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  1. #11
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    Quote Originally Posted by hopeandmemory View Post
    Is there somewhere I can look on a histogram to see if the channel is actually clipped?
    I'm at work right now but if I'm not mistaken you can do some type of a levels or curves window that will show clipping. I'll pull yours into CS3 when I get home this evening and see if it comes back to me. In CS3, can't a curves window be brought up and a choice for "show clipping"?
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  2. #12
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    Maybe? I don't know. I have never noticed it before, but I have a tendency to overlook things like that even (or especially?) when I am looking for them...
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  3. #13
    ttosifa is offline dPS Forum Member
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    Quote Originally Posted by hopeandmemory View Post
    What is the best way to fix a clipped or blown channel? I am needing to be calibrated right now, but some photogs on another forum have informed me that I have clipped the red channel in this photo. I am not seeing it, but I tried fixing with curves (only to get a green tinge in the midtones... this is a common problem for me which I don't know how to fix) and got the same response. I don't even know where to look or how to tell if it is clipped or blown. Help would be GREATLY appreciated!
    It's hard to fix in PS. I prefer to set my camera to show blinkies in the red channel when shooting people.

    It also looks to me like you've blown the reds in this photo, especially on her left side of her nose. It often looks bad because -- to my eye -- it gives a splotch or some splotchiness of a gross looking yellow. One way to see it is to open up a Levels layer and option-click (on a Mac, no idea on Windoze) the highlight slider. Look for the red pixels near the face. Those are your blown reds. Let go of the option button and look at that area in comparison to the nonblown areas. On a photo of the size you posted, it's there if you look. If you print a bigger version or do some types of color corrections, it often looks bad and more noticeable.

    The problem is that faces have a natural amount of cyan (blue green) in them. And I think that this cyan helps to form shadows on the face. An un-color-corrected photo in the shade often has a lot of cyan in it -- and you can tell just from the color that it was taken in the shade! Cyan is the opposite of red. So when you blow the reds on a large area of the face (100% red), there is 0% cyan. My theory (untested) is that the (trained) eye picks up on this by seeing the blown area as shapeless and splotchy because there is no subtle shaping of the face there. But I could just be full of sh..!

    EDIT: I think this is why it's so hard to fix convincingly. You can add cyan back in, but (under my theory) you've lost the information about the shadows that would make it look real. You just gotta be careful when clipping highlights.

    I had never even thought about blowing the reds until I read Michael Grecco's book in which he describes being very careful to avoid it. Once you see what it does, pictures just look bad with blown reds. And it's right where you want people to look! Now if I blow reds -- as shown by the blinkies on my camera histogram -- I reshoot. Period. Unless it's a once in a lifetime shot, in which I just grit my teeth. I have to close my eyes when looking at those photos!
    Last edited by ttosifa; 01-21-2009 at 09:45 PM.

  4. #14
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    Other than the possible fixes mentioned above, I've no idea how to fix this. The only input I can add is from my painting days. I was taught to make brown by mixing red and green, so it stands to reason that if you think your reds are blown, and decrease the level, you will increase the other component which is green. Since you have so much brown in your image (which is very nice btw), any adjustment will take you toward green or red. Have you tried adjusting from "Raw", instead of jpeg? You may be able to fix your reds without boosting the greens. Please post whatever fix you find, as this issue may become problematic to other members as well.
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  5. #15
    ttosifa is offline dPS Forum Member
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    Just thinking -- one thing you might try is adding a photo filter layer and choosing a cyan filter. This will add cyan to the whole picture. Don't worry about that. If you leave it at the default density of 25, the blown red areas will now have uniformly about 4% cyan. The problem is that it shouldn't be uniform -- it should be lower in the brighter areas and darker in the darker areas, and should mix in gradient fashion with the non-blown parts of the face.

    So, try adding either a green channel layer mask or a blue channel layer mask to the photofilter layer. Do Image -> Apply Image -> Channel: Green, Blending: Normal (all others default). How does this look in the blown areas? Just worry about the colors on the face. You can adjust the opacity of the photo filter layer, play with curves on the layer mask, etc. EDIT: I can't really tell with the low res image above; you'll need the high res version.

    The background doesn't look as nice with the extra cyan, so I'd just paint the layer mask black there to get the original.

  6. #16
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    Quote Originally Posted by lputman View Post
    I'm at work right now but if I'm not mistaken you can do some type of a levels or curves window that will show clipping. I'll pull yours into CS3 when I get home this evening and see if it comes back to me. In CS3, can't a curves window be brought up and a choice for "show clipping"?
    If you bring up the histogram tab and select the red channel - then position your mouse to the far right of the histogram (until channel 255 is displayed) - it will then show the number of pixels (see attached example).
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  7. #17
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    Thanks potterm, that I knew. I thought I've seen where you can actually see the image and it will show clipped areas. I'm going to see if I can find where I read/saw that.

    ttosifa, you always have such great input on color. Care to share what books you've been reading in this arena?
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  8. #18
    ttosifa is offline dPS Forum Member
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    Quote Originally Posted by lputman View Post
    ttosifa, you always have such great input on color. Care to share what books you've been reading in this arena?
    Thanks! (blush)

    My favorite book on color is "Professional Photoshop: The Classic Guide to Color Correction" (5th edition) by Dan Margulis. It's the only one I can think of right now that is an absolute must read, except for maybe his other book "Photoshop LAB Color," which is equally fantastic if you are interested in the LAB colorspace.

    I read a LOT, so I have picked up quite a few tidbits here and there, such as the Grecco statement in "Lighting and the Dramatic Portrait." The statement is, "If you are shooting without a tech crew, I suggest you open the image up in Apple's Aperture software or Photoshop RAW, and examine it to make sure that you have a good histogram. Look to see what areas have no detail in the blacks and if any of the skin tone has blown out in the red channel. Skin tone is the most critical, because if you have no detail in a patch of skin it will need extensive retouching." Like I said, I have not seen this elsewhere, but blown reds are easy to spot when you know what to look for. You can easily blow out the reds long before you get general highlight blinkies on your camera.

    I noticed something similar when shooting my new cats -- areas of virtually no detail -- even though the reds were not blown. Turns out I was blowing out the blue channel, so I have to change my screen whenever I shoot the cats to warn me.

  9. #19
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    Quote Originally Posted by lputman View Post
    Thanks potterm, that I knew. I thought I've seen where you can actually see the image and it will show clipped areas. I'm going to see if I can find where I read/saw that.

    ttosifa, you always have such great input on color. Care to share what books you've been reading in this arena?
    Ah, I understand what you mean. In Photoshop CS I do this using the Select-->Color Range dialog. I have two preset color ranges saved which look for black pixels and white pixels in the image respectively, allowing me to visualise lost shadow and highlight detail. You have to use the "Sampled Colors" option in the pull-down, and then select black (or white) depending on whether you want blown highlights or lost shadow detail to be shown. I expect later versions of PS give you an easier way of doing this...

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  10. #20
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    Thanks ttosifa, I've added those to my amazon shopping list.

    Martin, I'm going to try that method.
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