Invalid Image Format error in overfeat_batch

[sancharidan]

I am using the Overfeat tool to extract image features. However, when I input a set of JPG images using the batch file "overfeat_batch", I got the following error, "Invalid image format (must be 'P6')". I checked the code and saw the step which converts JPG images to PPM images, but I still cannot figure out why this convertion is working well for the JPG images given in the sample folder, but not working properly for my JPG images. Is there any requirement for the image format? Thanks.