root/snippet/gaussian_blur/image.c

#include <math.h>

#include "image.h"

uchar get_pixel( uchar* src, int x, int y, int width, int height  ){

#ifdef ZERO_PADDING
        if( x < 0 || x >= width || y < 0 || y >= height )
                return 0;
        else 
                return src[y*width+x];
#else
        if( x < 0 )
                x = 0;
        else if( x >= width )
                x = width-1;

        if( y < 0 )
                y = 0;
        else if( y >= height )
                y = height-1;

        return src[y*width+x];
#endif

}

uchar clip( double pixel ){

        pixel = floor( pixel+0.5 );
        
        if( pixel >= 255 )
                return 255;
        
        else if( pixel < 0 )
                return 0;
        
        else
                return (unsigned char)pixel;
        
}

void difference( uchar* dst, uchar* s1, uchar* s2, int width, int height ){

        int i, j;
        int diff;
        
        for( j = 0 ; j < height ; j++ ){
                for( i = 0 ; i < width ; i++ ){
                        if( (diff = s1[j*width+i] - s2[j*width+i]) < 0 )
                                diff = -diff;
                        
                        dst[j*width+i] = diff;
                }
        }
}