(Not sure if I selected the right bugzilla "product component" for this.) I'm seeing different results when using "-sDEVICE=pngalpha" output with PDF input. Example files will be attached to this report.
Created attachment 6453 [details] This PDF can be used to reproduce a regression with output device pngalpha.. Using these commands to produce 2 different PNG files: 1. with GS release 8.71: ------------------------ gswin32.exe ^ -dNOPAUSE -dBATCH ^ -sDEVICE=pngalpha ^ -r72 ^ -sOutputFile=release8.71-pngalpha-nobug.png ^ -f svn-r11502-pngalpha-bug.pdf 2. with GS head (SVN r11502): ----------------------------- C:\downloads\svn.ghostscript.com.ghostpdl\gs\debugbin\gswin32.exe ^ -dNOPAUSE -dBATCH ^ -sDEVICE=pngalpha ^ -r72 ^ -sOutputFile=release8.71-pngalpha-nobug.png ^ -f svn-r11502-pngalpha-bug.pdf
Created attachment 6454 [details] PNG created by GS-8.71
Created attachment 6455 [details] PNG created by GS from current SVN head (r11502)
Original PDF was created by "Adobe InDesign CS2 (4.0)". I extracted the 1st page from it with Ghostscript (hence the changed metadata) to have a smaller testcase.
Thanks for reporting this, it was fixed a few days ago as part of bug 691328.
*** This bug has been marked as a duplicate of bug 691328 ***