Blend mode "Clear" -> Why doesn't exist for layer ?

@D Fosse 

Another example (more explicit, I think)

Here's my work:
- 3 layers, ALL filled with pixels over the entire image.

- I activate the advanced blending parameters shown by @davescm  (equivalent to the "Clear" blend mode).

Miracle ! The "Blue" layer is NOT ENTIRELY erased by "Calque_1" (layer_1), even though the latter is in "Clear" merge mode. It is POSSIBLE to assign a "Clear" blend mode, WITHOUT erasing EVERYTHING!

Why ?
Simply because there is TRANSPARENCY on "Calque_1" (layer_1) 😊👍
"Calque_1" (layer_1) does NOT erase the entire layer below it ! Quite the contrary !

And that's one of the great strengths of Photoshop, which I use every day!

You can play around with transparency in a subtle, fine-tuned way!
Transparency is the key to everything 😉

PS:
And it's the same for absolutely ALL blend modes in Photoshop!
OK, the blend modes work by ON/OFF (all or nothing). BUT, used as a team with transparency, a FINE setting can be made! 😊👍

@D Fosse 

Perhaps this example will make my work with TRANSPARENCY easier to understand. I'm not trying to convince you. Just to express the way I use transparency.

Here is my work:
- Calque_1 = Completely filled with 100% opaque BLACK pixels -> BUT rendered slightly TRANSPARENT with a layer mask
- Layer "Blue": 100% opaque BLUE pixels
- Layer "Green": 100% opaque GREEN pixels

So here I am with 3 layers, all 100% OPAQUE

The 100% mask is applied to the "Blue" layer using the "Layer Style". But this doesn't mean that the layer is completely erased! 

Some blue appears in the image 😉
Magic 😊

The result would be the same with a ‘Clear’ blending mode (but quicker to perform).
I hope you have a good weekend,

There is a point raised by Cyan_282 that is very valid these days and that is the discoverability of some functionality.

When I started with Photoshop (back with v7.0) an almost compulsory purchase was the Photoshop Bible. It was a very thick and comprehensive book that served both as a reference and a guide that you could thumb through and discover useful functions. Online searches only work as long as you know what to search for. I still have that v7.0 book and the chapter on Blending and Knockouts covers it comprehensively.

Another example would be how many users know about the Capture function in Photoshop? Hint - it is at the bottom of the library panel when you select My Libraries and click on the + symbol then select Extract from Image from the menu that opens.

My point is that there is a lot of useful functionality in Photoshop that users need pointing to. We often see requests for functionality that exists, and we need better guides and reference docs so that users can easily discover them. Some of the LinkedIn learning courses are quite good at pulling out these functions but a printed reference guide is easy to flick through.

Dave

I NEVER work with a whole image (for the top layer) !

Always transparent parts AND parts with pixels. In this case, the "Clear" blending mode comes into its own.

Don't get stuck on the idea of a layer entirely filled with 100% opaque pixels. I simply don't work that way 😉

That's the whole layer. That's the way it is.
I'm not missing anything. I understand the role of blend modes (which I use daily) 😊

My original request was simply to have the "Clear" blend mode for layers.
This would be VERY USEFUL, and would NOT delete the entire layer AT ALL, for all the reasons I explained above (have you read me?).

Transparency is the key to all this 😉
Thank you all for your help. You guys are awesome. Thank you 😍

PS:
I'm still holding out hope that one day I'll see the "Clear" blend mode for layers!

@Cyan_282 

I still think you're missing the big picture. You're focusing on the brushstroke - but this isn't the brushstroke, or a shape or whatever, it's the whole layer.

If you have two pixel layers, just images, no brushstrokes, and the top one is in clear mode - how would you expect that to look? If this is to behave consistently, I would expect that top layer to be completely invisible. In other words, it wouldn't matter if you put a brushstroke there; it would be invisible and for all practical purposes not there.

I'm not pretending to understand the math of blend modes, but for blend modes to be useful they have to behave in a consistent and predictable way. They can't just be convenient ad hoc tricks to achieve a certain effect that you want.

As Dave has brilliantly demonstrated, what you want can be achieved with existing methods.

Yes, I can see that. And your tip will help me a lot.
However, I still prefer the ‘Clear’ merge mode for TWO reasons:

ONE) Ease of use:
The current method (via ‘Layer Style’), requires the following sequence of operations:
1) Double-click on the layer = Open Layer Style
2) Click on "Blending options"
3) Go to "Advance Blending" -> lower the "Fil Opacity" to 0%.
4) "knockout" section -> Choose the corresponding option (Shallow or Deep)
5) Click OK (to close the window)
6) Return to the Layers panel -> Create a folder
7) Place the desired elements in the folder (to limit the masking effect)
END

IF the "Clear" blend mode existed, the operations would be as follows:
1) Select the "Clear" blend mode
2) Set the layer to "Clipping mask".
END

Note:

What's more... having folders all over the place (in order to limit this effect) will make the layer panel unnecessarily heavy (I use a lot of blend masks). The primary function of a folder is to group elements together. NOT to limit an effect...

TWO) Logic of how Photoshop works
The "Clear" blend mode would be immediately available, alongside the other blend modes.
Available and EASY to find.

The tip (that you showed me) is invaluable (and I thank you sincerely). BUT without your help (and this forum), I would NEVER have found this way of doing things, hidden deep in the "Layer Style" settings.

How many people miss out on this brilliant option ? Because it's "very different" compared to the rest of Photoshop (to obtain a blend mode).

Especially as the "Clear" blend mode already exists (for the brush) (there's NOTHING new to program)! All you need to do is add it to the list of blend modes in the layer panel !

Both of those are achievable today with a group and a knockout

Shallow knockout

Deep knockout

Dave

Thanks for the link 👍

To prevent the layer in "Clear" blending mode from affecting ALL the layers below it
I would obviously place this one as a "Clipping mask".

Illustrators (That's my job) use clipping masks a lot!

Here's what the "Clear" blending mode would look like if it existed for layers 😊

PS:
This is an ASSEMBLY I made to illustrate what Photoshop would look like with a "Clear" blending mode for layers. Seems simple to me, doesn't it?

There are two knockout modes - shallow and deep. Shallow goes down to the next 'stop point' which could be a layer outside the group or the clipping mask. Deep goes all the wway to the bottom layer, if it is a background layer, or transparency if it is not.

Some info here : https://helpx.adobe.com/uk/photoshop/using/knockout-reveal-content-layers.html

I still believe that a clear blend mode would not make sense and would not have the control available from knockouts. Remember a brush clear blend mode only interacts with the pixels on the layer being brushed onto. A layer clear blend mode would interact with the entire image formed by the layer(s) below - which is what a knockout set to 'deep' does.

Dave