About C64X imglib IMG_median_3x3

Hi,all

              I am using the evmDM642 with XDS510USB to do the image processing with 720*480 video frames(non interleaved) from the NTSC camera. I enconter a gray cloumn problem on the processed frame when  I invoke the IMG_median_3x3 function and use it the way as the answer from http://e2e.ti.com/support/dsp/davinci_digital_media_processors/f/99/t/61170.aspx. Here is the part of the codes.

unsigned char temp[DISPLAY_IMAGE_WIDTH*DISPLAY_IMAGE_HEIGHT];

...

void Median_Full(int ch)//ch: channel number
{ 
 int j;
 unsigned int denoise_data_offset;

 memset(temp,0,DISPLAY_IMAGE_WIDTH*DISPLAY_IMAGE_HEIGHT);

 denoise_data_offset = 0;
 for(j=0; j<DISPLAY_IMAGE_HEIGHT-2; j++, denoise_data_offset+=DISPLAY_IMAGE_WIDTH)
  IMG_median_3x3(y_buffer_of_channel[ch]+denoise_data_offset, DISPLAY_IMAGE_WIDTH, temp+denoise_data_offset);

 memcpy(y_buffer_of_channel[ch],temp,DISPLAY_IMAGE_WIDTH*DISPLAY_IMAGE_HEIGHT);
}

The first column of each Median_Full(.) processed video frame becomes gray(pixel value=127). Is there some wrong with the codes?

Thanks a lot!