If MagickImageInfo can determine the Compression without loading the entire image, that will solve the issue. Then I will be able to know that this image should be processed further. These images come from our customers and we have no idea what will be in them. Consequently, if something is "wrong" with the image for our purposes, loading only the headers to decide is the most efficient way.
We have a vendor/third-party rendering program that uses GDI+ to read images and is a black box. So, I have to fix these images before that process tries to use the image. If I understand your last paragraph, detecting the Compression beforehand avoids a catch-22 -- it's too inefficient to read the entire image all the time (since JPG is what we get the most) and as you indicate earlier it wouldn't matter if I read it because there's nothing to detect with compression before decoding.
Hope that makes sense, and thanks for your help.
We have a vendor/third-party rendering program that uses GDI+ to read images and is a black box. So, I have to fix these images before that process tries to use the image. If I understand your last paragraph, detecting the Compression beforehand avoids a catch-22 -- it's too inefficient to read the entire image all the time (since JPG is what we get the most) and as you indicate earlier it wouldn't matter if I read it because there's nothing to detect with compression before decoding.
Hope that makes sense, and thanks for your help.