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Photo Restoration Repairing damaged photos

Histograms

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  #11  
Old 01-04-2002, 07:26 AM
Doug Nelson's Avatar
Doug Nelson Doug Nelson is offline
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As a test, I made up an under 100k jpg of a typical pre-restoration image. I made a histogram of that jpg. Then I uploaded the image jpg and viewed it. Then I saved it (not via copy) and ran another histogram. Attached are my results.
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File Type: jpg histfinal.jpg (26.4 KB, 41 views)
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  #12  
Old 01-04-2002, 07:33 AM
Sally Sally is offline
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What a mystery.

Do you have mac or pc?

It's 9.30pm here what time is it there?
Are you up all night?

Sally
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  #13  
Old 01-04-2002, 07:38 AM
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I use a PC, though I can't imagine how that could make a difference. There is no mechanism to change the file during or after uploading, or during downloading. If anything did get changed, the file would be corrupted and unviewable. It's a straight binary transfer.

It's about 7:30am here. I keep "irregular" hours
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  #14  
Old 01-04-2002, 09:58 AM
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DJ Dubovsky DJ Dubovsky is offline
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We have a real mystery here Sally. Actually the histogram that is shown on the second example shouldn't have much of an image left to view with all the holes in it, I would think.
DJ
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  #15  
Old 01-04-2002, 10:52 AM
john_opitz john_opitz is offline
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What DJ said is true. That's why I don't rely on historgrams anymore. If I want to see what's going on in the image. I look in the channels itself. Being a curve user only. A lot of people that use levels that go to using curves would like to see a historgram with curves, like in using levels. But really, I would not worry, because what you see on the screen is what you see on the downloaded image is what counts(as in the downloaded images). I have that Dan Margulis attitude. Do you want good looking images or good looking historgrams. Even if your not into Dan Margulis, Katrin Eismann has it in her book as an example: page 47 and 48. The before and after images, the historgrams (one in 8 bit and the other in 16 bit) are the same. After changes done to it. The images look the same in 8 and 16 bit, but the historgrams are different.
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  #16  
Old 01-04-2002, 01:09 PM
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kaulike kaulike is offline
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Sally,

This looks like JPG compression to me---throwing out data that is not needed to maintain visual coherency. Are you sure you aren't comparing the histograms from your original file and the post-compression JPG?

What's the file size difference between the JPG you create and the one you download?

(BTW, that's a fantastic restoration, I follow all your posts with a sense of urgency)
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  #17  
Old 01-04-2002, 06:01 PM
Sally Sally is offline
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Histogram mystery solved

Thank you every one for trying to help me unravel this mystery. You kept asking me questions which made ma keep going back over what I had done.

I was certainly taking the histogram from the compressed image before I sent it and comparing it to the image I downloaded. There was so much tone drop out I just couldn’t work with the images.

Finally I’ve worked out what I was doing. Because I can’t sit at all I work while standing at the computer and that needs to be for short periods. I.e. I save my work and come back to it many times. A bad thing to do with JPEG.

What I was doing was saving in bitmap because that was the only option available. I now find I can save in JPEG, open in PhotoShop and save as TIFF. The problem was accruing when I saved as bitmap.

Thanks for the information on curves but I just can’t get the hang of them. I live on a farm miles from anywhere I couldn’t go to Photoshop classes if they even existed. At 63 my learning curve is pretty lousy!!!!

Thanks all, you made me find out what I was doing wrong.

Sally
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  #18  
Old 01-04-2002, 06:11 PM
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For someone whose learning curve is "lousy", your knowledge base is pretty fantastic. If you don't use curves it is apparent to me that you don't need them. Keep up the good work!
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  #19  
Old 01-04-2002, 08:55 PM
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CJ Swartz CJ Swartz is offline
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Sally, I quite agree with Kaulike -- your experience and knowledge as a retoucher and your current level of knowledge of Photoshop translate into excellence in your work -- whether you know a particular method or not. The end result is what counts.

If there are any techniques that would speed up your work, since you have to stand to work, I guess those would be helpful to learn. I avoided learning keystroke shortcuts for years, but have to admit that they do save time. Curves continue to be a problem for me -- I can screw an image up faster using curves than any other technique -- but I'm gonna learn to use them someday! :p
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  #20  
Old 01-04-2002, 11:14 PM
Sally Sally is offline
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Thank you kaulike and CJ for your kind words.

I have been a retoucher/restoration artist for about 20 years. I have the “eye” already. It’s a matter of using what I know with new tools. Mostly rubber stamp and some very light airbrushing.

I did find learning PhotoShop hard to begin with and didn’t bother to learn the key strokes, I feel that was a good idea. I’m now gradually introducing them.

I’m now living on a retirement pension, but just love using Photoshop. My favourite pastime is restoration. I get a little work from a camera store.

Now I know how to down load photos without tone loss, I can do a challenge when I get an urge to practice.

Cheers Sally
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