Desaturating A Layer …

[Dr_No]

¡Hola, amigos! Yo soy – ? – ‘bien’ ? That's close enough for government work, right? Right. 

Today’s Big Question: How You Desaturate Dem Layer What Got Dem Color In It, Hah?

A simple question asked by a Simple Mind. Please ’splain me where I can find a simple equivalent of the Photoshop command Layer > Desaturate to remove color from a layer so that it becomes black and white and still responsive to Blend Modes. I've tried the HSL panel with spotty results. If HSL FX is applied as a PARENT layer, it functions marginally well. When the HSL FX are applied as the CHILD layer (a/k/a 'mask'), it's a whole ’nuther story. At that point, any ‘finesse’-ness is gone.

Adjustments made to the Child mask layer do not play nice with the Parent layer above. Insofar as experimenting with other FX (live or not), I continue to come up empty. HSL appears to be as close as I can get to where I want to be, but it's half-a-league, half-a-league as regards color removal with xparency FX and blend modality intact. 

In a perfect world, there should be a way to electronically tell the ware ‘Hey! I want the color removed from this layer. Just do it, ’kay.’ … but if there is such a method, I haven't yet found it. Oh please oh please oh please … Prithee, envelop me in thy Secret Sauce which removeth Color from a layer so that it majickally becometh un Noir et Blanc (and the Blend Modes are still next door). Thanks in advance to all.

[RichardMH]

Does putting Black and White as a child layer give the same problems?

[NotMyFault]

I don’t get what the exact issues are. It seems the main issue is the difference between

• getting a desaturated layer (destructive workflow) vs
• handling 2 separate bitmap layers and adjustments layers 

In case you want to use the desaturated result in additional edit steps. E.g. to apply a blend mode.

The basic trick: group both layers, and apply the blend mode to the group instead of the other layers. When the adjustment layer (for de-saturation) is open, lick "merge" instead of apply. This should behave almost identical to a (single) desaturated layer in PS.

Almost means that there are some restrictions, both  „by design“ and by unfixed bugs. To overcome, you can simply apply „rasterize“ to the group, to get what PS delivers in one step.

It seems to be a „by design“ decision of Affinity to offer destructive versions of filters, but do not offer destructive versions of adjustments.

PS:

the underlying problem in the situation (nested HSL or B&W adjustment)

Target: you want a desaturated layer and apply a blend mode to the result (blend of both layers)

if you change the BM of the bitmap layer, it gets applied before the adjustment (you want it applied as final step)

if you change the BM of the nested layer, now Affinity applies the BM to the adjustment layer individually and blends this with the bitmap layer (again not what you want, you want that applied to the result of both layers blended).

The difference probably does not matter in most cases, but can become a deal breaker in other situations, e.g. having more layers below the bitmap layer.

It is similar to basic arithmetic addition and multiplication and parentheses to control the sequence of execution.

 

 

[NotMyFault]

To say it mathematically in a functional notation:

 

P pixel layer

A desaturate adjustment

BL blend of two layers

BM blend mode applied to a layer

(1) PS: desaturate layer, apply blend mode to the result

res-ps= BM(A(P))

(2) adjustment atop pixel layer, BM set on top layer

res-2 =BL(BM(A(P)), P)

(3) adjustment nested, BM set on pixel layer

res-3 =BL( A(BM(P)), BM(P))

(4) grouped and BM set on group level

res-4 = BM (A (P))

Even if the formulas are too much mathematical for you, you can see that only res-4 is the same formula as res-ps.

[walt.farrell]

5 hours ago, NotMyFault said:

It seems to be a „by design“ decision of Affinity to offer destructive versions of filters, but do not offer destructive versions of adjustments.

The destructive version of an adjustment is easy: just click on the adjustment thumbnail to get the dialog if it's not already open, and  push the Merge button.

[Dr_No]

Hello again, and thanks to all for your contribution to arriving one day in the not-too-distant future at La Soluciòn … and the trip continues (even as we speak).

RichardMH: The Majick 8-Ball says ‘Yes’ …

NotMyFault: First, thanks for your confidence that I'm ‘mathematical’ (if it's beyond the ‘2+2’ stage, I'm lost). I almost want to flatter myself and believe I'm comprehending the solution you advance, but that would probably be overestimation by a factor of at least 2x on my part. I do, on the other hand, grasp the concepts you present.

What I'm attempting to realise in AP is: (a) Base Layer is the color image layer; (b) Layer atop BL (L1) is the layer to be converted from color (let's say it's a sheet of textured yellow paper) to BW. Goal: Remove (desat) all yellow from (L1) without rasterising to convert it to greyscale and then use Blend Modes to adjust its FX on BL. If I HAVE to rasterise the layer to achieve that, well, I'll have to rasterise the layer, yes? Please advise …

Walt: Thanks again for your input. I'll assume that the term ‘adjustment thumbnail’ = ‘target layer’, yes? If that assumption is correct, then I should (extending the ‘textured yellow paper’ from above) click on the ‘TYP’ thumbnail to force-present the dialogue, and select ‘Merge’, yes? That seems to be worth a try. Best result is that it works, yes? 

