Thread subject: sK1 Project :: Converting to PDF with transparent bitmaps (alpha channel)

Posted by jonata on 24-08-2010 17:35

Hi there

I want to know if it is possible to render into the PDF transparent bitmaps. It seems that reportlab and PIL already support it.

Are there planes to do it in uniconvertor roadmap? This is just a question of install a newer version of this libraries?

Thanks for the attention.

Edited by jonata on 27-08-2010 14:37

Posted by igor on 27-08-2010 15:10


Sorry for delay in responding.

Actually RGBA images are already supported by UniConvertor/sK1. But CMYKA images is not yet. The same is true for PIL and ReportLab packages. To resolve this issue we need fixing internal copies of PIL and ReportLab to implement TIFF support for CMYKA images.

Posted by jonata on 27-08-2010 20:11

No problem Igor. Thanks for answering.

Actually I'm coding an extension for inkscape that generates PDF in CMYK from SVG. And the only trouble is that: CMYKA. I'm able to use TIFF with JPEG compression in CMYK, or even JPEG format. But no success in TIFF with alpha layer.

I supposed ReportLab and PIL doesn't have plans to put this feature soon. So, is there a way to make ReporLab apply a bitmap mask on a "flat" bitmap?

Thanks for the attention.

Posted by igor on 27-08-2010 22:21

ReportLab image support is really primitive. The package doesn't support even CMYK images. We have patched internal ReportLab copy for that. But CMYKA images is more complex task. Such image can be embedded into PDF as a TIFF file only. Inside sK1 model there is no problem to support this image type, but we should provide CMYKA TIFF reading and writing using libtiff library. To resolve this issue we need implementing Python binding to libtiff. So it's not a simple task. But we are going to resolve it in nearest iterations because it linked with CDR files importing.

For your extension the best way is using UniConvertor with planned option --colorspace=CMYK. That is you pass regular SVG to UniConvertor and our application will convert it into CMYK based PDF. But your extension should rasterize all special effects (blur etc.).

Posted by jonata on 30-08-2010 11:50

I'm already able to save PDF in CMYK colors with the stable version of uniconvertor. The only issue is the transparent bitmaps... anyway iunivonvertor already does the job converting vectors in CMYK and including CMYK bitmaps too - that is great!

I'll be waiting anxiously Uniconvertor better handle CMYKA bitmaps.

Thanks for the attention