Comment 2 for bug 2023189

The files are indeed smaller but the image quality is the same. The only difference is they have been processed to conform to amazon's kindle renderer limitations. That caused the JPEG images to be saved with higher compression. That higher compression does not lead to any visual differences. See for example: the two attached images one from the original epub and the other from the converted azw3 (do not use mobi it is a legacy/obsolete format, azw3 is much higher quality, but regardless with the option to keep original images the images in the MOBI output will be the same as the azw3 output).