Wrong CPU output

Discussion created by lupescu_grigore on Nov 28, 2010
Latest reply on Nov 30, 2010 by himanshu.gautam
Simple erosion/dilation alg gives wrong output

I've written a simple program that pipelines 3 kernels ( bitsplicing -> dilation -> erossion)The tested image was Lena (not that it would matter but anyway). I use a threshold of 160 setting the bits to 0 or 1 before dilation/erosion. 

In both dilation and erosion algorithms i get full black/white image on CPU if i set (up,down,left,right) pixels. If i set only 3 of them (eg up,left,right) i get a semi correct response. It is somewhat clear that the algorithm somehow overwrites values as if it would if it were in a for loop working on the same image, but i have 2 images (input,output).

Is this a compiler error or am i missing something ?

LE : 

GPU worked without a problem (HD5470). CPU is Core i3. OpenCL SDK 2.2. Linux Ubuntu 10.10 64 bit


I've added the kernel code just to be clear how i do dilation or erosion ( & insted of | ) though it should make no difference since GPU output is ok whilst CPU is not.


__kernel void dilate(__global int* input,__global int* output,int width,int height)



     uint x = get_global_id(0);

     uint y = get_global_id(1);


// frame width

int frameW=LEVEL;

// frame array

int frameA=LEVEL*LEVEL;


int frameLeft=x;

int frameBottom=y;


int frameTop=((x+frameW) < (width)) ? (x+frameW): (width);

int frameRight=((y+frameW) < (height)) ? (y+frameW): (height);


// get center value (1/0)

int center=input[(frameLeft+1)+width*(frameBottom+1)]/255;


// dilate

output[(frameLeft+1)+width*(frameBottom+1)]=center*255; // center (1,1)


output[(frameLeft+0)+width*(frameBottom+1)]=((input[(frameLeft+0)+width*(frameBottom+1)] /255) | center )*255; // up (0,1)

output[(frameLeft+1)+width*(frameBottom+2)]=((input[(frameLeft+1)+width*(frameBottom+2)] /255) | center )*255; // down (2,1)

output[(frameLeft+1)+width*(frameBottom+0)]=((input[(frameLeft+1)+width*(frameBottom+0)] /255) | center )*255; // left (1,0)

output[(frameLeft+2)+width*(frameBottom+1)]=((input[(frameLeft+2)+width*(frameBottom+1)] /255) | center )*255; // right (1,2)