Hi! I’m trying to understand why my files are not printing as I expect, and I’ve noticed a difference between GIMP and Photoshop that I don’t understand.
TLDR: is there a difference between how Adobe products render bitmaps (especially gamma/tone curve) in PDFs compared to GIMP, and if so, can anything be done on the FOSS side to emulate this?
This file: http://caseyconnor.org/pub/calendar/gry.pdf
…has two grey rectangles (overlapping a little). One is a vector element with rgb(120,120,120) and the other is a GIMP-exported PNG with pixels of value rgb(120,120,120) (no color profile embedded, though it doesn’t seem to make a difference anyway.)
If I import that PDF into GIMP, the result is a single solid grey rectangle – i.e. the two areas are indistinguishable, as expected. Same result if I view the PDF in Okular, Firefox, etc. I get the same result if I open it in Adobe Illustrator.
But if I open it in Photoshop, the bitmap rectangle is different (significantly lighter). (I have ancient CS2 versions of Adobe software in a virtual XP machine.)
This is a problem because I’m generating SVGs programatically, including photos I’ve processed in GIMP, converting to PDF with inkscape, and sending them to a printing place to be printed, and the colors of the vector elements aren’t matching the images (I believe the print house is using Adobe products in its printing chain.) It seems as if a very different tonal curve is being applied to the bitmap images.
GIMP’s results seem more intuitive to me: I’m not using any unusual color profiles and would expect the rectangles to match. Yet the end result of this FOSS production chain is that I can’t design stuff and know how it will look when printed: the vector elements don’t match the bitmaps.
Does anyone know why this might be happening? And/or a way to use GIMP/Inkscape/my custom SVG generation/etc to generate files that will print predictably? My first thought was to embed GIMP’s sRGB profile into the SVG in the hopes that it would be picked up downstream, but that may not even be an option: the library I’m using (svgwrite) doesn’t appear to support that, and I’m not sure it’s possible to convert the generated SVG in Inkscape either…
I don’t mean to ask Photoshop questions here; I know it’s not the place. But it’s hard to find an ideal place to ask questions that overlap five pieces of software.
Thanks for any insight.