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Thread: Exposure

  1. #1
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    Exposure

    This arises out of Frank's question over in the POTD thread.

    Quote Originally Posted by sparkie1263 View Post
    Pete, can I adjust that in Bridge?? Will it be the same? Should I bracket shots to get the right EV?
    Thanks Frank
    Frank, by all means bracket when you're not sure of the exposure. Sometimes you just have to let the highlights blow out in order to preserve detail in the subject and in this case the highlights are all sky and no detail to speak of anyway. I've mentioned letting the sky blow out in a previous post (second page) http://www.dcresource.com/forums/showthread.php?t=45250.

    It's certainly possible to tweak it in PS but it won't be the same as getting it right in camera; you can't put back the shadow detail that was lost and the underexposure begets a noisier image as well.

    You can see that the Osprey pixels are all concentrated into the bottom two thirds of the histogram, the top third is all the lighter pixels of the sky and you can clearly see the clipped shadow detail in the "wall" of pixels at the left.
    Name:  Osprey 01.jpg
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    In this screen shot you can see I've dragged the slider way left of the sky pixels. This brings out more detail in the Osprey whilst the sky is totally demolished and some highlights on the bird blow out.
    Name:  Osprey 02.jpg
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    With the layer mask active on the levels adjustment layer, using a black brush and 20% opacity we can paint the detail back into the bird. Do the same at 100% to the sky.
    Name:  Osprey 03.jpg
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    And that's about it apart from using a hue/sat adjustment on the sky. The detail is improved but nothing can be done about the clipped shadow detail which is gone for ever. This process should work better on the original image than on this low res one.

    Before and After (or rather after and before).

    Name:  Osprey 05.jpg
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Size:  234.3 KB

  2. #2
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    Just after I posted the above answer to Frank's question, Elisha came up with this Portrait which I am about to mangle. So apologies Elisha, no real criticism intended, this is just to illustrate the point and expand on the crucial need to judge the in camera exposure correctly (or bracket if you can't).

    The first thing to say here is that the overexposed brightness of the shirt is pretty distracting as it inevitably draws the eye. The second thing is that in this case, unlike the sky (not part of the subject and therefore disposable), in Franks' Osprey the white shirt is part of the main subject and contains required detail.
    Here, the histogram tells the story with the blown white pixels of the shirt piled into a "wall" at the right.

    Name:  Elisha 01.jpg
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    Given that the moment is gone and with it the opportunity to pull the exposure back by half a stop, what's to be done?
    The first job in PS is to create a new layer, add a 'Levels' adjustment and darken the shirt by dragging the midtone slider. Merge the adjustment down into the new layer to fix it, rename the layer "Shirt" and drag it to the bottom of the pile.
    Name:  Elisha 02.jpg
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    Make the first layer active, create another 'Levels' adjustment layer and lighten the faces and gold shirt by dragging the 'White' slider to the left. Again, merge the adjustment down into the layer to fix it.
    Name:  Elisha 03.jpg
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    You now have two layers, one slightly lighter and one much darker. The dark one named 'Shirt' should be underneath. OK, with the top layer active, create a layer adjustment mask and, using a black brush, paint
    the white shirt away revealing the darker version from the bottom layer. You'll need to reduce the opacity of the brush at the edges of the shirt.
    Name:  Elisha 04.jpg
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    All that's left is to flatten the image and decide whether you like it or not. Here's a before and after.
    Name:  Elisha 05.jpg
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Size:  1.17 MB

  3. #3
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    great post peter. what do you mean by paint it black ?
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  4. #4
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    I second that, thanks for the tutorial. In the comparison between the shot of the two young men I think you got the order wrong.

    I think the first shot is after and the second shot is the original.

    I don't get the paint it black bit either
    Last edited by saf; 10-19-2009 at 03:36 AM.
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  5. #5
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    Thanks again for a great tutorial. I will try to copy the steps and see how I do.

    Frank
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    http://www.flickr.com/photos/22083244@N06/

    http://s305.photobucket.com/albums/nn219/sparkie1263/

  6. #6
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    He's using a layer mask .
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  7. #7
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    Thanks, guys. Quite right Saf and dr4gon also.
    OK, I wasn't too clear on 'paint it black' so here's clarification.

    In this pic I've already created the 'Shirt' layer and dragged it below the original 'image' layer.
    Create the Adjustment layer and 'Clip' it to the layer below as shown. The control automatically creates a Layer Mask. You may not have the same buttons in earlier versions of PS but the control is available under the 'Layer' Menu.
    I've moved the 'white' slider to the left (about 221) to lighten the Image layer and at this point you could also, with the Mask active, paint the teeth with Black (coming to this in a minute) because they are now a bit too white.
    Name:  Levels 01.jpg
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    OK, having merged down the adjustment layer into the image layer we are now ready to add that layer mask.
    Name:  Levels 02.jpg
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    Select a soft brush and set the colour to Black, with the layer mask active (click on it) you can now paint on the shirt. Because you're using a 'Mask', the action of painting erases the top layer to reveal the darker shirt on the underneath layer, however, the process is non destructive because you're just masking the area being worked on and it's reversible. Reduce the brush size or opacity to get the edges right. If you make a mistake, just change the brush colour to white and you can reverse the process restoring the top layer until you get it right.
    Name:  Levels 03.jpg
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    Hope this makes it clear.

  8. #8
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    Hmm just noticed this thread now.

    Wouldn't it be easier to use the magic wand or selection tool and select the white shirt since it is such a high contrast anyway and drop the exposure on it rather than create layers?

    I know layers will be ideal for tricky situations but in this case, the contrast of the shirt is high enough for the selection to work with very little selection correction!
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  9. #9
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    Elisha, I apologise again for mangling your image, it just happened to be there at the time, no disrespect intended.

    In this case, apart from toning down and bringing out the detail in the white shirt, I wanted to restore a bit more colour into the shirt on the left. I feel that the method I describe is best but, if you feel a selection mask is a better choice, then that's OK too, there's usually more than one way of skinning a cat. You could always do a little tutorial detailing your method.

  10. #10
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    No problem at all.

    Anyway here's how I reduced the exposure on his shirt...



    I think uploading to Photobucket instead of Flickr may have also degraded the quality a little.

    I think the gold shirt is also effecting the colour of his face
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