Use of PNGs in After Effects

[Jeremy Richard]

Hello everyone.

Here are some thoughts regarding After Effects and PNGs which might be of interest to anyone using both.

In one of a series of interesting articles regarding performance in After Effects, the author Chris Zwar argues that PNGS are not recommended when compositing in After Effects, especially as video resolutions get bigger.

Here are some quotes from his article After Effects & Performance. Part 14: Make it faster for free:

PNG files are so slow that I even checked in with Adobe to see if it’s a bug. It’s probably not. It’s just how they are, and it caused by the compression algorithm they use.

By the time we get to 8K resolution, a PNG file takes about 20x longer to save than a JPG or TIFF file. In the project I was using to test the rendering speeds of different file formats, rendering to a JPG sequence took AE about 2 mins 20 secs (140 seconds). Rendering exactly the same thing to a PNG sequence took over 40 minutes.

He recommends using either TIFFs or, more preferably, EXR files (Using EXRs and DWA in After Effects).

[Peter Wassink]

Would be great if TVPaint could support EXR files...
not sure if that is possible, TVPaint being 8 bit.
BTW this is not really Off topic, it might be a feature request.

[Dean]

This is some really useful information, I'll talk to the devs about this for sure.

[slowtiger]

Yes, PNGs always have been noticeably slower. This is also true for Quicktime video wit PNG codec.

[Jeremy Richard]

not sure if that is possible, TVPaint being 8 bit.

Indeed, it might not. On the OpenEXR website, it doesn't expressively mention 8bit:

Support for 16-bit floating-point, 32-bit floating-point, and 32-bit integer pixels.

One of the possible practicalities of EXR has been mentioned here previously, https://tvpaint.com/forum/viewtopic.php?t=7118.

Regarding PNGs, the fact that PNGs are slow to be processed is also experienced in Fusion:
https://www.steakunderwater.com/wesuckl ... 127#p41127

Targa files (.tga) are suggested as a replacement to PNGs, and it looks like it is suitable for animation:

This type of compression performs poorly for typical photographic images, but works acceptably well for simpler images, such as icons, cartoons and line drawings. (Wikipedia)

Another option could be to export as a .mov using the ProRes codec, which After Effects seems to process faster (from personal experience). But this option implies to re-export the whole sequence even if only a few frames need to be modified.

[Hironori Takagi]

This is the reason why targa(.tga) has been the standard in Japanese animation production for nearly 20 years.
Experience has shown that png takes a long time to encode and decode, causing slowness in Adobe applications.

[Xavier]

What about WebP ?

[slowtiger]

What about WebP ?

Uhg, please not.
I don't like to use anything outside the really old and trusted formats, not before I can afford completely new hardware. I'm stuck with old versions of everything (including myself), abandoning any old format will break my workflow completely. (Apple already did that with abandoning PICT, it's not even possible to open it and convert to something else - but I have one piece of music software which uses it and nothing else.)

[Jeremy Richard]

What about WebP ?

It seems that, like PNGs, WebP was made more for single images for the web, as opposed to image sequences. That didn't stop PNGs to be, it seems, widely used for image sequences, so maybe it could be the same for the WebP format. I would imagine that it is not so much the fact that for the same quality WebP is smaller, but if it can handle aspect of frame size or colour depth that PNGs cannot, then maybe WebP could possibly be used as an alternative.

On WebP's Wikipedia page there is a mention of animated images:

Google has proposed using WebP for animated images as an alternative to the popular GIF format, citing the advantages of 24-bit color with transparency, combining frames with lossy and lossless compression in the same animation, and support for seeking to specific frames. Google reports a 64% reduction in file size for images converted from animated GIFs to lossy WebP, however with a very noticeable visual impact, both at default settings, and optimised settings. When converting using lossless WebP, a 19% reduction is achieved as reported by Google, although real world performance is nearer to 10%

Here is someone doing lots of test with WebP images: Is there any benefit to using WebP images on my website?

There is a plugin for Photoshop, to export WebP files. I couldn't find anything for After Effects or Fusion.

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Regarding recent video codecs, it seems that HEIF and AVIF were made partly with image sequences in mind. They seem to both support alpha channels: AVIF - alpha compression?, HEIF (High Efficiency Image File Format) Reader.

Here are talks of support for both formats in ffmpeg:

• Add .avif support (AV1 Image File Format)
• HEIF support

Here are some encoders/decoders:

• libavif
• libheif

Here are results of a comparison made between AVIF and WebP:

• AVIF provides a smaller sized image compared to WebP.
• WebP works on only 8-bit depth, whereas AVIF supports 8, 10, and 12-bit, which will accept a broader range of images to be compressed.
• WebP supports only 4:2:0 channel, whereas AVIF supports 4:2:0, 4:2:2, and 4:4:4 channels.
• The image quality produced by WebP is lower than AVIF and even JPEG.
• AVIF supports HDR, which produces high luminosity images.

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The JPEG2000 format, which supports alpha channels, could also maybe be another alternative.

There is a plugin for Photoshop, Premiere and After Effects here to export as JPEG 2000.

