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LAB color space equivalent in AE?

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jim bachalo
LAB color space equivalent in AE?
on Aug 11, 2011 at 1:53:45 pm

Hi
Can someone tell me if there is a LAB color space equivalent in AE? I'd like to try applying filter effects and curves to the luminance value of a layer, and not the colors.

Local is the new global


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Kevin Camp
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 3:18:24 pm

you can probably get similar results by duplicating the layer, setting the top duplicate's blending mode to 'color', then do the effects on the lower duplicate.

if you are working in 8-bpc, then you can do this with a single layer, using cc composite as the last effect and setting composite original to 'color'.

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW


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rona gales
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 4:49:12 pm

cc composite CS5 has a bug... Color blending and Luminosity blending are flipped

The God Of Color Of The Universe Will Rise Again!


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Darby Edelen
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 6:55:00 pm

[rona gales] " cc composite CS5 has a bug... Color blending and Luminosity blending are flipped"

Weird, I don't see this problem on my system.

Darby Edelen


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rona gales
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 4:36:59 pm

channel combiner1 set RGB to YUV
Effects
Channel combiner2 set YUV to RGB

Curves Effects
RGB= don't use
Red= lightness
Green=a
Blue=b

The God Of Color Of The Universe Will Rise Again!


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jim bachalo
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 5:36:34 pm

Thanks!
Now if only channel combiner were 16bit:(

HDR Compander I suppose if I'm using a 16 or 32bit workflow.

Haven't done a lot of testing with HDR Compander...for 8 bit effects in a 16-32bit project. What are the drawbacks?

Local is the new global


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rona gales
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 6:35:24 pm

With compression and uncompression you can lose some precision in values that you can't see 95% of the time.
Maybe you want to start another thread!

The God Of Color Of The Universe Will Rise Again!


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Darby Edelen
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 6:52:43 pm

[jim bachalo] "Haven't done a lot of testing with HDR Compander...for 8 bit effects in a 16-32bit project. What are the drawbacks?"

It is not a good option if you have a huge range of values. You have to use the Compander to compress ALL of the color information (that you want to keep) into an 8bpc range (0-1) and then expand that color information back out to its original range. This is problematic when you perform an operation in between the compression and the expansion that changes the bit depth.

So if you have values ranging from 0-50 the process of compressing those down to 0-1 is not inherently bad in 32bpc, but once you apply an 8bpc effect you have limited each color channel to only 256 unique values. When you expand that back out to 32bpc it will have superwhites, but it will show the worst banding you've ever seen in your life because it's taking only 256 unique values and expanding them out to cover a range of values 50 times as large as 0-1.

All of that said, it's a very valuable effect if you're dealing with smaller ranges of values (0-5) or you don't mind clipping the values at some superwhite level. Also it will be happier with 16bpc effects as you'll be limiting to 65536 unique values instead of 256.

Darby Edelen


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Darby Edelen
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 6:58:17 pm

[jim bachalo] "Now if only channel combiner were 16bit:("

Which is why I always use blend modes for this :) The Luminosity or Color mode is perfect for your purposes. You'll have access to the luminance and colors separately that way.

The only downside is that you don't have access to the color difference channels (you'd have to use the Channel Combiner to do that), but there are very few reasons I can think of that any non-super-human-techno-graphics-compositor would ever need access to color difference channels.

Darby Edelen


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rona gales
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 9:37:01 pm

You're probably not using HDR Compander the right way!
Also you're not understanding the need and use of LAB/YUV color mode properly.

The God Of Color Of The Universe Will Rise Again!


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Darby Edelen
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 10:43:10 pm

[rona gales] "You're probably not using HDR Compander the right way!
Also you're not understanding the need and use of LAB/YUV color mode properly."


Make a Ramp, then use Exposure +5 stops and 0.5 gamma, add your HDR Compander effects, wedge your round trip Channel Combiner between them and find your best settings (Gain 5, Gamma 2).

I guarantee your ramp is going to look terrible on the other end of the HDR Compander effects with an 8bpc effect wedged between them.

Thanks for trying to fix my workflow though.

As for the need and use of Lab and YUV, in the original poster's case they are entirely unnecessary. There is no need nor use for them in his scenario as he's described it.

If you like to use curves to adjust the color difference components in YUV that's fine, but that's not what the original poster asked about and it's not the ideal usage for what he wants to do.

If you're disagreeing with something specific I said, please do tell me why you disagree.

