Transparent Objects Saved as Opaque in PDF

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When saving graphics as a PDF from either Igor 7 or 8, transparent objects are converted to opaque.  

Saving a PDF generates Graph1.pdf (attached) and it is clearly made of only opaque objects.

SavePICT/E=-8/EF=2

Instead, saving a PNG of the same graph (with the Transparency box checked), gives Graph1.png (attached).

SavePICT/E=-5/TRAN=1/B=576

Am I doing something wrong, or are transparent objects somehow not supported in PDFs exported from Igor?  

 

The complete code to make the graph:

Make/D Sine,Cosine
Sine = sin(2*pi*x/64)
Cosine = cos(2*pi*x/64)
Display Cosine,Sine
SetAxis/A
ModifyGraph mode(Sine)=7,usePlusRGB(Sine)=1,plusRGB(Sine)=(65535,0,0,32768)
ModifyGraph hbFill(Sine)=2
ModifyGraph mode=7,usePlusRGB=1,useNegRGB(Cosine)=1,rgb(Cosine)=(1,16019,65535),plusRGB(Cosine)=(1,16019,65535,32768),negRGB(Cosine)=(1,16019,65535)
ModifyGraph hbFill=2
ModifyGraph hbFill(Cosine)=1
ModifyGraph hbFill=2
ShowTools/A arrow
SetDrawEnv linefgc= (1,52428,52428),fillfgc= (2,39321,1,32768),linethick= 2.00

 

 PNG showing transparent objects. (343.44 KB) Graph1.pdf (7.62 KB)

Using Igor 8 with SavePICT/E=-2 I get a quartz PDF with transparency maintained.

March 4, 2019 at 08:15 am - Permalink

Igor PDF (SavePict/E=-8) does not support transparency. This is documented in the table that is part of the following help topic:

DisplayHelpTopic "Exporting Graphics (Windows)"

If you are using Macintosh, you can export as Quartz PDF (/E=-2) which does support transparency. Otherwise I can think of the following options:

1. Export using a format that does support transparency. That includes PNG, SVG, and I believe EMF.

2. It is possible that if you use File->Print and "print" to a PDF file, transparency will be preserved.

March 4, 2019 at 08:18 am - Permalink

Thanks for the quick reply!  I have to admit, I feel a little foolish.  I was looking at the SavePICT command help which doesn't mention the issue - it might be worthwhile to a note to that help file.  

There are many cool new features in Igor 7 and 8, and one of them is support for transparency in colors.  I find it disappointing and somewhat perplexing that transparency is not supported in PDF exports on Windows, and I am left with the lingering question, "Why?"  Something to add to the wishlist I guess...

For those who might be curious, my workaround is to export graphics from Igor in all their transparent glory as SVG, then convert them to a PDF in Inkscape, a free software that does support transparency in PDF exports on Windows.  The result is attached.  

 
Graph1 converted to a transparent PDF in Inkscape. (14.04 KB)

March 4, 2019 at 11:07 am - Permalink

gusdemann wrote:

I find it disappointing and somewhat perplexing that transparency is not supported in PDF exports on Windows, and I am left with the lingering question, "Why?"  Something to add to the wishlist I guess...

Dare I say that, AFAIK, this may be because PDF is akin to an afterthought option on Windows versus being an in-built option on macOS.

March 5, 2019 at 10:35 am - Permalink

And with Macintosh support, we didn't really feal a lot of point in putting a lot of effort into our own PDF generation. Even on Windows these days you can Print to PDF. I don't know what it would take to access the PDF Printer programmatically.

March 5, 2019 at 04:46 pm - Permalink