Improve colorspace/color profile/gamma/OETF handling (was: Linear RGB data type)

Currently Vuo does not understand the difference between RGB that is in linear - or has an OETF (gamma) applied.

Attached is an example composition that shows the difference between the two- when using a blur.

I suggest that there be a linear data cable type, which can be converted easily. No image processing (compositing, blur, etc) should happen to the data when their is an OETF on the data.

This would mean that Vuo would need to read the ICC profile of the image, and remove the EOTF based on the tags. (And also allow the user to convert from known colour spaces - sRGB, P3, rec.2020 etc) https://nick-shaw.github.io/cinematiccolor/common-rgb-color-spaces.html

This is clearly shown in a blur effect, with an image with saturated colours.

Simply because x^2 + x^2 != (x+x)^2

Here are two screenshots from the attached Vuo composition, note that in both the blur effect is identical, the only difference is the top one has: OETF removed -> Blur -> OETF applied.

NOTE: for the attached example composition- I am using the approximation of pow(src, 2.2) for sRGB OETF

Component: 

Notes from Team Vuo

Vuo Pro: 

No — available with both Vuo CE and Vuo Pro

Complexity: 

●●○○ — A few weeks of work

Potential: 

●○○ — Appeals to current community

Currently, Vuo's colors and textures use the sRGB colorspace. Our overall goal for Vuo is to make it easy for people to get professional results, without having to master underlying technical details. So, we'd like to approach this a bit differently.

Our plan would be to audit Vuo's image filter nodes and figure out which ones handle colorspace properly as-is, and which ones don't (presumably blur is one that doesn't), and fix the ones that don't (i.e., make them convert input textures from sRGB to linear (when necessary), perform the filter, then convert linear back to sRGB (when necessary)). We think ideally this should all happen automatically so composition authors don't need to worry about it. Part of the fix would be to add an "Apply ICC Profile" node, to facilitate advanced color management.

Apply image filter protocols to movies (rotoscoping)

Implement "Image Filter" protocol for movies and "Filtered Movie" export option. Would pass the audio track through unchanged.
For the Community Edition, the same 1280x1280 image-size restriction as the current movie export feature would apply.

Component: 

Notes from Team Vuo

Vuo Pro: 

No — available with both Vuo CE and Vuo Pro

Complexity: 

●○○○ — Up to a few days of work

Potential: 

●●○ — Could expand community

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