stereo_image_proc disparity image crop

Hi, I am using stereo_image_proc to generate a disparity image. However, I always see a fixed number of columns cropped of on the left side. Since this is fixed, the cropped region is almost half the disparity image in a 160x120 image i.e. almost 80 columns are blank. I dint notice this problem till I went below 640x480 resolution. For a 80x60 image, this becomes even worse. Only a few column pixels are visible. Has anyone experienced the same problem? Is there anyway to rectify this? I tried the same with elas and there is no cropping.