What is "Photoshop's Compositing Engine"?

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Hi,

Just a question or three, which I have to ask, as I don't really understand the difference between Photoshop's old and the new (PS CC 2019) compositing engines, or even what it means.

I see many posts where people are told to check the Legacy Compositing under Performance because some users have issues with PS CC 2019. By doing this, their issues go away. 

Why?

What is so different between the old and new composite engine?

What is a compositing engine?  I'm curious. 

Hoping someone will answer my question as I don't really understand and I guess by knowing, it's another tool under my belt if I come across any problems myself. 

I've tried searching for an answer but can't seem to pinpoint a direct answer. I'm probably not composing the question right.

I looked in my Prefs/Perfomance and mine is unchecked.

Thanks in advance.

Rosa

 
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Rosa

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Posted 3 months ago

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Cristen Gillespie

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All I know is it's supposed to be a new "engine" so performance in several areas? will be faster?  Maybe Jeffrey will give us a better explanation.  It sounds as if it's something very deep under the hood and probably not one of those things that we really need to understand, but since the technology is new, they have given us a way back in case there's a problem. If we didn't know anything about the Legacy Compositing Engine, it's doubtful we need to know anything about the new Compositing Engine.<BG>

I'm running fine since the last update without using Legacy Compositing.
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Rosa

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I understand what you're saying Cristen :)

I'm a deep thinker and curious about what makes things tick, so it got me wondering what the Compositing Engine does which I think David  has answered my question.

By checking Legacy Compositing in PS CC 2019 it fixed issues for many users including me because of issues within PS - the new compositing engine.

Since 20.0.3 I've unchecked the Legacy Compositing and all seems fine for me so far.
My layers, all with blend modes, filters and adjustments all work how they should in the final image. Fingers crossed, nothing changes, but will be keeping an eye out on things. At least I know if something is not right with PS, the first thing I'll do is check Legacy Compositing first and work from there.

Thank you Cristen and David  for your responses. They are much appreciated.

Cheers.





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David Converse

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Compositing is taking all of your layers and adjustments and making a final display image. Adobe is developing a new engine (that does this compositing) presumably because Apple and Microsoft are both improving their display capabilities.
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Cristen Gillespie

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So we can take "compositing" literally the way we use it and have a good idea of what it's doing. The engine is for displaying what we take for granted (except when something goes wrong<G>. Thanks.
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David Converse

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Think of two layers. They both have specific pixel values. If I change the blend mode, the pixels on each layer don't change, but the final image does. That's because the compositing engine must make a final image given all parameters.

If you only have one layer, there is no composite, Photoshop just displays the pixel values. Even then they can still be affected by things like color profiles and mode.
(Edited)
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Cristen Gillespie

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And of course, however many layers, it will have to keep up with us in real time. I don't actually know the limit to layers now. But I know it's expanded over time, at the least once, to some rather incredible number, but I'm just as sure we enjoy not having to consider how many layers we're creating as having a bad effect on the ability to display? And maybe an unrelated question, but you know a lot about this—will this also help with keeping up with painting? Each stroke, even on the same layer has to be rendered in the display.

How are Apple and Microsoft updating their display capabilities? Is this Metal, that I keep hearing about? Or something else new and different? I know my iPad Pro is wicked fast in scrolling about.
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Rosa

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Thanks David  and Cristen, you've both been so helpful.

Information now stored in my brain. Haha!