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Channel Replacement

Started by schen, May 31, 2008, 03:46:14 PM

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I recently restored a photo using a technique from Katrin Eismann's "Restoration & Retouch" book successfully.  I would like to share it with you.

As always, our beloved distributors have the greatest talent of hiding the most difficult damages in the thumbnails when we pick the photos to restore. 

I just finished a difficult one and was looking for an easy one to catch my breath.  This one looked innocent enough.  I thought I only had to do a little level and color adjustments then clean up the minor damages around the boarder.  It would be ready to go home.

The original

When I opened the hi-res download, to my horror, there were numerous orange spots on her hair and other places.  The original was a 12x18, so the area I shown below actually presents an area of about 4"x5.3".  At that size, there was no way to hide the damages.

An selected area showing the orange spots

I checked the RGB channels.  Lo and behold, the blue channel contained all these dark spots corresponding the the orange spot damages.  Fortunately, they only existed in the blue channel.

The selected area in blue channel

My first instinct was to repair the spots in the blue channel. 

It proved to be difficult and tedious to remove the spots and still retain the texture of her hair.  After an hour of work, I managed to clean an area no more than two square inches.  I knew I needed to look into some other methods.  I vaguely remembered Katrin's book had a section about restoring a photo with the blue channel completely faded.  She replaced the blue channel with the Lightness channel in Lab mode.

I checked the Lightness channel and luckily, it not only had much much fewer spots, it had approximately the same appearance as the blue channel. 

The selected area in Lightness channel of Lab mode

The steps of replacing the blue channel with the lightness channel:

1. Open the original image file

2. Select Image>Mode>Lab color

3. Select the Channels tab and click on the Lightness channel to activate it

4. Select Select>All then Edit>Copy

5. Select the History tab and click on the Open before the Lab Color entry to discard the Lab Color mode and return to RGB color mode

6. Select the Channels tab and click on the Blue channel to activate it

7. Select Edit>Paste to replace the blue channel with the Lightness channel

The selected area with the blue channel replaced by the lightness channel

As you see in the image above, the orange spots were gone and the hair looked much better.  But the side effect of replacing the blue channel with lightness channel was that the true blue areas now appeared green as below:

The original with the blue channel replaced by the lightness channel

These side effects may be corrected by selecting the areas that should be blue and do color balance by pulling the Yellow-Blue slider to the Blue.

Color adjust the blue jeans after blue channel replacement

The complete restoration

Shujen Chen
Windows 10, Photoshop CS6


I have just the picture to try that on Shujen!  Thank you for sharing!


That was slick! Thanks!!! Bookmarks...



I had to smile when I read about how your easy photo turned out to have a few "glitches," as we in the distribution end like to call them. If the thumbnails in the gallery were a true indication of the damage, do you really think that we would get as many takers? Your horror story was making me giddy to think we had pulled this off successfully. Then I sobered up quickly when I realized that you were going to provide a tutorial to help your fellow volunteers. What kind of deal is this? I hate to admit it, but your tutorial was great!


PS When you get done with one, I have a really easy photo  for you with minimal damage.  >:D
"carpe diem"

Margie Hayes
OPR President
[email protected]


Quote from: MarCat on May 31, 2008, 05:10:11 PM
When you get done with one, I have a really easy photo  for you with minimal damage.

Yeah, right.   ;D
Shujen Chen
Windows 10, Photoshop CS6


Dave Ellis
OPR Founder
[email protected]


Thanks Shujen, a really helpful tute and a great result :up2:



Thanks Shujen, just finished one with similar problems so am adding your description to the file



Shujen, I tried this process awhile back, and was not to successful. I think I will give it another shot though. Thanks for the info.  :wow:
David J. Davis

Windows 10 Pro, Photoshop CC 2018, Intel i7 4770K 3.5GHZ, Nivida GeForce GTX 1070


Chen, I also want to thank you for an excellent tutorial, your instructions are so clear!  (that must the teacher in you!)
I tried it already and love the result.  I also used the "selective color" adjustment sliders after I pasted the Lightness channel in the Blue channel. (David, you might find them helpful if the results of this method don't do the trick on any particular photo.)

It is wonderful to be reminded of all that is possible looking/working in the separate channels.  Up till now I used the channels mostly for diagnosis or lost information retrieval, now I also work in(in?) them.

Your restoration looks beautiful and I think it is so thoughtful of you to touch the ladies nail polish while you were at it!



Hannie Scheltema
Distribution Coordinator
[email protected]


Thanks Schen,

That was an excellent tutorial - I love it how you explained it step by step with pictures included.  I had a similar case a while back and wish that I would have known about the method that you described.