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What layers are the actual Calculation?

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  • What layers are the actual Calculation?

    I have a bit of trouble getting my head around the concept of Calculations. I figured that with some use in practical applications, I would soon understand. I still don't get it.

    Chapter 6 of the book.
    Making a selection of the Object (Calculations)
    Step 5. (p156) "Merge the layers used in the calculation, and rename the result Orchid Selection".

    What layers are the actual calculation? I used ALL layers to get to the "result", but I doubt the intent is to flatten the image. Can anyone shed more light on the subject please?


  • #2
    A calculation is like using the image as a math problem -- adding and subtracting portions to end up with a result different than yet very much based on the original. Calculations are really explained in Chapter 5, p. 129+.

    In the calculation you are looking at, the Green, Green Copy and Red channel are used to help isolate the flowers. This can save quite a bit of time that you would otherwise have spent doing manual masking of that same area. It should look the same if you flatten it, I guess, but really you want the Green, Green copy and Red to merge, leaving the background intact.

    That help?


    • #3
      Thanks for the reply Richard!

      If I did choose to flatten at step 5 (i tried this) the rest of the steps don't work. As it is... Rename the result in step 5 is also pointless, because as soon as you hit Clear Grayscale, then Commit Transparency, You are asked to rename the layer again.

      I roughly understand step 6. "get a brush and touch up the rough selection"....

      What if I want to partially select some of flower? will paint with some degree of gray get the job done?

      This step calls for painting in white on much of the flower detail, that shows up black. This is a really nice selection tool, I am just trying to fully understand all the uses.

      Yes I have read p129+ several times actually, but still don't understand what calculations are, rather I am finding more what they do.

      Sorry I am so poor at explaining things so you can understand what I mean. (I am trying )
      You have been great help Thanks!


      • #4
        Same Page 156...

        Using The Selection to Isolate the Object

        Steps 1-3

        Folowing this exactly as the book says, I end up with the background being copied not the Orchids.

        Steps 4-6

        Exactly folowing the steps gives me the Orchids layer, and not the background.

        These procedures will mean you have to rearange the layers in the palette to get the same looking result as shown in figure 6.10. This also means you will have to delete the selection layer to get the result shown. These steps are not in the book.

        If I did NOT paint white over the entire selection area of the Orchids in step 6 of the calculation mask, my result showed partial selection of the Orchids, and the resulting blur (following section) didn't turn out quite right. So the use of gray could be used for a partial selection I guess.

        It is so hard to try and follow something exactly as shown, only to discover that the steps must be interpreted first. I guess in the end this should really drill in the procedure, but right now it adds to my confusion instead. Its really damaging to my confidence


        • #5
          I have no idea what happened there, except that i know it WAS right at some point in the writing. Errors get added in process sometimes usually by last minute decisions, but sometimes by 'corrections' where in a rush I nod in the general direction of the development editor or project manager while typing like a fanatic. It is the concept you want. Step 3 says copy/paste the orchids...if you are getting the background, you should invert the selection.

          Granted, the steps should be right, but somehow something got removed or moved. In any case, the book shows how the layers should look...If you go through the steps and do everything and they don't look like that, invert the layers so they do. Throw out the selection layer if you want, or just leave it shut off...doesn't matter. There are lots of things not specifically stated by this point in the book as the book is advanced. I am not saying that means it should be sloppy, completely agree it should have an extra step (actually just duplicate the second part of the 4th step to the first step and there you go...) but in this case there should be enough information to go on.

          ALL that aside, I appreciate the comments. Really. This is the only way i can see what goes on in user hands, and it DOES improve what I do (and gives me warning for next time/where to look for problems in the process of editing and revision). if I sound a little gruff...I am typing like a fanatic on the next book (a photoshop one).



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