1-norm distance in the luminance space: <lang ada>function "-" (Left, Right : Luminance) return Count is begin
if Left > Right then return Count (Left) - Count (Right); else return Count (Right) - Count (Left); end if;
end "-";</lang> 1-norm distance in the color space multiplied to 3: <lang ada>function "-" (Left, Right : Pixel) return Count is begin
return (Left.R - Right.R) + (Left.G - Left.G) + (Left.B - Right.B);
end "-";</lang> Mean of 1-norm distances. Constraint_Error is propagated when images have different size. <lang ada>function Diff (Left, Right : Image) return Float is
Offs_I : constant Integer := Right'First (1) - Left'First (1); Offs_J : constant Integer := Right'First (2) - Left'First (2); Sum : Count := 0;
begin
if Left'Length (1) /= Right'Length (1) or else Left'Length (2) /= Right'Length (2) then raise Constraint_Error; end if; for I in Left'Range (1) loop for J in Left'Range (2) loop Sum := Sum + (Left (I, J) - Right (I + Offs_I, J + Offs_J)); end loop; end loop; return Float (Sum) / (3.0 * Float (Left'Length (1) * Left'Length (2)));
end Diff;</lang> Example of use: <lang ada> F1, F2 : File_Type; begin
Open (F1, In_File, "city.ppm"); Open (F2, In_File, "city_emboss.ppm"); Ada.Text_IO.Put_Line ("Diff" & Float'Image (Diff (Get_PPM (F1), Get_PPM (F2)))); Close (F1); Close (F2);</lang>
- include<stdio.h>
- include<stdlib.h>
int main() {
int s=0; int i=0,x[3],n,a,b, count=0; printf("ta toogoo oruul\n"); scanf("%d",&n); for(a=100; a<1000; a++) { b=a; x[0]=b%10; b=b/10; x[1]=b%10; b=b/10; x[2]=b%10; s=x[0]+x[1]+x[2]; if(s==n){ count++; } } printf("niit"); printf(" %d too baina\n",count); system("pause");
}
Common Lisp
This is based upon the C version. Strangely enough, the percentage is 1.77% which is off by about a tenth of a percent.
<lang lisp>(require 'cl-jpeg)
- the JPEG library uses simple-vectors to store data. this is insane!
(defun compare-images (file1 file2)
(declare (optimize (speed 3) (safety 0) (debug 0))) (multiple-value-bind (image1 height width) (jpeg:decode-image file1) (let ((image2 (jpeg:decode-image file2))) (loop for i of-type (unsigned-byte 8) across (the simple-vector image1) for j of-type (unsigned-byte 8) across (the simple-vector image2) sum (the fixnum (abs (- i j))) into difference of-type fixnum finally (return (coerce (/ difference width height #.(* 3 255)) 'double-float))))))
CL-USER> (* 100 (compare-images "Lenna50.jpg" "Lenna100.jpg")) 1.774856467652165d0</lang>
E
By dividing only at the end, we work with integers only as the sum and avoid floating-point error from adding small numbers (per-pixel difference) to large ones (sum of differences).
<lang e>def imageDifference(a, b) {
require(a.width() == b.width()) require(a.height() == b.height()) def X := 0..!(a.width()) def Y := 0..!(a.height()) var sumByteDiff := 0 for y in Y { for x in X { def ca := a[x, y] def cb := b[x, y] sumByteDiff += (ca.rb() - cb.rb()).abs() \ + (ca.gb() - cb.gb()).abs() \ + (ca.bb() - cb.bb()).abs() } println(y) } return sumByteDiff / (255 * 3 * a.width() * a.height())
}
def imageDifferenceTask() {
println("Read 1...") def a := readPPM(<import:java.io.makeFileInputStream>(<file:Lenna50.ppm>)) println("Read 2...") def b := readPPM(<import:java.io.makeFileInputStream>(<file:Lenna100.ppm>)) println("Compare...") def d := imageDifference(a, b) println(`${d * 100}% different.`)
}</lang>
The result on the provided images is 1.6255930981604882%.
