Here is a picture of my mother at age 86. She was on some medication that wrecked havoc with her skin, producing may red discolored areas.
Illustration 1 Original image
Illustration 2 shows the result of only using the red blemish removal technique. There is still healing/cloning work to do, but I am 80% of the way there. Note the skin is much more evenly colored.
Illustration 2 Result of using this technique. No other work done.
Make a copy layer of the image.
Make a snapshot and call it Start.
We are now going to take a precautionary step to deal with the undesired results of the healing brush when you get close to an area of a different color. The healing brush will sample this undesired color and include it in its calculations giving an undesired color cast.
For example, if I try to heal the lower left cheek near the edge, the green background will bleed into my healing.
One way to handle this, is to make a selection with the Magnetic Lasso to separate the green area from the skin. Use a feather of about 1 so it blends.
Illustration 3 show the effect of the bleeding.
Illustration 3 Healing bleed at edge of high contrast area
Illustration 4 show a quick selection I made of the face that reduces problems of bleeding.
Illustration 4 Selection of face to heal in to avoid bleeding at the edges
Now the healing is confined to the selection area and when you get to the edge the background colors will not bleed into the face. It may be necessary to blur the edge of the selection where healing was done if the feathering was insufficient and the color contrast high. This is quickly done and looks natural.
We have taken care of the edges of the face but it is still possible that we will get too close to features in the face which will undesirably bleed. To cover ourselves so that we can recover gracefully do the following:
Gaussian blur the image so that the skin color if fairly uniformly blurred. Illustration 5.
Illustration 5 Blur for uniform skin tone colors
Make a snapshot and call it Blur. Then in the History pallet, click on the Start snapshot and set the history paint marker on the Blur snapshot. The image will be back to its sharp self and when the history brush is used it will sample from the Blur snapshot. See Illustration 6.
Illustration 6 Setting snapshots for recovery net
4. Now we are ready to proceed with the technique proper. If you examine the channels you will see the the red blemishes do not show in the red channel while they do in the other channels. Set the red channel active, Illustration 7.
Illustration 7 The red channel active
5. Go to Edit->Define Pattern. You will get this dialog, Illustration 8. The pattern is of the red channel. Click OK to accept the pattern. It will be added to your patterns at the end of the list.
Illustration 8 Defining new pattern of red channel
6. Activate the Healing brush and set the sampling to Pattern. Click on the down arrow of the pattern icon to bring up the pattern dialog. Select your pattern, which should be the last pattern in the list. Illustration 9.
Important! Be sure the Aligned option is checked , not shown correctly in Illustration 9. If you don't, you will get ugly black smudges instead of removing the blemish.
Illustration 9 Setting up healing brush
7. Your original image is active. Use the healing brush and paint over the red blemishes and red discolored areas. Illustration 10.
Illustration 10 Healing brush in action, note white 'trail'. If black you forgot to set Aligned!
Illustrations 11 and 12 show the blemish before and after. Quite an improvement. Note the texture of the skin is intact.
Illustrations 11 and 12 Before and after. One swipe of healing brush
8. I have deliberately healed an area which will cause bleeding in order to show you how to recover. Illustration 13.
Illustration 13 Healing too close to edge area without precautions
Bad technigue, problems ahead.
Illustration 14 Green area on cheek edge
Result of bad technique, color bleeding.
Say this occurs and you could not easily avoid it by using a selection. Here is the fix. Make a new snapshot. Your History brush source should have been set to the Blur snapshot in step 3. Activate the History brush and set the blending mode to Color. Illustration 15.
Illustration 15 Art History brush
Now brush over the green discolored area and watch the discolorization disappear. Illustrations 16 and 17.
Of course this does not look good because I should have never healed this area in the first place, no red blemishes. But it was just to illustrate how to restore the color with the History brush.
I had retouched this image before I learned of this red blemish removal technique and I ran into difficulties with the blemish being removed but leaving areas of red behind. The image was then difficult to blend and I did not get good results.
You can see from Illustration 2, that the difficult red areas have been greatly reduced. I am at the point in Illustration 2 that I can proceed with normal healing and cloning without encountering color difficulties.
One big advantage is that you do not have to be precise with the healing brush. Since it only effects the red areas you can take bigger strokes with a larger brush. Also, you do not have to keep resampling.
You may need to do some slight normal healing on some of the red blemishes as they may have not been entirely red and the residual non-red color may show some of the blemish. Also if a blemish is not red, this technique will have no effect on it and it will have to be fixed by normal means.
This tutorial was based on a tutorial by Suzette Allen, CPP, Cr.Photog., F-PPC, S-PPC and appeared on Smartshooters.com. The main focus in her tutorial was the removal of moire, which this technique may be useful for. The red blemish removal was more of an afterthought to the main tutorial. Since I run into many more red blemished portraits than I do moire, I expanded that portion of her tutorial with my own examples and in my own words.