# Odered Bayer Dithering

Hello!,
I am trying to apply ordered bayer dithering algo on a image and I am not able to get the result.
The algo is :–

``````foreach y
foreach x
oldpixel := pixel[x][y] + (pixel[x][y] * threshold_map_4x4[x mod 4][y mod 4])
newpixel := find_closest_palette_color(oldpixel)
pixel[x][y] := newpixel
``````

My code :–

``````void testApp::setup(){

int factor = 0;
float array[4][4] = {{1,9,3,11},{13,5,15,7},{4,12,2,10},{16,8,14,6}};

for(int i = 0 ; i<4;i++){
for(int j = 0 ; j<4;j++){
array[i][j] = array[i][j]/17;
}
}

img1.resize(999,999);
img1.update();

img2 = img1;

pix = img1.getPixels();
pix2 = img2.getPixels();

for(int k  = 0 ; k < 999 ; k++){
for(int j = 0 ; j < 999*3 ; j+=3){

factor = array[k%4][j%4];
pix2[k*999 + j] +=  ( pix2[k*999 + j]  * factor );
pix2[k*999 + j + 1] +=  ( pix2[k*999 + j + 1]  * factor );
pix2[k*999 + j + 2] +=  ( pix2[k*999 + j + 2]  * factor );

pix[k*999 + j] = ( pix2[k*999 +j] + 128 ) / 256 ;
pix[k*999 + j+1] = ( pix2[k*999 +j+1] + 128 ) / 256 ;
pix[k*999 + j+2] = ( pix2[k*999 +j+2] + 128 ) / 256 ;

}
}

img1.update();

}

//--------------------------------------------------------------
void testApp::update(){

}

//--------------------------------------------------------------
void testApp::draw(){

img1.draw(0,0);

}
``````

wikipedia :-- http://en.wikipedia.org/wiki/Ordered_dithering

What is wrong with my code ? Thanks!

I recall OpenCV had some methods to do that

I don’t want to go through the whole opencv docs ,it will simply make the code more complicated .Cant I do it simply by using just ofImage and the algo ?
Thanks!