mtdiff image differencer (useful for animate gifs etc...)
Posted: Tue 09 Oct 2012, 08:54
This is a modification of Mark Tyler's micmp.c example program from the most recent mtcelledit package.
I recalled looking for something like this once and all I found was other people looking, so just in case I need it later, here is mtdiff
Basically all it does is take 2 images of the same size and outputs an image ("diff.png") that shows only the differences (all other pixels get the first color of image 1 which is typically a transparency color) ... nice for reducing the size of animations (this is how webp animations work iirc)
sorry, it only does a static file name, so you'll have to write some kind of script for renaming if you wish to batch process a large number of files.
I recalled looking for something like this once and all I found was other people looking, so just in case I need it later, here is mtdiff
Basically all it does is take 2 images of the same size and outputs an image ("diff.png") that shows only the differences (all other pixels get the first color of image 1 which is typically a transparency color) ... nice for reducing the size of animations (this is how webp animations work iirc)
sorry, it only does a static file name, so you'll have to write some kind of script for renaming if you wish to batch process a large number of files.
Code: Select all
/* micmp.c
Copyright (C) 2007-2008 Mark Tyler
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program in the file COPYING.
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <mtpixel.h>
static void compare_images( mtImage *ia, mtImage *ib ){
mtImage *ic=ia;
int i, j, k, rgb[3][3] = { {0,0,0}, {0,0,0}, {0,0,0} };
unsigned char *a, *b, *c;
a = ia->channel[MTPIXEL_CHANNEL_IMAGE];
b = ib->channel[MTPIXEL_CHANNEL_IMAGE];
c = ic->channel[MTPIXEL_CHANNEL_IMAGE];
if ( ia->width == ib->width && ia->height == ib->height && ia->type == ib->type ){
j = ia->width * ia->height;
if ( ia->type == MTPIXEL_IMAGE_INDEXED ){
for ( i=0; i<j; i++ ){
if ( a[0] != b[0] ) c[0]=b[0];
else c[0]=0;
rgb[0][0] = abs( a[0] - b[0] );
if ( rgb[0][0] > rgb[0][1] ) rgb[0][1] = rgb[0][0];
rgb[0][2] += rgb[0][0];
a ++; b ++; c ++;
}
}
if ( ia->type == MTPIXEL_IMAGE_RGB ){
for ( i=0; i<j; i++ ){
for ( k=0; k<3; k++ ){
rgb[k][0] = abs( a[k] - b[k] );
if ( rgb[k][0] > rgb[k][1] ) rgb[k][1] = rgb[k][0];
rgb[k][2] += rgb[k][0];
}
if ( a[0] == b[0] && a[1] == b[1] && a[2] == b[2] )
{c[0]=0;c[1]=0;c[2]=0;}
else
{c[0]=b[0];c[1]=b[1];c[2]=b[2];}
a += 3; b += 3; c += 3;
}
}
ic->palette.trans=0;
mtpixel_image_save( ic, "diff.png", MTPIXEL_FILE_TYPE_PNG, 5 );
}
}
int main( int argc, char *argv[] ){
mtImage *ia, *ib;
int res = 0;
mtpixel_init();
if ( argc != 3 ){
res = 2;
}else{
ia = mtpixel_image_load( argv[1] );
if ( !ia ){
res = 1;
}else{
ib = mtpixel_image_load( argv[2] );
if ( !ib ){
res = 1;
}else{
compare_images( ia, ib );
mtpixel_image_destroy( ib );
}
mtpixel_image_destroy( ia );
}
}
mtpixel_quit();
return res;
}