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saturation masking

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  • saturation masking

    I have recently plunged back in the book.
    I started on the section on saturation masking. Reading and re reading it seems the goal is to mask the blue bottles and vase so that the remaining colors can be changed. Going thru all the steps the mask that results masks the other colors but not the blue bottles which is opposite to the stated goal.

    I figured I made a mistake somewhere but I get the same result using the saturation mask tool. So what am I doing wrong?


  • #2
    You can use the same mask to accomplish either goal: isolate a particular color to keep it from change, or isolate the color to change it. This should all be described in what follows the exercise.

    In short: once the isolation is made, you can apply changes to the isolated area, or everything else.

    Make sense?


    • #3
      Partial mask

      I'm having a lot of trouble with saturation masking also. My problem is that it doesn't really isolate the blue bottles. A look at the mask, or control clicking the mask, will reveal that while the blue bottles are selected, so is a large part of the rest of the picture. This is by far not as effective a separation as the tone mask.
      For example, I often want to treat the sky differently from the foreground (levels, sharpening...). The blue of the sky seemed like a good way to get separation. Still, much of the green foreground is also partially selected.
      Even when I get a clean separation using tone mask (and painting a bit with white and black to complete the masking job), changes to levels in different directions for the sky and foreground produce good results, except for the transition point. I have tried to blur the mask (1-2 pixels gausssian) to smooth the transition, which helps. Is there a better way to isolate bright sky verses dark foreground without artifacts at the border?


      • #4
        There is a marked difference between selecting by tone and selecting by color. Selecting by tone focuses on lightness/darkness and selecting by color focuses on a color or color range.

        If you become adept with the use of the tools as I describe them, there is really very little you can't select and isolate. The means of selection will include the neutral toned areas in the selection made in this way...and you won't get a neat selection around the bottles. The point is not to work with SHAPE, which would again be a different type of selection.

        If you follow the instructions in the book, and you get to the end, what happens? You should be able to change the color of the bottles without changing anything else (or change everything else without changing the bottles). That is the only goal.


        • #5
          I think some of the confusion arises because the mask looks wrong, even though it isn't. The expectation is for the mask to be just the bottles. If you use the mask it does work as expected. This is because the magnitude of the effect is affected by the transparency of the mask -- the more transparent the mask is, the less the effect.

          When using your own images, the success or not depends highly on the image and the colour you're trying to separate. Richard's bottle image shows this quite nicely -- the blue bottles are easy, but the red flowers aren't because of the red window frame.

          Remember, Saturation masking is a tool in your [image manipulation] armoury -- it may not be the right tool to do what you want, or has to be used in conjuction with other tools. Selecting the right tool(s) comes with experience (and I admit I'm still learning).



          • #6
            saturation masking

            I appreciate the responses.
            But I still don't quite get it. Richard I did read on and see how you can do the blue bottles or the background. But as one of the other posts notes this there is blue in varing degrees in the rest of the picture. I don't see how you can use this type of masking to isolate colors in a complex picture.
            Wouldn't it be easier to do a correction globally, use a mask layer and paint in the correction you want or as you did with snap shots and the 'history brush'?



            • #7
              I have not seen the images in question, but I was under the impression that they were not complex and that this method would select the bottles without other elements.

              As Richard suggests later on, other methods or combinations of various methods may be needed - depending on the task.

              Stephen Marsh.


              • #8
                Don't forget you can just work on a part of the image. Either use the lasso to roughly cut out what you're interested in to another layer and build the mask from this cutout layer, or generate the mask and then delete the unwanted parts of the mask.



                • #9
                  I don't see how you can use this type of masking to isolate colors in a complex picture.
                  Well, the bottle image IS a complex picture. The blues you will isolate are not necessarily distinct in the image, and the vase and plaque in the background contain blue as well. The technique is meant to mimick color range behavior (that you don't have in Elements), NOT to selectively isolate shape -- unless the shape is wholly color based.

                  This an example of the type of change you might make to an image. As the blues here will potentially require work to get the best result in print, isolating them for correction is a valid procedure. all you want is the color. If you want something else (e.g., the shape of the bottle), don't use saturation techniques. Color can aide in selecting shape in some cases...but it is not an absolute.

                  Once the blue area is isolated, you can limit that further with selection or OTHER TECHNIQUES, as Paul suggests. You can possibly use the History Brush technique, as you suggest. The saturation technique was integral to the CMYK separation and other complicated separations (e.g., adding in a spot color, and extracting the color areas where it might be most effective). Of course I can't cover every angle in 300 pages...

                  Stephen, the bottles will not be isolated as shape, but you can adjust the color...which is the point of the exercise. I think you'd enjoy the book and techniques.


                  • #10

                    Thanks I think I understand the purpose of this kind of masking now. For example in the bottle picture if the blues(or reds or whatever color) had to be adjusted for a particular printing they could be isolated. Is this right?


                    • #11
                      Isolation by color is the ENTIRE point. yes. Never forget you may need to combine techniques to get the result or selection you actualy need.

                      there are many techniques to get a result, but often a combination will be neccessary to work with a unique image.


                      • #12
                        I have quite a few questions about this process, but I'm having trouble getting my posts to come though. This is just a test to see if I can get this message on the board.

                        Sorry ....
                        Last edited by beaner; 08-17-2003, 03:13 PM.


                        • #13
                          Ok, I see my post so I will attempt to ask my questions. I am just learning how to use saturation masking. As the book suggests, I am trying to master the manual technique first. So following the instructions in the book I encounter a problem with step #5 (Preparation). "Create another Fill Layer and fill it with gray (put 50% H in the HSB fields in the color picker; S and B should be 0%). Name this Commit Mode 2.

                          1. What should be the active layer for this step?

                          2. If I use the Mask Layer as the active layer the Commit Mode 1 Layer combines with the Mask layer. Why? The way I worked around this was to use the backround layer as the active Layer, but then I believe it throws off the order of the layers. In the end I switch them around so from top to bottom I have: Saturated Colors, Commit Mode 1, Commit Mode 2, Mask and then Backround Layer. Is this the correct order?

                          3. When I enter 50% into the H in the HSB field in the color picker and 0% into S and B I don't get gray. I end up with Black. Could someone explain this. The only way that I am able to get gray is to put 127 into R 127 into G and 127 into B. Will this work instead?

                          4. My last problem is with step #15. I can't seem to get the Satruated Colors Layer to merge with the Commit Mode 1 Layer unless I use the "simplify layers command on "Commit Mode 1". Is this an acceptable thing to do?

                          Thanks in advance for your help!


                          • #14
                            Errata link

                            Some of your questions can be answered here;
                            Domain for Sale. Request Price. What Are the Advantages of a Super Premium .Com Domain? Increased Traffic. Search Engine Ranking. Brand Recognition. Immediate Presence. Higher Profits. Great Investment. #1 in Premium Domains. 300,000 of the World's Best .Com Domains.

                            A few errors crept into the book. CaseyJ


                            • #15
                              Those same darned errors...Please do check where Casey suggested. The reprint should have these corrected -- as far as I know on the way to be printed again soon.

                              If you still have trouble after checking the errata, please come back here again!


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