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Photography Question 
Michelle B. Prince
BetterPhoto Member Since: 9/16/2004
 

Using curves in photoshop


When I use the curve in photoshop to lighten up a photo I notice that the histogram looks really broken up. It is damaging the image to curve it?


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8/16/2005 4:38:57 PM

 
Laura E. OConnor
BetterPhoto Member Since: 5/12/2005
  If it's a jpeg, just about EVERYTHING you do to it will start to degrade it. If it's a LARGE jpeg, it takes a lot before you start to notice the reduction in quality. My suggestion...save the original and save your changes as a copy!


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8/16/2005 4:41:34 PM

 
Michael H. Cothran   The "broken up" histogram IS losing detail. Does your histogram have white slits running down? If so, these are areas where there was once detail, and now thrown away, never more to return.
This should not happen (to my knowledge) with ANY Adjustment Layer, including Curves.
Michael H. Cothran
www.mhcphoto.net


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8/17/2005 11:46:36 AM

 
Laura E. OConnor
BetterPhoto Member Since: 5/12/2005
  I ALWAYS happens to me, particularly when using any of the "Auto" fixes (levels, color, contrast) or the curves. When you look at it again, or look at the Levels at that point, there are TONS of while slits in the histogram. I know it won't happen when working in RAW, but in JPEG, it does. BUT, as I mentioned above, if you are working in a Large/Fine JPEG, it really doesn't show in the image until you've done A LOT of editing.


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8/17/2005 12:15:11 PM

 
Michelle B. Prince
BetterPhoto Member Since: 9/16/2004
  Michael, Yes there are white lines so I am messing up the photo. It happens when I curve an image. I have pretty big jpeg files from the large (not raw) selection on a 20D. If I am working on a copy and delete that layer does it still effect the background layer? Can I then just undo it by going back in the history with out damaging the photo. thank you so much.

Laura. I will have to shoot raw and see if this makes a difference. I don't usually shoot raw because I am not sure how to fix the images up yet.


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8/17/2005 3:24:12 PM

 
Laura E. OConnor
BetterPhoto Member Since: 5/12/2005
  Me either. I have yet to notice any real image degredation, though. I always shoot JPEG, Large, Fine and they seem to hold up fine because they're such big files. Good luck with it, let me know how it works out!


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8/17/2005 6:17:38 PM

 
Gregory LaGrange
BetterPhoto Member Since: 11/11/2003
gregorylagrange.org
  It may be better described as a loss of information rather than loss of detail. You can lighten a photo with curves without seeing detail loss when you print. It's best to use the eye drop things to set whites and blacks instead of leaving it up to auto.


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8/17/2005 7:49:25 PM

 
Laura E. OConnor
BetterPhoto Member Since: 5/12/2005
  I'm an ABSOLUTE beginner at PS and have a lot to learn. I'll have to look into that, Gregory! Thanks!


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8/17/2005 8:03:21 PM

 
Michelle B. Prince
BetterPhoto Member Since: 9/16/2004
  Gregory, do you mean to use the eye dropper when working on black and whites, or color too?


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8/18/2005 3:46:47 AM

 
Gregory LaGrange
BetterPhoto Member Since: 11/11/2003
gregorylagrange.org
  The eye drop things in the levels and curves windows for any photos. Not the eye drop in the tool bar.
A simple lightening can be done with pulling up on the middle of the line in the curves window. Although it is levels that I use if I need to set blacks and whites.


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8/18/2005 1:52:03 PM

 
Laura E. OConnor
BetterPhoto Member Since: 5/12/2005
  That's what I use, too, the levels, but I use the sliders instead of the droppers, and the curves, depending on what I think needs to be done. I normally use those instead of the Auto fixes these days because of the lack of control and the effect on the histogram those give.


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8/18/2005 2:14:04 PM

 
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