RetouchPRO

Go Back   RetouchPRO > Technique > Photo Compositing
Register Blogs FAQ Site Nav Search Today's Posts Mark Forums Read


Photo Compositing Collage, montage, masking, selections, combining, etc.

Applying masks to individual RGB channels

Reply
 
Thread Tools
  #1  
Old 07-08-2015, 01:54 PM
FinderBinder FinderBinder is offline
Junior Member
 
Join Date: Jul 2015
Location: Up, Up and Away
Posts: 8
Question Applying masks to individual RGB channels

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?
Reply With Quote top
  #2  
Old 07-08-2015, 02:00 PM
FinderBinder FinderBinder is offline
Junior Member
 
Join Date: Jul 2015
Location: Up, Up and Away
Posts: 8
Question 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?
Reply With Quote top
  #3  
Old 07-08-2015, 03:07 PM
klev klev is offline
Senior Member
 
Join Date: Jun 2010
Posts: 1,109
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.
Reply With Quote top
  #4  
Old 07-08-2015, 03:14 PM
FinderBinder FinderBinder is offline
Junior Member
 
Join Date: Jul 2015
Location: Up, Up and Away
Posts: 8
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.
Reply With Quote top
  #5  
Old 07-08-2015, 05:59 PM
klev klev is offline
Senior Member
 
Join Date: Jun 2010
Posts: 1,109
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.
Reply With Quote top
  #6  
Old 07-08-2015, 09:55 PM
FinderBinder FinderBinder is offline
Junior Member
 
Join Date: Jul 2015
Location: Up, Up and Away
Posts: 8
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

.
Attached Images
File Type: jpg Forum-example.jpg (79.7 KB, 33 views)
Reply With Quote top
  #7  
Old 07-08-2015, 10:16 PM
Tulack Tulack is offline
Senior Member
 
Join Date: May 2015
Posts: 191
Re: Applying masks to individual RGB channels

Quote:
Originally Posted by FinderBinder View Post
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.
Reply With Quote top
  #8  
Old 07-10-2015, 11:39 AM
FinderBinder FinderBinder is offline
Junior Member
 
Join Date: Jul 2015
Location: Up, Up and Away
Posts: 8
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.
Reply With Quote top
  #9  
Old 07-10-2015, 12:53 PM
klev klev is offline
Senior Member
 
Join Date: Jun 2010
Posts: 1,109
Re: Applying masks to individual RGB channels

Quote:
Originally Posted by FinderBinder View Post
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.
Reply With Quote top
  #10  
Old 07-11-2015, 04:46 PM
John Wheeler's Avatar
John Wheeler John Wheeler is offline
Senior Member
 
Join Date: May 2011
Location: Colorado
Posts: 583
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:
Attached Images
File Type: jpg JKW-Channel-specific-masks-1.jpg (66.6 KB, 15 views)
Reply With Quote top
Reply

  RetouchPRO > Technique > Photo Compositing


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is Off
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
RGB colour Retouching??? EV0BEE Photo Retouching 7 01-14-2014 10:16 AM
rgb cmyk channels kyleb Photo Compositing 8 09-10-2013 06:19 AM
work in rgb save lab or cymk mask,how can i do it? mantra Photo Retouching 8 12-28-2011 06:40 PM
RGB to Lab/CMYK and back to RGB D Thompson Photo Retouching 44 08-13-2011 09:52 AM
TIP: luminosity mask for individual RGB channels thomasgeorge Photo Compositing 2 08-22-2001 03:08 PM


All times are GMT -6. The time now is 06:39 PM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
SEO by vBSEO ©2011, Crawlability, Inc.
Copyright © 2016 Doug Nelson. All Rights Reserved