13 Replies Latest reply on Jan 7, 2018 6:51 PM by Theresa J

    LUMINACE MASK

    fabrizio211945

      When I like make a luminance mask, I can go to the RGB channel and click on it.

      A selection is made and all changes should take place only on the selected area.

      Instead, the changes take place over the whole image.

      If I create a selection with another tool, for example fast mask, everything works perfectly.

      I tried using luminance masks on another computer and everything goes perfectly.

      I don't know why but I would be very happy if I could solve the problem.

        • 1. Re: LUMINACE MASK
          c.pfaffenbichler Level 8

          I can go to the RGB channel and click on it.

          Do you mean cmd-click?

          A selection is made and all changes should take place only on the selected area.

          What changes?

          Don’t you use Layer Masks?

           

          Please post screenshots (including the pertinent Panels) to illustrate your problem.

          • 2. Re: LUMINACE MASK
            D Fosse Adobe Community Professional & MVP

            Don't be fooled by the "marching ants" marquee. That's just the 50% boundary. A selection isn't necessarily either/or, it can be gradual.

             

            The whole point of a luminance mask is that white is fully selected, then gradually less selected down to full black, which is not selected at all. So anything you do in that selection works on the whole image, but with a light/dark gradient.

            1 person found this helpful
            • 3. Re: LUMINACE MASK
              norman.sanders Most Valuable Participant

              luminance blend.jpg

              As an alternate approach I have found a Luminosity Layer to be helpful, particularly in images such as the one shown here. The method:

              1. Add a duplicate layer

              2. Choose Image > Apply image … Channel: Green is usually best. Blending: Normal

              3. Change Layer blending mode from Normal to Luminosity

              5. Image > Adjustment Curves.

              6. First mark and then bend the curve to increase contrast in the flesh tones. Don’t fret if you later realize you overdid it a bit, as I see now. That can be adjusted with the Opacity slider.)

              1 person found this helpful
              • 4. Re: LUMINACE MASK
                D Fosse Adobe Community Professional & MVP

                Yes, luminosity is an incredibly useful concept. I use luminosity layers and luminosity masks all the time, to the point where I suspect it's my most frequently used tool.

                 

                It's worth noting that luminosity is not the same thing as RGB brightness. Luminosity is basically the L channel in Lab. The reason it's so easily available in RGB, is that Lab is used as Profile Connection Space in color management operations, so there is always a set of Lab numbers "in the background", whatever color space or color model you're working in. Any color or tone always has a Lab reference.

                 

                What distinguishes luminosity (as opposed to brightness), is that it's entirely separate from any color components. This means that any color's inherent lightness is taken into consideration. A bright yellow is light, but a deep blue is dark. They don't have the same luminosity. In the RGB model they will be treated the same way and have the same brightness.

                 

                I see you finally got your true avatar up, Norman, it was about time! 

                • 5. Re: LUMINACE MASK
                  norman.sanders Most Valuable Participant

                  MGL.jpg

                  Dag, just a carryover from my previous life in the CMYK world. My first choice was Magenta but it was always too heavy. Lightness channel was usually too thin. And G seemed just right (sounds like the three bears and porridge thing) so I settled on Green -- always with Color Sampler & Curves and often with the Opacity slider. It is quite flexible.

                   

                  And thanks for the Lab Man avatar thumbs-up. I owe that terrific job to Trevor.    

                  • 6. Re: LUMINACE MASK
                    D Fosse Adobe Community Professional & MVP

                    Yes, using the green channel is a special variety that probably works especially well for skin tones.

                     

                    My comment was of a more general nature.

                    • 7. Re: LUMINACE MASK
                      Trevor.Dennis Adobe Community Professional (Moderator)

                      A wee plug for Sven Stork's Interactive Luminosity Mask It can target Saturation as well as Luminosity, and with specific tonal ranges, and unlike the Tony Kuyper (main) Extension, it is free.

                      https://exchange.adobe.com/addons/products/12307#.WkqjtzfRUUE

                      • 8. Re: LUMINACE MASK
                        fabrizio211945 Level 1

                        If I make changes, with curves, for example, changes must only take place on the selected area. Instead in my computer the changes happen on the whole area and therefore the mask is useless.

                        • 9. Re: LUMINACE MASK
                          c.pfaffenbichler Level 8
                          therefore the mask is useless.

                          What is the Selection/Layer Mask exactly?

                          Please post meaningful screenshots that include all pertinent Panels (Layers, Channels, …).

                          • 10. Re: LUMINACE MASK
                            fabrizio211945 Level 1

                            Unfortunately I am Italian and I do not know English well.
                            Once you open a photo in Photoshop, going to the Channels panel and clicking on the RGB Channel, all areas of the photo with a brightness above 50% are highlighted, with the classic moving ants that delimit the selection. This is a first selection from which we can obtain other selections with less bright areas.The selection obviously serves to be able to operate with modifications exclusively on the selected area.This is what I did until two or three months ago.
                            Now the changes do not take place only on the selected area but on the whole image. I do not know why. Maybe I didn't say it clear enough. I don't want to know how to create luminance masks, I want to know what happened because I can't make them work anymore.

                            • 11. Re: LUMINACE MASK
                              D Fosse Adobe Community Professional & MVP

                              We need to get this out of the way before we can move on here:

                              the classic moving ants that delimit the selection

                               

                              We need to be very clear on this: it is not delimiting the selection. It is not fully selected inside the marching ants, and fully unselected outside. The marching ants is a 50% indication, this is the boundary where the pixels are 50% selected. Halfway selected and unselected.

                               

                              If I ctrl-click the RGB channel on an image I get this:

                              selection_1.jpg

                              But the actual selection looks like this - light is more selected, dark is less selected:

                              selection_2.jpg

                               

                              If we can agree on this, but this is not how it works for you - then we can move on to figuring out why.

                              • 12. Re: LUMINACE MASK
                                fabrizio211945 Level 1

                                Why? That's what I'd like to know ....

                                • 13. Re: LUMINACE MASK
                                  Theresa J Adobe Community Professional

                                  Why? Because a mask can have all values from white to black and marching ants only show the boundaries. It doesn’t show all of the gray areas. I like to switch to quick mask when I have a selection so that I can view all of the values as an overlay. If you use the tild key while in the quick mask mode, it will hide the image pixels and show just the pixels of the selection in greyscale.