Help on colour burn

Malte

What is it really? Overexposure of a single colour? How do you get rid of it? Are there even pixels to be salvaged in there?



Thanks for any input!

Malte

irenelucier

Malte wrote:

What is it really? Overexposure of a single colour? How do you get rid of it? Are there even pixels to be salvaged in there?

Thanks for any input!

Malte

Nice capture. Not sure what you mean by color burn, but looking at the levels the blue and green were bunched up while the red had a nice spread. Used curves to set the black boint on blue and green channels, then another another curves adjustment on RBG to brighten it up just a bit.

I was trying to balance the red to the blue and green. Maybe someone else can contribute a more effective way. In my attmpt the blue and green are stonger, and the red is less pervasive in certain areas like the eye, but it still seems unbalanced to me.

Yours:


Mine:

Malte

Thank you Irene! I like your improvements, but what I'm talking about is the loss of detail in the orange on the top of his head. I was unclear, sorry.

Malte

jfriend

Not much you can do unless you have a RAW file

Malte wrote:

What is it really? Overexposure of a single colour? How do you get rid of it? Are there even pixels to be salvaged in there?

The problem is that, in the top of the head area, the red channel is completely blown (the values are all pegged at or near 255) and it's the dominant color so you lose most detail. If, in Photoshop, you make a selection of the area on the top of the head and then look at the histogram, you can see what the red channel is like in that area. In looking at that histogram (see below), you will see that all the red pixels are crammed up to the top of the histogram. Since a variation in tonal value is needed to show detail, you lose detail.

I tried a few things to attempt a rescue, but nothing was successful. I tried, a highlight adjustment on the red channel using shadow/highlight to see what could be recovered. I tried a steep curve in the highlights to try to stretch out the red tones over a broader range. Nothing worked.

If you shot in RAW and have the RAW image, that would be your best hope. Turn the exposure way down in the RAW editor to let it do it's best job at trying to pull detail in those highlights. Then, while the rest of the image is underexposed, apply a curve(s) to raise the mid-tones, but while trying to avoid messing up the overly red areas. This is an example of the type of image that you might be able to do more of a rescue on if you shoot RAW.

In the future, any subject with lots of red (red flowers of any kind commonly have this problem too) is prone to overexposure in the red channel due to the way the camera meters. If I'm shooting a predominantly red subject, I know that I have to underexpose the image in order to preserve the detail in the red channel. A camera with actual RGB histograms can be very helpful.

Here's the histogram of just the top of the head. You can see there's just no detail in the red channel.

jfriend

The other option
After saying there isn't much you can do in my previous post, there is another tactic that can be used: cloning/copying a good area of feathers into the blown area.

Here's one attempt at that below. I copied an area from below the eye to a new layer, moved, rotated and stretched it a bit to get the direction of feathers to line up and make it big enough, then blended the edges with a mask. What do you think?



And your original:

Malte

jfriend wrote:

...If you shot in RAW and have the RAW image, that would be your best hope. Turn the exposure way down in the RAW editor to let it do it's best job at trying to pull detail in those highlights. Then, while the rest of the image is underexposed, apply a curve(s) to raise the mid-tones, but while trying to avoid messing up the overly red areas. This is an example of the type of image that you might be able to do more of a rescue on if you shoot RAW...

Thank you so much for all your help jfriend! I'm trying out the raw exposure method now, will get back when I have some results.

The file in raw and tiff, if you want to give it a whirl:

http://malte.typepad.com/CRW_4336.CRW
http://malte.typepad.com/CRW_4336_RT8.TIF

Thanks again!

Malte

Malte

A first stab.

Before:


After:


I think I see atleast a tad more detail, but it's hard to tell.

Malte

edgework

Seeing as how skin tones are basically Red, seems like Dan Margulis' luminosity blend of the green plate should achieve an increase in detail, and it does. It's a little darker than the original, but that's because very little of the added detail is actually lighter than the base color. I kept the green layer into LAB, where luminosity works better, and restricted the effect mostly to reds with blend-if sliders. Then a curve to lighten.

Duffy Pratt

I applied the green channel (inverted) into the red channel in overlay mode at something like 80%. This was a quick and dirty way to bring some detail into the red without doing too much channel rebuilding. (There are probably better, slower ways to do this).

Then I did a pretty strong Shadow Highlights move on the red channel to get whatever detail I could out of the red highlights. (Again, there are better, slower ways to do this. See the last channels of Margulis' Professional Photoshop 5th edition).

Then a quick trip to LAB to limit the changes above to where the background channel was Strongly A positive, with Blend if sliders. While in LAB, I set a white point and boosted the A channel back a little to get the reds closer to where they started.

I'm sure there are better ways to do this. But what I did was quick (a few minutes) and it shows the direction to go in. The way to achieve this is definitely by doing some plate blending to rebuild the shot red channel. And I think the best way to go about that might be by working with the cyan channel in CMYK.

Duffy