Re: PPW alternate versions - how to compare them


Thomas Hurd,MD
 

I like all the ways Doug described. Once you have used photoshop for a while, making this extra channels and files becomes second nature.

 Another way to try the changes to the red channel “risk free” inside the source doc:
Select the red channel so only it is visible
Right click duplicate channel default name “red copy” (You can name it anything  you like at this point or later).
This is now an alpha channel and can be manipulated without affecting your tri-channel image.
With the duplicate channel selected, you can use apply image to replace or blend with any other channel in that document (or another of equal dimensions.)
With the red channel copy, now modified initially with a blend, you can then use command-M curves, or any other image adjustment directly on the duplicate. Although technically it does not use reversible adjustment layers to modify it, you can use command Z to reverse, or go through history.
Another maneuver that Dan has demonstrated a few times in the past 11 weeks:
You can
1. blend the channel with different modes, overlay being particularly interesting with a and b channels from LAB
2. Immediately after pressing OK you can use Fade to cut back the effect, and/or again change blend modes.
3. You can also use drawing tools on the alpha channel, such as brush tool in grayscale, or dodge and burn, gradient, etc. and again, immediate after the tool maneuver you can use Fade.

Anytime you want to use the newly modified red channel as part of you image, switch back to Doug’s description, and use apply image to test out your new red channel. Then comman-Z, etc.

Warning: channel blending and other Channel operations can be very addicting.

Tom Hurd

On Aug 10, 2020, at 1:05 PM, k_d@... wrote:

"analyze the difference between an original red channel and a copy of that channel with the blue channel applied to it"

Select red channel, use apply image with blue channel,
BUT, before you close/accept, click preview on/off to your hearts content.

For a fixed view: copy red channel to new .psd doc, make a new red channel with blue applied and save as a layer over the red channel.psd,
then turn red/blue channel on/off;
or make the top layer as difference mode and observe: black means no difference, anything else shows the difference.
You can do this same thing in the .psd source but a separate.psd doc means you can save/test/adjust/export etc. and not risk messing up the source doc. and keep thinking separated between the 2 .psd files.

Doug Schafer

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