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Is this a small bug with transparent PNGs?

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I've been singing the praise of this app for a long time.


I tried making some transparent PNGs to be imported into Adobe Acrobat to use as signatures for our staff (Covid19 and all, working from home, etc etc)

When I import a transparent JPG, made by Paint.NET it works fine.



When I import a transparent PNG made by Paint.NET I get this




Normally I'd point my finger, straight at Adobe, not Paint.NET - but some other crappy dos based package my boss found has worked flawlessly at creating a transparent PNG.



"c:\Program Files\ImageMagick-7.0.10-Q16\magick.exe" c:\Data\sig1\paint.net-transparent-jpg.jpg -fuzz 10 -transparent white c:\Data\sig2\image-magick-transparent.png

(Converts a JPG, into a transparent PNG and the resulting PNG, works fine in Acrobat)


So what's the deal, is Adobe requiring a malformed PNG which ImageMagick complies with some weirdo bug or is Paint.NET not quite forming a perfect transparent PNG? (again, traditionally, I'd defer to Paint.NET always bein correct)

All 3 files attached for your own testing.


(I can produce the 3 files if it will help)






Edited by hamwizard
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24 minutes ago, hamwizard said:

When I import a transparent JPG, made by Paint.NET it works fine.


Transparent JPGs don't exist.


24 minutes ago, hamwizard said:

(Converts a JPG, into a transparent PNG and the resulting PNG, works fine in Acrobat)


You can't convert a JPG to transparent PNG, because transparent JPGs don't exist.

EDIT: oh, I see ImageMagick is converting white to transparent.


24 minutes ago, hamwizard said:

some other crappy dos based package


ImageMagick is not dos based. Yes, it is a command line program, but a Windows program.

And it is awesome; not crappy in the slightest.

Edited by toe_head2001
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(September 25th, 2023)  Sorry about any broken images in my posts. I am aware of the issue.

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On 4/27/2020 at 4:05 PM, BoltBait said:

Two things to consider when saving:




and after pressing Enter:






I'm a little annoyed by this reply but so be it, no big deal


I'm not completely stupid - did anyone here *actually try what I said*?

I'm definitely saving as PNG file.

I am saving in Auto-Detect mode

Yes you can see the transparency in the save as dialogue box.


The results are identical.

(yes, I screwed up discussing transparent JPG - ignore that at this point)


The resulting file, from Paint.NET, continues to be entirely incompatible with Adobe Acrobat.

So can someone else recreate / test?

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3 minutes ago, hamwizard said:

I'm a little annoyed by this reply


Sorry, but we get all levels of users around here. We never know what someone's skill level with Paint.NET is. So, I try to break things down to their most basic elements.


It looks to me that Adobe Acrobat is loading the PNG the same way it would load a JPG--that is, it is ignoring the transparency of the native PNG format and trying to make white pixels transparent.  I don't have Acrobat, so I would suggest seeing if there is an import setting in Acrobat that controls this.  Something like "key color: white" or something like that.


One way to test this would be to create a black signature on a white background and save it in PNG format, then see if that works in Acrobat.


When saving a PNG file, I believe Paint.NET converts all transparent pixels to transparent black which tells me that Acrobat is ignoring the transparency information in the PNG file and trying to read the color white as transparency. 

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Well I appreciate the responses - I was saving the file correctly, re-created the issue on the test PC.


However, you're right, it seems Adobe Acrobat will try to strip out the white on a transparent JPG and make a total mess of it all.

I then made a non transparent, black on white signature and it worked a treat.


Problem with that is, our solution requires a single file for users, for both MS Word and Adobe, not that this is the fault of Paint.NET - so we may need to continue with the current solution of ImageMagik or perhaps I could add a single, white pixel to a transparent signature, giving Adobe /something/ to strip out, so it doesn't ruin the rest of the PNG.

Either way solution found - thanks so much guys.


Sorry  I didn't test deeper, been very busy with more work coming in with Corona virus. 

Good luck.




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