Thanks again to all … I'm off once more To See The Whizzard …

[walt.farrell]

15 minutes ago, Dr_No said:

What I'm attempting to realise in AP is: (a) Base Layer is the color image layer; (b) Layer atop BL (L1) is the layer to be converted from color (let's say it's a sheet of textured yellow paper) to BW. Goal: Remove (desat) all yellow from (L1) without rasterising to convert it to greyscale

The obvious answer is:

1. Select L1 in the Layers panel.
2. Click the Adjustments icon at the bottom of the Layers panel and choose a Black & White Adjustment.

 

[Lisbon]

Hola Dr_No.

12 hours ago, Dr_No said:

...equivalent of the Photoshop command Layer > Desaturate to remove color from a layer...

The closest i can think of:
Edit > Fill (Shift+F5) and choose a neutral color (black/white) set to "Colour" blend mode

Dont know if this will work with your workflow, but you can try to do the same non-destructively by opening Layer Fx:
Select "Colour Overlay" and choose a neutral color set to "Colour" blend mode

[RichardMH]

If you desaturate the layer with HSL or whatever then use merge down you get a single desaturated layer.

[Dr_No]

Walt, Lisbon, and RichardMH … the technique that finally approximated (but didn't duplicate) Photoshop’s Layer > Desaturate command was a 'kinda-sorta' combination of all three approaches. Easiest method was applying a HSL layer to the image to set a correct value for the ‘look’ and ‘lightness/darkness/texture’, then make it the Child layer. Once the proper values were plugged in, it was possible to click the Parent layer to pick a blend mode to approximate the look and ‘feel’ I wanted. It's not what could be called 'intuitive' by any means; rather more ‘blunt force and immediate trauma’, but it provides the closest match to the ‘look’ I wanted. I can remain hopeful that a true Layer > Desat command will be putting in an appearance in future iterations of the ware, yes? Thanks again to all for your assistance.

[Wosven]

It can be a mess of layers and masks, etc. to recolour some part without modifying the background.

Since it's not really a science, here an example file of some cover I did using a scan of characters I needed to move and recolor also. The good point was the "grunge" aspect that give more leeway...

But at some point, I needed masks, duplication, erase white paper...

couv_petits_coeurs_cachotteries.afphoto

[kaffeeundsalz]

8 hours ago, Dr_No said:

I can remain hopeful that a true Layer > Desat command will be putting in an appearance in future iterations of the ware, yes?

I dare to doubt that very much. There already are a number of ways to desaturate layers, and Serif has no interest in precisely replicating Adobe Photoshop's behavior.

[Dr_No]

Wosven … love the textures you've used in that example. Quite nice. I'll be studying some of those FX, too. Thanx for the send.

 

Kaffeeundsalz, danke - you're probably right. If I were in Serif's position, I'd probably feel the same way (even tho’ that feeling is at the moment a bit of a bother during the execution phase of the process).

[iconoclast]

There are really many ways to turn colored images into greyscales. If you don't like the filters "Black/White" and "HSL", you can also create an additional pixel layer, fill it with some sort of grey (even black or white) and apply the blend mode "Saturation" to it.

Another nice opportunity, I used for a long time, is the filter "Simulate Film" in the "Color" category of the free G'MIC plugin (more than 500 additional filters). It contains a list of different presets that simulate classic black&white photo films. But unfortunately this is a destructive method. There are also some other filters in this plugin that can desaturate an image.

Another opportunity could be to use a LUT. This would be a very easy and non-destructive way, if you can find a LUT that fits your needs.

The roughest way would be of course to change the color space into greyscales.

[Dr_No]

Iconoclast, I'd love to use G'Mic, but everything I see at its site states that they're ever so sorry, but Mac users are out of luck when it comes to using their ware. Granted, I may be (and probably am) overlooking something staring me direct in the eye, but I found no link there to d/l a Mac version of G'Mic. That's a shame, ’cos Olivio has put out a great tute describing how to use it. The 'Simulate Film' option would probably have done the trick. Tried the LUT solution, but it required much more input and fiddly-ness that wasn't rewarded with a satisfactory result.

[Dr_No]

Thanks to all for your input and comments. If you (like I) have been wondering ‘What's he on about anyway? And why?', I've attached L'Image Final with this so you can peruse it at leisure. The FX were needed for the overlays and textures, not so much for individual pieces 'n parts of the image … Enjoy, and thanks again.

[iconoclast]

7 minutes ago, Dr_No said:

Iconoclast, I'd love to use G'Mic, but everything I see at its site states that they're ever so sorry, but Mac users are out of luck when it comes to using their ware...

Yes, sorry, I always forget that. That's really sad.

[R C-R]

2 hours ago, iconoclast said:

If you don't like the filters "Black/White" and "HSL", you can also create an additional pixel layer, fill it with some sort of grey (even black or white) and apply the blend mode "Saturation" to it.

I think the blend modes "Hue" & "Color" will do the same thing, right?

[walt.farrell]

2 hours ago, iconoclast said:

Another opportunity could be to use a LUT. This would be a very easy and non-destructive way, if you can find a LUT that fits your needs.

As you say, there are many ways. Lately I've been using a Gradient Map Adjustment, for example.

[Alfred]

1 hour ago, walt.farrell said:

there are many ways

Please see: