Animated GIF files from PNG with alpha

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Rick Montgomery
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Joined: Mon Jan 22, 2007 3:08 pm

Animated GIF files from PNG with alpha

Post by Rick Montgomery »

Thorsten,I'm having a weird problem with animated GIF files that use transparency. See http://thevams.net/rick/gifdemoThe animations on the top row were created as series of PNG files in POV-Ray. I used GraphicConverter to merge the PNG files into a GIF animation.The first animation on the top, disc-notrans.gif, was created by merging PNG files that had no alpha channel, and the animation loops repeatedly.The second animation on the top, disc-trans.gif, was created from PNG fils with an alpha channel. When I open it in Safari, Opera, or Google Chrome, it loops once (that is, it plays through twice) and then stops. In Firefox or SeaMonkey it doesn't loop at all - it plays through once and stops.The third animation on the top, disc-transremoved.gif, was created by opening disc-trans.gif in GraphicConverter and selecting "disable transparency in all frames." It loops correctly in all three browsers.On the bottom left is an animation that I created by merging four GIF files with no transparency. It loops as expected. To its right is the same GIF animation, edited to make white transparent. It also loops as expected. For the third animation on the bottom row, I created four PNG files within GC. I specified a delay of 0.5 seconds per frame in Convert & Modify, but for some reason the first frame has a delay of 0.1 second. This animation behaves exactly like the one made from externally-created PNG files with an alpha channel, looping once in Safari, Chrome, and Opera, and not looping at all in Firefox and SeaMonkey.I wonder, have you given any thought to supporting animated PNG (APNG) files? It is a superior format to GIF in that it supports an 8-bit alpha channel. Not all browsers support it, but those that do not should display the first frame of an APNG animation as a static PNG image (that's what Firefox and Opera on Mac do). The Mac versions of Safari and Chrome handle it correctly - I haven't tested on Windows.Wikipedia page for APNG: https://en.wikipedia.org/wiki/APNGThanks for all you do,Rick
thorstenlemke
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Joined: Fri Dec 30, 2016 12:00 pm

Re: Animated GIF files from PNG with alpha

Post by thorstenlemke »

Dear Rick,many thanks for your report.Did you use the current version 9.7.4?Can I please get the source files for testing to lemke@lemkesoft.de ?The upcoming version 10 will support APNG creation.Thorsten
Rick Montgomery
Posts: 0
Joined: Mon Jan 22, 2007 3:08 pm

Re: Animated GIF files from PNG with alpha

Post by Rick Montgomery »

Thorsten, I'm using App Store 8.8.2 (although I have purchased directly from LemkeSoft two or three times in the past). I see there is a GraphicConverter 9 available; maybe I'll give it a try. If it doesn't cure my problem, I'll post the source files and send you a link.
Rick Montgomery
Posts: 0
Joined: Mon Jan 22, 2007 3:08 pm

Re: Animated GIF files from PNG with alpha

Post by Rick Montgomery »

Happy to report that GraphicConverter 9 fixed my problem. I've added the actual animation that I was working on when I discovered the bug, and as you can see, it works perfectly.http://thevams.net/rick/gifdemo/
thorstenlemke
Posts: 0
Joined: Fri Dec 30, 2016 12:00 pm

Re: Animated GIF files from PNG with alpha

Post by thorstenlemke »

Dear Rick,many thanks for your update onto this.Thorsten Happy to report that GraphicConverter 9 fixed my problem. I've added the actual animation that I was working on when I discovered the bug, and as you can see, it works perfectly.http://thevams.net/rick/gifdemo/
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