I work in the manga/webtoon localization industry, and all files received from the original publishers that aren't TIFF are INDD or PSD. There is no choice but to use photoshop and indesign. Recently, I had to cough up money for the pricey indesign server in order to be able to ingest the .indd files en masse. There's no other choice. At first I thought I could do it with a mix of humans converting to .idml (the xml zip slightly less proprietary format) and my own python!... but you still need indesign for that first part, and after weeks of python, I gave up trying to parse that nasty mess that is idml. Now I run an ugly indesign js script that also talks to photoshop via bridge to create workabke files. It's disgusting and I pay the adobe tax, but it works. P.S. protip: never export images from indesign using any other option besides PDF, Indesign's built in image renders are awful for manga. Tune all the pdf settings so there is no quality loss, then "print" the pdf to image using ghostscript