Editing Lightness, Chroma, and Hue separately

Hi.
I’m trying to follow Elle Stone’s tutorial on how to separately edit Lightness, chroma and hue.
I’m stuck at the point where I’m supposed to create a chroma mask:

1- Make a copy of the layer “Visible + Channel mixer to add Chroma”.
2- Extract the B channel using “Colors/Component Extract” and select the LAB “B” channel. Change the layer name to “LAB B channel”.
3- The resulting extracted layer will have the wrong tonality because the “Component Extract” procedure doesn’t take into account the TRC of the layer stack. So drag the B channel layer out as a new layer and assign to it a V4 RGB working space profile from my profile pack that has the “LAB L” companding curve. These profiles all have file names ending in “-labl.icc”.
4- Drag the resulting layer back to the original layer stack. Go ahead and delete the originally extracted layer.
5- Make a layer mask using “Grayscale copy of layer” and load this mask as a selection.
6- Add the selection as a layer mask to the original “Visible + Channel mixer to add Chroma” layer, and then delete the modified extracted layer.

My questions:

  1. Is this procedure still necessary in the latest 2.9 version?
  2. If so, since I changed the color profile, at the very beginning of the workflow, to builtin sRGB (I’m not working with the CCE version), should I still perform these steps?
  3. If so, when I change the profile to the v4labl.icc as stated, does this change apply only to the topmost visible layer, or will it change the whole stack? In the end, since I wasn’t working with a linear srgb (CCE version), should I get back to the sRGB builtin profile?
    Thanks in advance
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@gadolf If I recall correctly, the intention is to generate an exaggerated chroma mask. That is the reason that she used the mixer rather than simply the chroma channel. Step 3 sounds like you could apply TRCs to a certain layer. However, some things may have changed since June 2017, so it might be best to contact Elle (maybe by email, since she withdrew from this forum). Or better yet, you could give it a test yourself using sample points.

PS Using CCE is no longer advisable. It was a stopgap.

PPS To be clear, colour management deals with profiles in the working space. Therefore, it is unlikely that you could colour manage on the layer-by-layer basis. However, you could always convert back. That is one of the reasons that Elle generates layers from visible and sorts them in groups, etc.

That’s what I was about to conclude myself. I understand that, by doing that, you squeeze the raw to get the most information about chroma you can, and then, by masking it, you choose where you want to reveal that info in the image.

That was my main concern about this procedure, switching color spaces forth and back and melting all pixels. So, normal procedure, apparently. But she doesn’t say that I have to get back to sRGB, where all procedure was being handled…

Also, what I find confusing, is how she handles the working lab layer: first she rips it from the layer group, then she changes color space, then she gets the lab layer back to the layer group, then she deletes it and then she creates a mask… but shouldn’t the final mask be produced from the deleted layer? Is the deletion step just out of placement in the text?

I just re-read her tutorial. It would have been clearer if she included a screenshot for every step.

  1. Do not worry about changing working spaces. Moreover, she isn’t converting but assigning; i.e., no pixel values are altered on the other layers, only how values relate to one another.

  2. There should be two deletion steps:
    (a) for the copy of Visible + Channel mixer to add Chroma; and
    (b) for the Grayscale copy of layer (from which the mask is generated).