Forth
<lang forth>: pixel-diff ( pixel1 pixel2 -- n )
over 255 and over 255 and - abs >r 8 rshift swap 8 rshift over 255 and over 255 and - abs >r 8 rshift swap 8 rshift - abs r> + r> + ;
- bdiff ( bmp1 bmp2 -- fdiff )
2dup bdim rot bdim d<> abort" images not comparable" 0e ( F: total diff ) dup bdim * >r ( R: total pixels ) bdata swap bdata r@ 0 do over @ over @ pixel-diff 0 d>f f+ cell+ swap cell+ loop 2drop r> 3 * 255 * 0 d>f f/ ;
- .bdiff ( bmp1 bmp2 -- )
cr bdiff 100e f* f. ." percent different" ;</lang>
Fortran
<lang fortran>program ImageDifference
use RCImageBasic use RCImageIO
implicit none
integer, parameter :: input1_u = 20, & input2_u = 21
type(rgbimage) :: lenna1, lenna2 real :: totaldiff
open(input1_u, file="Lenna100.ppm", action="read") open(input2_u, file="Lenna50.ppm", action="read") call read_ppm(input1_u, lenna1) call read_ppm(input2_u, lenna2) close(input1_u) close(input2_u)
totaldiff = sum( (abs(lenna1%red - lenna2%red) + & abs(lenna1%green - lenna2%green) + & abs(lenna1%blue - lenna2%blue)) / 255.0 )
print *, 100.0 * totaldiff / (lenna1%width * lenna1%height * 3.0)
call free_img(lenna1) call free_img(lenna2)
end program ImageDifference</lang>
This gives 1.6555154.
MAXScript
<lang maxscript>fn diffImages = ( local img1 = selectBitmap caption:"Select Image 1" local img2 = selectBitmap caption:"Select Image 2" local totalDiff = 0 for i in 0 to (img1.height-1) do ( local img1Row = getPixels img1 [0, i] img1.width local img2Row = getPixels img2 [0, i] img2.width
for j in 1 to img1.width do ( totalDiff += (abs (img1Row[j].r - img2Row[j].r)) / 255.0 totalDiff += (abs (img1Row[j].g - img2Row[j].g)) / 255.0 totalDiff += (abs (img1Row[j].b - img2Row[j].b)) / 255.0 ) ) format "Diff: %\%\n" (totalDiff / ((img1.width * img1.height * 3) as float) * 100) )</lang>
J
<lang j> require 'media/image3'
'Lenna50.jpg' (100 * +/@,@:|@:- % 255 * */@$@])&:read_jpeg_ima3_ 'Lenna100.jpg'
1.62559</lang>
OCaml
<lang ocaml>#! /usr/bin/env ocaml
- directory "+glMLite/"
- load "jpeg_loader.cma"
- load "bigarray.cma"
open Jpeg_loader
let () =
let img1, width1, height1, col_comp1, color_space1 = load_img (Filename Sys.argv.(1)) and img2, width2, height2, col_comp2, color_space2 = load_img (Filename Sys.argv.(2)) in
assert(width1 = width2); assert(height1 = height2); assert(col_comp1 = col_comp2); (* number of color components *) assert(color_space1 = color_space2);
let img1 = Bigarray.array3_of_genarray img1 and img2 = Bigarray.array3_of_genarray img2 in
let sum = ref 0.0 and num = ref 0 in
for x=0 to pred width1 do for y=0 to pred height1 do for c=0 to pred col_comp1 do let v1 = float img1.{x,y,c} and v2 = float img2.{x,y,c} in let diff = (abs_float (v1 -. v2)) /. 255. in sum := diff +. !sum; incr num; done; done; done;
let diff_percent = !sum /. float !num in Printf.printf " diff: %f percent\n" diff_percent;
- </lang>
Python
<lang python>from itertools import izip import Image
i1 = Image.open("image1.jpg") i2 = Image.open("image2.jpg") assert i1.mode == i2.mode, "Different kinds of images." assert i1.size == i2.size, "Different sizes."
