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Making a Mask from a Luminosity Layer

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  • Making a Mask from a Luminosity Layer

    Let me start off by saying I am very new to the world of digital imaging. I am working through Richard's wonderful book and following along with each exercise in order to gain a full understanding of the whys and hows. In chapter 3 he isolates the shadows in an image by converting a luminosity layer into a mask. During the procedure he creates an empty, transparent layer and then merges the (modified) luminosity layer on to it to create the mask. I'm trying to determine why this step is necessary other than the fact it doesn't work otherwise. Why wouldn't the luminosity layer, which had already been modified to include the requisite transparent areas, suffice as a mask without the need for merging with a blank layer. The engineer in me needs to know to foster my understanding. Forgive the long post, but I couldn't find a more concise way to ask.

    Thanks in advance,

  • #2
    Hello, Jeff, and welcome.

    Regardless how long any of us have been messing with digital, we're all still new with it to some degree.

    Until Richard jumps in to the rescue (he usually checks the forums on a regular, almost daily basis), I'm looking through his book (just got it, but haven't read it). Maybe I'm not looking close enough, but I'm not seeing anything about layer or luminosity masks in Ch 3.

    Give me a specific page # you're working from and I'll see if I can decipher your question.



    • #3
      Thanks DannyR for getting back to me. My question stems from step 13 on page 86 of Richard's book (also, indirectly, step 3). The "Mask" layer is simply an empty layer, so merging an existing layer into an empty, transparent layer seems like a wasted step to me. Why can't the "Masking Tone" layer stand on its own? I have, of course tried this on my computer, and it doesn't work without step 13 -- I just don't know why. Without step 13, after grouping the "Isolated Shadows" layer with the "Masking Tone" layer, the result is the horse's silhouette showing from under the transparency grid which leaves me totally baffled. Anyway, I'm just trying to understand the concept fully before I move on and get more lost.

      Thanks for any insight you have on this,


      • #4
        I can see why this was a little confusing, Jeff. I played these steps in my head and on scratch paper a couple times. "On paper," I see no value add from the final merge, either.

        Since Photoshop doesn't have the "Clear Grayscale" function (and I don't have Elements), the only thing I can think of is "Clear Grayscale" may be a function that on-screen appears to have taken effect, but doesn't doesn't become permanent until the layer to which it is applied is merged with a blank one.

        That's a pretty lame shot in the dark.

        The good news is when Richard gets back on line, we'll both learn something!



        • #5
          Thanks DannyR,

          I appreciate your time on this. There's no indication on screen for what "Clear Grayscale" is doing behind the scene, but visually it turns all of the white area to transparent. Then after the merge with the empty layer, there is no visual change to what is on screen that I can tell. I've played with it a number of ways: with and without the "Mask" layer, grouped and ungrouped, and turning on/off various layers. Nothing seems to give the correct result except Richard's way. I'll be anxiously awaiting his input or anyone else's who can shed some light on the issue.

          Thanks again,


          • #6
            Jeff - this one puzzled me too. Looking at the clear greyscale layer before it is committed I notice a little "f" next to it - which means the greyscale is being cleared using a layer style - confirmed by checking the undo history - my guess is something to do with the advanced blending options stuff which I haven't yet explored in photoshop. Now I don't know too much of the technical side of the way the layer styles work, but it seems to be all smoke and mirrrors until the layer style is permanently rendered onto the pixels, in this case by merging down onto a transparent layer. I would have thought that just simplifying the layer with the layer style would have had the same effect - and a quick experiment seems to confirm this. i'm not sure what advantage the merging down has over simplifying.
            Susan S.


            • #7
              Ok, that makes sense to me. I am not familiar with layer styles at all, but your explanation is undoubtedly right on the nose since the Simplify command appears to accomplish the same effect. Now perhaps someone intimately familiar with layer styles can tell us if there is an advantage to merging to a transparent layer over Simplifying the layer.

              Thanks, Susan, so much for your insight.


              • #8
                Well well...

                This is actually a really good question. And it's about one of my favorite tools.

                That the functionality that gets used is not something I can evoke in Elements as part of the interface so you can see it -- and regretfully it ends up being'magic'. I actually use something called Blend If in Photoshop.

                You see, the means by which I get around the problem of converting the mask only makes the layer look like it is transparent. It actually has solid qualities -- you just can't see the pixels -- they get blended out because of the setting. If the layer is not somehow committed so the visible effect is made actual, flattening the layer can lead to unexpected results...and loading it as a selection will load the entire layer -- even the pixels that you can't see -- as part of the selection.

                Committing the change can be done with Simplify, as you note, or by creating another transparent layer and merging down. The result should be exactly the same. The reason one solution was selected over the other in making the action was probably because the menu equivalent of Simplify isn't in Photoshop -- or it is, but not in the same place. Or (and I can't confirm this either way) testing at the time suggested to me that there were situations where merging down was better...Or I just felt like doing it that way at the time...

                I don't really talk in depth about Blend If in the Elements book, though I think I mention it. I don't only because the interface doesn't really go there (well, in any direct way that I found). That particular feature is one that most Photoshop users don't either use or understand. As it really is a difficult tool to grasp, I tried to simplify the use...and while I don't like creating 'magic' tools, this one almost had to be -- kept me from going on about it for 50 pages.

                Please let me know if that clarifies enough or if you need more information. I'd be glad to discuss it until it makes sense!


                • #9
                  Thanks Richard,

                  That explains it well for my current level of understanding of this subject. Are there other tools besides "Clear Grayscale" that will require simplifying or merging to complete the step? I've only begun Chapter 4 so far, but I look forward to working through each exercise to enhance my understanding of the material.

                  Thanks again,


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