Questions and postings pertaining to the usage of ImageMagick regardless of the interface. This includes the command-line utilities, as well as the C and C++ APIs. Usage questions are like "How do I use ImageMagick to create drop shadows?".
Try identify -verbose against your 5.2.2 and 6.0.7 JPEG images to see if you can account for the differences. Verify if it is the image profiles that account for the different image sizes.
ImageMagick 6 series is not configured with a 100 compression quality. Instead it estimates the compression quality of the input JPEG image and uses it when writing a new JPEG. You can of course set an explicit compression quality of say 75 with -quality 75.