Darby Edelen


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rona gales
Re: LAB color space equivalent in AE?
on Aug 11, 2011 at 11:22:32 pm

I will suggest you to contact Adobe with your ramp problem.

<>

Do you not read "filter effects"? Luminance blending mode is not the same as Y in YUV

The God Of Color Of The Universe Will Rise Again!


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Darby Edelen
Re: LAB color space equivalent in AE?
on Aug 12, 2011 at 12:06:51 am

[rona gales] " I will suggest you to contact Adobe with your ramp problem.

<>

Do you not read "filter effects"? Luminance blending mode is not the same as Y in YUV"


I did not intend to present the Ramp example as a problem I was having. I was suggesting that you try it, so that you could see that the HDR Compander effect is not a viable solution in some cases.

Thanks for the suggestion, but Adobe is already aware of the limitations in HDR Compander.

Is "filter effects" a blog? I have not read it, but I stand by my recommendation of the Luminance blend mode for the original poster's purpose. I can think of a couple reasons why it would be preferable over using Channel Combiner:

-It's 8bpc.
-To access only the Y component an effect has to be able to operate on channels individually.

Darby Edelen


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rona gales
Re: LAB color space equivalent in AE?
on Aug 12, 2011 at 12:20:39 am

I don't have the "ramp problem" on my system!! Good luck to you and Adobe

Adjusting Curves effect in YUV is not the same as adjusting Curves effect with luminance blending mode. The weight of the color in YUV is different and you get softer whites and a lot better color reproduction.

The God Of Color Of The Universe Will Rise Again!


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Darby Edelen
Re: LAB color space equivalent in AE?
on Aug 12, 2011 at 1:48:50 am

[rona gales] "Adjusting Curves effect in YUV is not the same as adjusting Curves effect with luminance blending mode. The weight of the color in YUV is different and you get softer whites and a lot better color reproduction."

Yeah, you do get different results when using color correction effects. Especially the saturation of the colors.

If the original poster is used to making channel color adjustments in Lab then YUV may be a better model to follow as it behaves more like Lab. I should have recognized that in the original post.

I usually prefer to adjust the luminance of the image without affecting the color at all, and then adjust the color if I need to, but that comes down to a personal choice. We'll agree to disagree.

Darby Edelen


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rona gales
Re: LAB color space equivalent in AE?
on Aug 12, 2011 at 2:29:13 am

With "Luminance blending mode" you are affecting the color slightly and not with Y/ L

If you adjust the Y curve only with:
CC composite RGB to YUV
Y=R curve only
CC composite YUV to RGB
You will get softer highlights and better color reproduction.

If you adjust RGB curve only with:
RGB curve only (not the R curve, G curve and the B curve )
Luminosity blending mode
You will get harsher highlights, slight lost of saturation and sometime a slight hue change too. You should do some test with skin tone for example....

The God Of Color Of The Universe Will Rise Again!


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Jim Arco
Re: LAB color space equivalent in AE?
on Aug 12, 2011 at 12:15:30 pm

Jim,

I haven't found a way to work with Lab color space inside of After Effects. However, you can open your video in Photoshop, convert to Lab, and apply filters. After you save the PSD, you can import it to AE and the filtering done in Photoshop remains intact. (No need to change back to rgb.)

This works great for those times you need to make broad changes to luminance or to color. Also, little surface blur applied to the a and b channels can be used to get rid of some types of noise. If you modify the Photoshop file, you need to right-click on the footage and reload it in AE.


Jim


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rona gales
Re: LAB color space equivalent in AE?
on Aug 12, 2011 at 1:47:36 pm

YUV is not exactly the same as LAB but Y/L it is very close....

You are converting back to RGB and "merging the layers" automatically with After Effects when you import the PSD files if the color mode is not RGB....even if command E get you back to LAB mode in Photoshop.

Yes we all do round trip to Photoshop too but keep in mind that some effects and plugins don't carry over After Effects. Then it's render time:)

The God Of Color Of The Universe Will Rise Again!


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rona gales
Re: LAB color space equivalent in AE?
on Aug 12, 2011 at 2:28:31 pm

Also you may find it hard to go back to the original PSD after you've made changes in AE. The AE changes don't carry over to PS... You may end up going back and forth and second guessing the new changes....

And you need to RE-save the PSD file before you can reload the footage in AE.

The God Of Color Of The Universe Will Rise Again!


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