I have been trying to implement a simple Gaussian blur algorithm, for my image editing program. However, I have been having some trouble making this work, and I think the problem lies in the below snippet:
for( int j = 0; j < pow( kernel_size, 2 ); j++ )
{
int idx = ( i + kx + ( ky * img.width ));
//Try and overload this whenever possible
valueR += ( img.p_pixelArray[ idx ].r * kernel[ j ] );
valueG += ( img.p_pixelArray[ idx ].g * kernel[ j ] );
valueB += ( img.p_pixelArray[ idx ].b * kernel[ j ] );
if( kx == kernel_limit )
{
kx = -kernel_limit;
ky++;
}
else
{
kx++;
}
}
kx = -kernel_limit;
ky = -kernel_limit;
A brief explanation of the code above: kernel size is the size of the kernel (or matrix) generated by the Gaussian blur formula. kx and ky are variables to be used for iterating over the kernel. i is the parent loop, that nests this one, and goes over every pixel in the image. Each value variable simply holds a float R, G, or B value, and is used afterwards to obtain the final result. The if-else is used to increase kx and ky. idx is used to find the correct pixel. kernel limit is a variable set to
(*kernel size* - 1) / 2
So I can have kx going from -1 ( with a 3x3 kernel ) to +1, and the same thing with ky. I think the problem lies with the line
int idx = ( i + kx + ( ky * img.width ));
But I am not sure. The image I get is:
As can be seen, the color is blurred in a diagonal direction, and looks more like some kind of motion blur than Gaussian blur. If someone could help out, I would be very grateful.
EDIT: The way I fill the kernel is as follows:
for( int i = 0; i < pow( kernel_size, 2 ); i++ )
{
// This. Is. Lisp.
kernel[i] = (( 1 / ( 2 * pi * pow( sigma, 2 ))) * pow (e, ( -((( pow( kx, 2 ) + pow( ky, 2 )) / 2 * pow( sigma, 2 ))))));
if(( kx + 1 ) == kernel_size )
{
kx = 0;
ky++;
}
else
{
kx++;
}
}
kx
andky
at every iteration and you'd always get the same value foridx
. Also, can you show how you fillkernel
, maybe that's what's wrong. – sgvd