Blend if by Saturation

[Ivan Zajats]

Add Blend if by Saturation! would save much time fixing over- and undersaturated areas.

[D Fosse]

There's no way that can work in the current Blend If model, which is based on absolute RGB numbers per channel.

Saturation is a relative characteristic, defined by the differences between the three channels, which is again relative to the color space used.

However, on current document level, a saturation map can have its uses, for instance as a base for masking, and this has been discussed on several occasions here in the forum. Personally I haven't had much need for it so I haven't bookmarked any of those discussions. I find it far more useful to focus on channel clipping than degrees of saturation, but that's just me.

Off the top of my head I would think a saturation map could be made by combining the a and b channels in Lab. But I haven't done any testing.

[Ivan Zajats]

@D Fosse, any pixel has a Saturation value, doesn't it? so, what's the problem to make a scale from 0 to 100 with 2 sliders?

[D Fosse]

Only valid within that document/color space. Saturation is not an absolute number.

I'm not saying it's not possible, but it would reqire rewriting the whole Blend If function, so then it's a cost/benefit ratio. If you get enough votes for this, maybe. Personally I wouldn't have much use for it, but again, as I say, that's just me.

[rayek.elfin]

This is actually quite handy to have under circumstances.

For example (taking a cue from the competition), PhotoLine allows the user to use 'Blend if" in HIS (Hue Intensity Saturation) mode, thus enabling this type of move.

Here is a quick example to show the difference between a typical blend if by saturation and blend if by gray. Notice that the blend if by gray move saturates the blue in the background and colour shifts other unwanted parts, which we want to avoid.

And the blend by saturation maintains and strengthens contrast in the dog's fur textures as well.

 

(note that PhotoLine allows for the Curves to work in HIS mode, which is also not possible in Photoshop unfortunately)

Obviously there are alternative methods to manage a similar move in Photoshop, yet this example does show how straightforward and simple this adjustment is.

So, yes, I agree with the OP that this would be a useful addition.

[Ivan Zajats]

where are your votes?)
I'd use this to fix skin (and thousands of other retouchers would)

[Lumigraphics]

Blend If is old and more likely to be removed or completely rewritten than to be changed in its current form.

[rayek.elfin]

@LumigraphicsWell, a lot of the core functionality of Photoshop is old...

So many base functions could benefit from a variety of improvements, but it seems that the Photoshop team is instead asked by management to work on implementing AI and cloud related stuff nowadays.

[Lumigraphics]

If you were a sales guy and had the choice of whether to improve a somewhat obscure, mundane feature or something sexy and buzzwordy like AI, which would you choose? Follow the money. Adobe is run by sales guys.

[Ivan Zajats]

@Lumigraphics, can't they improve both? I think AI programmers and "classic" programmers are completely different people/teams, aren't they? if so, each can easily do their own job 🙂 

[Lumigraphics]

The proof is in the doing, not the wanting.