Free Plug-in: Atlas for After Effects

#1

Atlas is a quick port of the open-source PFStmo tone mapping operators to the Adobe After Effects plug-in format. Atlas is free software licensed under the GPL.

I have just released the first version 0.1 so it might be buggy and probably not fit for production, but it’s open-source so I hope to get some help to bring it up to speed.


The right side was tone-mapped - note how the otherwise hidden detail becomes visible!

What’s tone mapping you ask? According to Wikipedia:

Tone mapping is a technique used in image processing and computer graphics to map a set of colours to another; often to approximate the appearance of high dynamic range images in media with a more limited dynamic range.
The technique is particularly useful if you have HDR images, such as rendered CG-imagery (OpenEXR!) in floating point color-depth, and you want to bring that broad spectrum into a range more suitable for display on a computer monitor or television screen. There exist numerous tone mapping operators that approach this problem from different angles and achieve varying results.

Currently Atlas supports the Drago, Ashikhmin, Reinhard, Mantiuk, Durand, Pattanaik and Fattal tone mapping operators.
Please note that for obvious reasons the effect is most useful in 32-bit color mode with 32-bit source images. It will work in lower modes but the resulting effect might not be what you expect.


Tone mapped photo of flowers

Lately, the effect has also become something of a fad in photographer’s circles, as a quick Flickr Search will show.

Please go ahead and download the free plug-in (including source code!) and let me know what you think!

#2

Quick heads-up: I fixed two nasty bugs thanks to user feedback. Please re-download Atlas if you’ve installed it previously.

Thanks!

#3

Hi, what’s the difference between this and using the built-in Exposure effect?

Also, having looked at the results produced by the different algorithms, are they in any way superior to reining in the highlights with Exposure and just using color correction?

Thanks for your input.

#4

Both may be used towards the same goal, but the results are quite different.

Technically, the Exposure tool is just a multiply operation that makes an image darker or brighter. So you either make everything darker/brighter or nothing. If you have an image with much contrast you will end up either blowing in out or making it pitch black in some areas, which is both not desirable.

Tone mapping on the other hand uses (in some cases very!) complicated algorithms that try to adapt an image to for example the human image field or perhaps that of a photographic camera.
So they automatically brighten the dark areas and vice versa in order to produce an overall well-balanced image.

Do a Flickr or Google Images Search for “hdr photo” and you should see examples of the very particular look that can be achieved with these tools. Of course, it is also well suited for regular, everyday production shots.

#5

Just fixed a bug in the color-space conversion process… the colors should look as expected now!

#6

I should have been clearer in my earlier post, I apologize.

What I mean is using Exposure to bring the highlights within the acceptable range of your output device and then using Curves or Levels or whatever to adjust the brightness and contrast of the overall image.

Since it’s a 32bpc project and Exposure, Curves and Levels are all 32-bit capable, stacking these effects would not clip the original data anywhere along the pipe, giving you full control over the dynamic range of the image.

In this regard, how is this inferior to the algorithms your plugin provides?

#7

No need to apologize, you ask a legitimate question.

It very much depends on the image at hand and the look you are aiming for. The native tools are not necessarily “inferior”, but the provided tone mapping operators take a lot of guess-work out of the equation by providing a set of automated solutions with very little room for error or adjustment.

One big difference is that the native tools all work on a global level, meaning each pixel is affected by the same amount by each operation, no matter what surrounding pixels look like. Some of the more complex tone mapping operators however are spatially varying, so over-bright pixels in one place may affect pixels in the surrounding area.
This is similar to the way the human eye works and can yield more realistic results than what the native tools are capable of. Of course it is also responsible for an ugly “halo” effect, so it’s a double-edged sword for sure…

Please read the Wikipedia article on tone mapping if you are interested in the details, they give a good explanation and overview. (I’m not that familiar with the algorithms myself, I just provide the “wrapper” that lets them run in After Effects :wink: )

#8

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