Nevertheless, according to Adobe, there are few disadvantages to that format which might restrict its implementation for a wider use:

• Many web browsers and photo-sharing websites don’t support the JPEG 2000 format. JPEG 2000 is rarely used outside of these niche areas.
• There’s no backward compatibility with the original JPEG format, so users need to be able to code in a different standard than what most images use.
• JPEG 2000 codecs use a significant amount of computer memory, which can lead to slow performance and compression times. The file type works best on computers with lots of RAM.

[Xavier]

What about WebP ?

It seems that, like PNGs, WebP was made more for single images for the web, as opposed to image sequences. That didn't stop PNGs to be, it seems, widely used for image sequences, so maybe it could be the same for the WebP format. I would imagine that it is not so much the fact that for the same quality WebP is smaller, but if it can handle aspect of frame size or colour depth that PNGs cannot, then maybe WebP could possibly be used as an alternative.

On WebP's Wikipedia page there is a mention of animated images:

Google has proposed using WebP for animated images as an alternative to the popular GIF format, citing the advantages of 24-bit color with transparency, combining frames with lossy and lossless compression in the same animation, and support for seeking to specific frames. Google reports a 64% reduction in file size for images converted from animated GIFs to lossy WebP, however with a very noticeable visual impact, both at default settings, and optimised settings. When converting using lossless WebP, a 19% reduction is achieved as reported by Google, although real world performance is nearer to 10%

Here is someone doing lots of test with WebP images: Is there any benefit to using WebP images on my website?

There is a plugin for Photoshop, to export WebP files. I couldn't find anything for After Effects or Fusion.

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Regarding recent video codecs, it seems that HEIF and AVIF were made partly with image sequences in mind. They seem to both support alpha channels: AVIF - alpha compression?, HEIF (High Efficiency Image File Format) Reader.

Here are talks of support for both formats in ffmpeg:

• Add .avif support (AV1 Image File Format)
• HEIF support

Here are some encoders/decoders:

• libavif
• libheif

Here are results of a comparison made between AVIF and WebP:

• AVIF provides a smaller sized image compared to WebP.
• WebP works on only 8-bit depth, whereas AVIF supports 8, 10, and 12-bit, which will accept a broader range of images to be compressed.
• WebP supports only 4:2:0 channel, whereas AVIF supports 4:2:0, 4:2:2, and 4:4:4 channels.
• The image quality produced by WebP is lower than AVIF and even JPEG.
• AVIF supports HDR, which produces high luminosity images.

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The JPEG2000 format, which supports alpha channels, could also maybe be another alternative.

There is a plugin for Photoshop, Premiere and After Effects here to export as JPEG 2000.

Nevertheless, according to Adobe, there are few disadvantages to that format which might restrict its implementation for a wider use:

• Many web browsers and photo-sharing websites don’t support the JPEG 2000 format. JPEG 2000 is rarely used outside of these niche areas.
• There’s no backward compatibility with the original JPEG format, so users need to be able to code in a different standard than what most images use.
• JPEG 2000 codecs use a significant amount of computer memory, which can lead to slow performance and compression times. The file type works best on computers with lots of RAM.

Wow, thanks for the explanation (and the time you spent writing it / comparing formats) !
I'm not very familiar with these new image formats. But I'm not a specialist of animation either.

In my opinion anything, which offers a better compatibility between your workflow tools, would be a plus for TVPaint.
Yet it's not that easy : we have to combine the new software components required to support AV1 and HEVC, with the old code of TVPaint.

[Xavier]

Note that After Effects supports HEIF but not AVIF : https://helpx.adobe.com/after-effects/k ... rmats.html

[Jeremy Richard]

The AVIF format seems interesting for at least four reasons:

• can be lossless and/or lossy
• better compression keeping same quality (compared to WEBP or JPEG for example)
• it's 8bit compatible, unlike EXR
• it's royalty free unlike HEIC

Nevertheless I can't find examples of this format being used in production; used as a lossless format.
A bit regarding broadcasting and Netflix having a go at using AVIF.

As of March 2023:

• there is mention of AV1 in the Supported Codec List of Blackmagic (although I personally couldn't import an AVIF in Fusion).
• Nuke doesn't mention it. Although there is a AVIF plugin apparently, but it doesn't look 'plug and play'.
• there is no mention of AV1/AVIF regarding After Effects, as Xavier stated

But, maybe, as for final exports from TVPaint (with no compositing or editing needed afterwards) it might still be interesting to consider AVIF for the future, as

• it's compatible with major web browsers, except with Edge
• and could be a replacement to GIF

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JPEG XL might be an interesting format for production:

• It's lossless
• supports layers and additional channels (like alpha channel)
• supports 8-bit
• it's royalty free.

According to the JPEG XL Use Cases and Requirements document, this file format has animated image applications and printing in mind (amongst other things like virtual reality)

Here is the JPEG XL reference implementation.

And here are comparisons with other formats.

[D.T. Nethery]

This is very useful information about the various image formats (also including your original post from last year). Thank you.

[Jeremy Richard]

Thank you.

Chris Zwar, who I quoted in the first post of this topic, came back on the subject in a video about the benchmark he did regarding png performances in After Effects.

[D.T. Nethery]

This is some really useful information, I'll talk to the devs about this for sure.

Hi, Dean ,

What was the outcome of your discussion with the developers about adding support for exporting to EXR files from TVPaint to After Effects ?