Background image is much too dark
Submitted by Thomas Freitag
Assigned to poppler-bugs
Created attachment 119063 PDF with background image that is rendered too dark
The background image in the attached PDF is rendered much too dark with poppler.
The PDF uses a transparency group with fill and stroke opacity of 0.35:
gs /GS1 gfx state dict: << /CA 0.35 /OP false /OPM 0 /Type /ExtGState /ca 0.35 /op false >>
Inside this transparency group a pattern colorspace is used:
cs /Pattern scn /P0
The background image is part of the pattern colorspace, more exactly the pattern colorspace is this image, and before the image is painted the fill opacity is reset to 1:
gs /ca0 gfx state dict: << /Type /ExtGState /ca 1 >> Do /img0
So inside the pattern the fill opacity is 1, but the pattern itself should be set with fill opacity of 1.
In this PDF splash is not able to use its own tilingPatternFill, so it falls back to Gfx::drawForm. But because Gfx::drawForm draws directly in splash bitmap, the fill opacity of the image is used which overwrites the fill opacity of the pattern.
Attachment 119063, "PDF with background image that is rendered too dark":