-extract-images for CMYK and multichannel

[zollybig]

-extract-images is a great option, and merge-masks is even better. However, there are complications when using CMYK images, as everything is converted to RGB during export. I understand that this is due to the use of PNG, but it would be great to be able to extract images in their original format, including multichannel.

cpdf 2_flat.pdf -list-images
17, 1, /X1, 890, 906, 60568, 8, /DeviceCMYK, /FlateDecode, NoMask, none

but -extract-images returns RGB image (PNG)

[johnwhitington]

Thanks. Yes, all images are converted to RGB even when writing as PNM. So we can definitely do better.

[johnwhitington]

See also johnwhitington/cpdf-source#451