Created attachment 6357 [details] Sample A4 PDF When converting a PDF to PNG using the pngalpha device, the background is transparent when the resolution is below a certain value, and white when it's above. The value depends on the page size of the PDF. For example with the test_A4.pdf attached (A4 page size), this command will output the expected transparent background : gs -q -sDEVICE=pngalpha -dBATCH -dNOPAUSE -r160 -sOutputFile=test_A4_160.png test_A4.pdf But this command will output a white background : gs -q -sDEVICE=pngalpha -dBATCH -dNOPAUSE -r161 -sOutputFile=test_A4_161.png test_A4.pdf Any resolution below 160 will produce a transparent background, and any resolution above 161 will produce a white background. When converting an A5 PDF, the background is transparent only for resolutions 227 and lower.
It looks like the transparent background doesn't work when banding is used. Setting a big value to MaxBitmap is a workaround.
I think with recent work on PDF transparency + tags support for both the page and clist (banding) mode, that Michael may have already fixed this, or if not, it will be in areas he has recently considered.
I have still the problems in 9.00 on win.
Still occurs in 9.04 (built from source on Mac OS X). It's not specific to PDF, occurs for postscript also.
This is a duplicate of Bug 692224 *** This bug has been marked as a duplicate of bug 692224 ***