PDF to PNG transparency conversion problem

[jfplante]

Thanks Fred, interesting observation about background transparency vs alpha channel, I'll dig into that direction.

Unfortunately, the "-transparent white" will not work in the general case, since all white in the images gets removed. With this image, i was trying to boil down the generic case problem I am having with other images to the most simple example that was failing.

[fmw42]

floodfill white to transparent would be better, but still may not handle every case, if the border of the main part of the image has any white.

I am not an expert on PDF files, but it does seem strange and somewhat like the Photoshop PSD and TIFF file background transparent. Though I don't really know if this is the case.

[jfplante]

Thanks again, yes there will still be some cases where floodfill would not work, as you mention. I will post here if I find any way out of this problem...

[anthony]

More than likely Photoshop PDF implements its own 'renderer' which avoides the 'white square'.

Ghostscript may not do it right, OR that is exactly the way the PDF does it.

That is either may be assuming a white background which is what PDF is ment for.

Perhaps this 'white square' problem is better directed to the Ghostscript Development Group. I do not however know if they have a wiki, or mailing image or what, but they probably have something. Just a matter of finding the right 'forum' for the developers.


Whatever you decide, please report back here, so others following this thread can know what you did and where you went.

[jfplante]

I created a bug for that: http://bugs.ghostscript.com/show_bug.cgi?id=693024
Will keep you posted.