Applying masks to individual RGB channels

[FinderBinder]

Hey All,

In RGB mode, is it possible to apply a layer mask to a component channel in a layer, instead of affecting all three channels (RGB) at once? I'm guessing no, since every layer has only one alpha channel for transparency (A). But what about a simulation?

To approach it another way, is it possible to split a layer into 'pseudo-channel' layers, alter the transparency of one or more of the layers, then reassemble them without winding up with something 3X as opaque?

I'm hoping to provide a single layer to my client Thoughts?

[FinderBinder]

Re: Applying masks to individual RGB channels

To clarify, I tried splitting a layer into its channels by making three duplicate layers, each with a different channel (R, G or B) checked in the Advanced Blending options. I applied different masks to each 'pseudo-channel' layer. The stack looked as I hoped when floating over a background. But a re-merged layer made from the split layers looks too solid (I'm guessing it's 3X as opaque as it seemed as separate layers.) No good.

I also tried knocking out the target layer with three masked Solid Color Fill layers, with each set to a different visible channel in the Advanced Blending options. This arrangement also worked. But when I merged the group the knockout effect goes away, leaving it fully opaque (and darker). Nope.

I'd like to know how to provide the same appearance from a single layer floating over a background as the split layers looked over that background.

(I've explored Merge Channels, too, but it only seems to work with flattened greyscale images, so no transparency.)

Any other options?

[klev]

Re: Applying masks to individual RGB channels

First it's important to mention that if you can't flatten it without problems, you don't have an image. You can't do anything with it if outside of photoshop if you can't flatten it without undesirable effects. Don't hand a mess off to someone else.

Anyway this is done semi-frequently in other applications, which have better interfaces for this sort of thing. In normal mode these things are additive as you have seen. You can avoid some (well most) problems by using layer->create clipping mask to nest these things. Other than that I would want to see an example.

Lastly are you sure you're not making this into more work than necessary? Many adjustments can be directly targeted by channel, such as curves or layer groups (uncheck channels in blending options as necessary). Merge channels won't help you, and I'm not entirely sure how you're going about this. You don't provide a very good description. If you're able to post something demonstrating the problem, even if it isn't the actual image, I can take a look at it. I may be able to determine what you're doing wrong.

Reading that back my post isn't very clear either, but I'm out of time. If you post something, I can probably tell you how to fix it. Make sure it's structured identically. Replace any sensitive data with garbage data.

[FinderBinder]

Re: Applying masks to individual RGB channels

Thank you. It seems a demo file might describe the situation better than all these words.

I'll post a link as soon as possible.

[klev]

Re: Applying masks to individual RGB channels

I re-read it and I may have figured out your mistake. You used merge over something that looked appropriate against a background layer. If it looked as expected, flatten should have done the trick. You probably just merged your new layers first. If you want to be able to click the adjustments on and off, duplicate the background layer, turn off visibility on the original background layer (background copy still visible), then hit merge visible.

[FinderBinder]

Re: Applying masks to individual RGB channels

I should've stated the single-layer result is meant for the client to use over any background. I’m hoping there’s a way to create the same effect in one layer as when when channels are individually masked.

The attached image shows the intended effect. The grey rectangle has one letter shape knocked out per channel. But when that split-layer stack is merged, the transparent areas go solid.

Like I said, I think this might not be technically possible, but maybe the community knows better.

PSD file here

.

[Tulack]

Re: Applying masks to individual RGB channels

I should've stated the single-layer result is meant for the client to use over any background. I’m hoping there’s a way to create the same effect in one layer as when when channels are individually masked.

The attached image shows the intended effect. The grey rectangle has one letter shape knocked out per channel. But when that split-layer stack is merged, the transparent areas go solid.

Like I said, I think this might not be technically possible, but maybe the community knows better.

PSD file here

.

Because you are merging down. And if you are using "blend if" that is what going to happened. When "blend if" in use and you merging down, you creating layer with visible parts without any blending.You should use "merge layers" ctrl+shift+E. Or flatten image.

[FinderBinder]

Re: Applying masks to individual RGB channels

Thanks for your attention, everyone. Tulack, did you try your suggestion with the PSD file?

I'm gonna resign to thinking there's no way of getting around this with one layer in the way I hoped. I'll ask the client about applying the graphic myself.

[klev]

Re: Applying masks to individual RGB channels

I'm gonna resign to thinking there's no way of getting around this with one layer in the way I hoped. I'll ask the client about applying the graphic myself.

I messed with it. If you want it to go over any background, keep it in one group, not one layer. It might be possible, but you have overlapping portions, which means there is no easy way to go about it. Some applications do allow for separate alphas to be connected to red, green, and blue. Photoshop isn't one of them. If you were making something for say nuke in photoshop, you would just export them. You're aren't doing so, so you would have to approach this in a totally different way. As I mentioned you can send your client the psd with the layer group, assuming the two of you are using compatible versions of photoshsop.

[John Wheeler]

Re: Applying masks to individual RGB channels

I have not found a way to do it either after thinking/working on it a while.

Closet I came was a single Layer overlay with an applied blend yielding:

[John Wheeler]

Re: Applying masks to individual RGB channels

Put a little more work into it and came up with a two Layer (not 1 Layer solution). This solution requires no Layer Masks, the only Artwork transparency is for the border, no special Layer Style mode used, and you can slide any background under these two Layers and get the correct result.

I can give more details of its creation if this is of interest to the OP.

- The bottom Layer is the background
- The middle Layer is the solid color set to the same color as the color channel mask. Overlapping colors just add. This Layer acts as a color filter to only send the correct colors up the Layer stack from the background. This Layer is set to Multiply
- The upper Layer is the Gray gradient where each color channel mask zeros out that particular color in that image. Overlapping areas zeros out two of the colors. This Layer is set to Linear Dodge (Add).

First image is the entire stack with the Layers Panel
Next image is the Composite image which matches the OPs image
Next image is the top Layer in isolation
Next image is the middle Layer
Next image is the background Layer

Hope this is of some interest.
John Wheeler

Composite-wtih-Layer-Stack-All-Layers-Screen-Shot-2015-07-12-at-12.15.46-AM-copy.jpg

Top-Layer-Linear-Add-Blend-Channel-specific-masks.jpg

Color-Masking-Multiply-Blend-Channel-specific-masks.jpg

Background-Image-Channel-specific-masks.jpg

[FinderBinder]

Re: Applying masks to individual RGB channels

Stepped away and thought the thread went dormant.

John, that's a fascinating workaround! I didn't consider that or stumble upon it at all. Thanks for your attention.

[John Wheeler]

Re: Applying masks to individual RGB channels

Stepped away and thought the thread went dormant.

John, that's a fascinating workaround! I didn't consider that or stumble upon it at all. Thanks for your attention.

You're welcome FinderBinder