pairs = izip(i1.getdata(), i2.getdata()) if len(i1.getbands()) == 1:
# for gray-scale jpegs dif = sum(abs(p1-p2) for p1,p2 in pairs)
else:
dif = sum(abs(c1-c2) for p1,p2 in pairs for c1,c2 in zip(p1,p2))
ncomponents = i1.size[0] * i1.size[1] * 3 print "Difference (percentage):", (dif / 255.0 * 100) / ncomponents</lang>
Ruby
uses the raster_graphics
library
<lang ruby>require 'raster_graphics'
class RGBColour
# the difference between two colours def -(a_colour) (@red - a_colour.red).abs + (@green - a_colour.green).abs + (@blue - a_colour.blue).abs end
end
class Pixmap
# the difference between two images def -(a_pixmap) if @width != a_pixmap.width or @height != a_pixmap.height raise ArgumentError, "can't compare images with different sizes" end sum = 0 each_pixel {|x,y| sum += self[x,y] - a_pixmap[x,y]} Float(sum) / (@width * @height * 255 * 3) end
end
lenna50 = Pixmap.open_from_jpeg('Lenna50.jpg') lenna100 = Pixmap.open_from_jpeg('Lenna100.jpg')
puts "difference: %.5f%%" % (100.0 * (lenna50 - lenna100))</lang>
produces:
difference: 1.62559%
Tcl
This version uses the Img package, but only to provide a convenient JPEG loader; it's utterly unnecessary for the process of actually computing the difference. <lang tcl>package require Tk
proc imageDifference {img1 img2} {
if {
[image width $img1] != [image width $img2] || [image height $img1] != [image height $img2]
} then {
return -code error "images are different size"
} set diff 0 for {set x 0} {$x<[image width $img1]} {incr x} {
for {set y 0} {$y<[image height $img1]} {incr y} { lassign [$img1 get $x $y] r1 g1 b1 lassign [$img2 get $x $y] r2 g2 b2 incr diff [expr {abs($r1-$r2)+abs($g1-$g2)+abs($b1-$b2)}] }
} expr {$diff/double($x*$y*3*255)}
}
- Package only used for JPEG loader
package require Img image create photo lenna50 -file lenna50.jpg image create photo lenna100 -file lenna100.jpg puts "difference is [expr {[imageDifference lenna50 lenna100]*100.}]%" exit ;# Need explicit exit here; don't want a GUI</lang> It produces this output:
difference is 1.6255930981604882%
Vedit macro language
This implementation compares two BMP images.
<lang vedit>Chdir("|(USER_MACRO)\Rosetta\data") File_Open("Lenna50.bmp", BROWSE)
- 10 = Buf_Num // #10 = buffer for 1st image
File_Open("Lenna100.bmp", BROWSE)
- 20 = Buf_Num // #20 = buffer for 2nd image
Goto_Pos(10) // offset to pixel data Goto_Pos(Cur_Char + Cur_Char(1)*256) Buf_Switch(#10) Goto_Pos(10) Goto_Pos(Cur_Char + Cur_Char(1)*256)
- 15 = 0 // #15 = difference
- 16 = 0 // #16 = total number of samples
While(!At_EOF) {
#11 = Cur_Char; Char Buf_Switch(#20) #21 = Cur_Char; Char #15 += abs(#11-#21) #16++ Buf_Switch(#10)
}
- 19 = #15 / (#16*256/100000)
M("Sum of diff: ") NT(#15) M("Total bytes: ") NT(#16) M("Difference: ") NT(#19/1000,LEFT+NOCR) M(".") NT(#19%1000,LEFT+NOCR) M("%\n")
Buf_Switch(#10) Buf_Quit(OK) Buf_Switch(#20) Buf_Quit(OK)</lang>
Output, when comparing the Lenna images that were converted to BMP:
Sum of diff: 3259967 Total bytes: 786432 Difference: 1.619%