Got the ACR shadow blues

One thing that I've noticed in my digital processing is how routine it is to get strong blue casts in shadows, especially when there's shaded water. I expect that this is a digital equivalent to the color cast choices in film and wonder how much of it is how Adobe adds saturation when luminosity is reduced. I've recently taken to using a hue/saturation layer in PS to reduce this cast, but am wondering what others think about it and how (or if) they adjust it in post processing. Oh yeah, I usually shoot my 5D on auto white balance.

Mark, it's easy to check if your image has an overall blue cast.

Before making any adjustments, create a copy of your background layer in PS. Next, go to Filter>Blur>Average. The image will change to a solid color. This color is the color cast in your image. To remove the cast, do the following.

Create a levels or curves adjustment layer above the blur layer. Click the Grey eyedropper button. Next, position the eyedropper anywhere in the blurred image and click. The blur color will become a grey. Now, turn off the blur layer. The color cast should be removed.

Note that if an image has a strong blue cast (for example) your image may now be a too yellow. If this is the case, you can select the blue channel in the levels or curves you already created in order to put a little blue back in. I use this technique quite often and find that it works very well, and is easy to do.

If your shadows are still too blue, you can select the blue channel in a levels or curves layer and adjust the blue in the low values. Another option is to use Tony Kuyper's Luminosity Masks. If you have them, create a Darks or Shadow Darks Luminosity mask on a levels or curves adjustment layer. You can easily adjust the blue channel to correct the color balance of the shadows. I highly recommend Tony's Masks.

I hope this helps.

--P

Blue shadows are the way light really is and it is more evident when the shaded area includes water since the water reflects sky. You also run into mixed white balance if you are shooting indoors with artificial light but the image includes windows with daylight. Shooting on auto white balance will give you dominant color temperature or a compromise one where where one is not clearly dominant. You could try shooting two frames, one for the shaded area and another for the sunlit area and then combine them using a layer mask on one to 'paint in' the appropriate areas of the other frame. If you wanted to a get really detailed mask you might try making the mask from the appropriate color channel. Working in Lightroom with only one frame I'd shoot for the are that was more than half the image and then paint or use the graduated tool to alter the hue of the other part(s). Don't try to totally correct the difference if you are going for realism. Our eyes tend to downplay the difference in hue between shadow and sunlit areas but we do see them. Totally removing the blue cast from shadows would look unnatural.

Here's another way way to get rid of a cast, if you have a bright area in the photo. It takes less than a minute to do.

Duplicate the bg layer. Then open a Threshold layer. Move the Threshold slider all the way to the right and then slowly back to the left until the layer starts to show some white. Then use the Color Sampler tool to click on the first white area that is revealed. This is the lightest part of your photo. Then do the same thing with the Threshold slider all the way to the left and then slowly back until the first black is revealed. Click on it with the Color Sampler tool.

You have now created two "Points" that will have their rgb values displayed on the Info pallet.

Delete the Threshold layer. We don't need it any more.

Open Levels or Curves and then click the Highlights dropper in the Levels/Curves box, and click the brightest Point in your image on the dup layer. Then click the Shadows dropper and click the darkest Point in your image.

You've now removed the cast.

Several options with this approach: Sometimes I only use the the Highlights dropper, because I don't like what the Shadows dropper has done. Sometimes I go completely with the duplicated layer. Sometimes I mask portions of it and use a combination of the bg layer ( the one with the cast) and the duplicated (cast-corrected) layer. Sometimes I adjust the opacity.

Again, let me mention this only works if you have a strong highlights section in your image. Otherwise, it's too much.

Hope this helps. If it's confusing, shoot me an email with your phone and I'll call you. I have free long distance!

Thanks for the fast responses...lots to think about. I tried both Preston's and Lance's suggestions and they result in substantial improvement (at least to me). I'm going to post the results. First, the original.

Now for the "Birdwell" correction.

And finally, the "Warley" correction. BTW, I also tried changing the color temperature in LR/ACR and found that adding 1000 to the color temp also gave a similar result at least for this image. However, that's a by guess and by golly approach. I much prefer a measurement based method. It's also worth noting that the color changes are much more noticeable in PS or LR than in these JPGs.

Some comments:

Before making any adjustments, create a copy of your background layer in PS. Next, go to Filter>Blur>Average. The image will change to a solid color. This color is the color cast in your image.

This is the color cast only if the image has "average" color to begin with. If you start with a close up of a red firetruck your averaged layer will be some shade of red and not a color cast.

Lance Warley's method is essentially a manual multi step process of what "auto levels" does. Auto Levels finds the whites and blackest points and assigns the values of the white and black eyedroppers to them, and this remaps all the pixels.

It's also worth noting that the color changes are much more noticeable in PS or LR than in these JPGs.

Why would that be? This sounds like you are experiencing a color shift from working in Adobe RGB in PS or LR and not converting to sRGB when you save a jpeg.

Why would that be?

If the blues that look over-saturated to Mark are outside the bounds of sRGB, even a correct conversion to sRGB will change the color. And that could serve to lessen the amount of change seen here due to processing. Perhaps that's what's happening.

"This is the color cast only if the image has "average" color to begin with. If you start with a close up of a red firetruck your averaged layer will be some shade of red and not a color cast."

Richard is quite correct. My technique is for images that have 'average' color to begin with; such as landscapes.

If you do have an image that is predominately one color, you can create a levels or curves adjustment layer, click the 'grey point' button and then click on a spot in your image that is very nearly grey (the color numbers are nearly equal to one another). This may, or may not, remove a color cast, and you might need to tweak the individual channels to get the right color balance.

I don't use ACR or Lightroom, so I can't help, there. I hope you get this sorted out, Mark.

--P

Mark there are many different techniques similar to the one outlined by Preston,

Check out this idea too. I stumbled across it a few weeks ago and really like it.

Best wish,

Carol

That method could be problematic Carol.

The problem I see is that it isn't actually identifying what in the image should be neutral gray. Instead, that process will find the areas of your un-balanced image that are currently closest to neutral gray - before correction. It's completely possible that the image areas closest to neutral grey in your current image shouldn't be neutral gray in your final image.

Although, that method probably does work well a lot of the time, I'd guess especially if your color balance is already close to begin with. That doesn't mean it will work every time - especially not if trying to set larger changes.

Richard, I think the reasons that the differences are harder to see in the posts are that sRGB is a more limited color space than the prophoto RGB that I use, there's also the jpg compression, and finally I'm viewing on a 27" monitor, which makes details easier to see. In the posts above, I can see the change between the original and the two corrected versions, but see very little difference between the two corrections. On my monitor, there are also clear differences between the two corrected versions. I like both of the corrections better than the original, which to me seems way too blue in the water and in the reflective rock faces.

I expect that at least part of this is personal preference on my part, but I sure notice the saturation increase when I increase contrast or set the black point and often the blues seem overdone.

"I expect that at least part of this is personal preference on my part, but I sure notice the saturation increase when I increase contrast or set the black point and often the blues seem overdone."

It's not just you. Saturation does indeed increase when using Levels or Curves to set contrast. Try changing the adjustment layer blend mode from Normal to Luminosity after you make your changes and you'll be surprised at the difference when the contrast adjustment affects only the light values instead of the ]light and color values. As a side benefit, image pixels are slightly less damaged when using the Luminosity blend mode.