If you can't see the color cast...

that other people see, what do you do? Is there any help for that? Thank you.

Barbara, below is a post I posted some time back that allows you to "see" and control whatever color cast happens to be in your images. This takes the subjectivity out of it. Keep in mind that color cast is not necessarily a bad thing though, but if you want to adjust the amount of cast, this method will easily and quickly allow you to do it.

I saw this tip the other day on another forum and thought I'd post it here. The tip came from Charles Glatzer. This is very easy to learn, and takes the subjectivity out of removing casts. The only "addition" I might add would be to experiment with the final step (#6). Don't just automatically go to 50%, but play around a little with it.

1. Duplicate the background layer (Ctrl J)
2. Select the duplicate bkgd layer
3. Filter > Blur > Average (produces a solid color matching the color cast)
4. Open Levels Adjustment Layer, click duplicate bkgd layer image w/ middle (gray set) eyedropper.
5. deselect layer visibility icon (eyeball) of duplicate bkgd layer
6. tweak adjustment levels layer opacity to suit taste (50% is norm)

Thank you very much, Bill. David Chauvin had given me that information in the past, but I had momentarily forgotten about using it, though I've used it successfully since he told me about it. It just bothers me a very great deal that I can't see color casts when multiple other people can, and that's something that doesn't seem to be improving.

I wouldn't worry too much about it, especially since you can use the above tip to check on and control color casts. I use this early on in my workflow just to see if I want/need to adjust anything. Many times I end up deleting it from History as I choose to not adjust anything, but it's always nice to check things out first.

Barbara,

If you use Bill's method, which I also use, be aware that if the image has a heavy color cast, the resulting image may shift to more toward the complimentary color. For example, if the image is very blue and you use Bill's method, the color may shift toward yellow. To correct this, choose Blue in the dropdown on the levels layer you created and then adjust it to remove the yellow cast. Note that you may also need to adjust the red and green channels in the same levels layer.

If needed you can also use a Selective Color adjustment layer to fine tune.

--P

I assume tihs is in response to my comments on your current post of the Palm Warbler in avian.

Note that my comment is about the color of the warbler alone and it is based on my experience of having seen hundreds-thousands of these birds in the wild over 40 years of birding.

I haven't tried this technique but I worry that it will be heavily swayed by the overwhelming greens of the setting and will force you to shift the image even farther towards magenta.

Edit:

ok - I just tried this technique and got exactly what I expected.

Averaging the duplicate layer gives a green value of 127,151,109.

Neutralizing that with a levels layer and hiding the solid green layer turns the original image even more magenta and makes the color cast on the warbler even worse.

A simple way to deal with images that have a very heavy color cast, is to adjust the Layer Opacity of the new layer, as described in Bill's original post, to taste. I use this method all the time and different images get different amounts of color correction.

Barbara,

There are a couple of aspects to this I think. One of them is what you do about color casts and techniques to reveal and adjust them; such what Bill and Preston mentioned. I too use that technique, but I would caution anyone to not rely on that for every image. Like anything else in processing, there are a gazillion ways to do things and each image should be treated individually and not blanketly apply techniques just because it's a cool technique.

But the other aspect and more towards what I think you're asking is, how do you learn to "see" a color cast? How does one know just by looking at an image if there even is a color cast. You need to know this before you can apply any technique to correct or change it. It's one thing to learn and use techniques to adjust color, contrast, etc., it's an entirely different thing to learn and understand how to see whether or not changes even need to be made.

There was a recent thread about a color test that I think can actually give you a ballpark idea how well you see colors to start with. We all have different dna, some folks have sensitivities to various colors, while others may not. Some folks are color blind to certain colors, etc., so that makes it difficult to even help or teach people to how to see a color cast to begin with.

Another factor that we all fall prey to is simply looking at our own image for long periods of time. The more you look at something the more likely you are to quit "seeing" things and eventually you think all is good. Next thing you know you show the image to someone and they immediate mention a color cast. I think this happens quite often here on NPN. I know I see and mention color a lot in my comments.

Here are a couple of tips that may help you and others in learning to "see" color casts.

1. Step away from your processing. Close an image, work on a different one and return later to the same image. As I just mentioned if you look at something too long you can quickly lose sight of any color issues (this goes for composition, slanted horizons, all that stuff.)
2. Use a technique like Bill described above. But rather than just accepting it, turn the layer off and on several times and study what is changing. By turning the layer off and on you can actually see the colors change.
3. Google the "color wheel" or color in general and learn the major colors, complimentary colors, etc. The more you understand about color, perhaps the easier it will become in recognizing it.
4. Go outside and study the colors when you're photographing or just walking around. For years I never saw color casts in the field (or looked for them for that matter.) But several years ago I started paying attention things and could actually start "seeing" color and light before I even took a picture. Walking in an aspen grove buried in a deep canyon before sunrise.... when I paid attention, I could actually learn to see the blue light present. With the absence of the direct bright and yellow light of the sun, the scene is naturally more blue (and reflected blue light from an overhead sky, etc.) and I learned to see that. Paying attention to those kind of things when you're out and about may help you when you get back in front of the computer later to process your image.
5. Lastly, as you read through comments here on NPN and someone mentions that they see a "magenta color cast," take another look at the image and see if you can see it. But remember what I said earlier, we're all different and not everyone is going to see the same color cast or intensity.

For an example, take a look at Preston's recent image of the charred tree. I know he won't mind me using his image as an example. I see a subtle, but fairly distinct magenta color cast in the mid to bright tones. And Preston and I have actually exchanged emails about this and he already knew this and saw it himself (without the feedback) and told me he fixed that in his printed version. But it confirmed to me that what I think I was seeing was also seen by Preston.

Anyway, I've rambled enough already. Hopefully this gives you some food for thought. Keep at it, you are certainly asking great questions.

Lon

Thanks, everyone. Lon, yes, it is the seeing that I'm talking about rather than the fixing. I'm going to go through your suggestions. I'll let you know what I discover.

Okay, I just took the color test, and my score was 29. My hue discrimination was lowest in the colors between green and blue and at the rightmost end past the purples, but I don't know what colors those are

In PSE 9, I use Remove Color Cast (Enhance, Color). Any thoughts? I usually sample an area of my photo that's supposed to be white. If I don't like the results, I "reset" and try another sample...and another if I have to. Sometimes I don't like any of the results and leave the photo as-is. It seems to work fairly well...for me, anyway.

I sample an area that's supposed to be bright white and another that's supposed to be dark black. If an image doesn't have bright white or dark black, it won't work.

Open a Levels or Curves layer and use the Highlights and then Shadows eye dropper to click on the bright/dark areas. This will remove the cast. If you have the Info pallet open, it will show you the values for the points where you clicked (e.g., 245, 245, 245). Then adjust opacity and mask to taste.

To find and to keep an eye on the brightest/darkest spots, open a Threshold layer, move the slider all the way to the left/right, then move it back holding Alt, and it will eventually display where the brightest/darkest spots are. Then click on them with the Color Sampler tool to set them as "points." I almost always do this. It's a good way to ensure you don't blow the highlights as you process. I try to keep the whites below 250 unless it's appropriate, like the sun.

Lon makes excellent points, Barbara. One really must train themselves to see subtle nuance in color and tone. This will take time and require a disciplined effort. As Lon points out, don't stare at an image, or a real life scene too long, since your eyes will adjust and you'll no longer see the cast.

There is one thing I will caution you about with regard to removing color casts: Use only one method. If you try to combine methods, you could run into trouble. You'll really need to experiment to see which method works best. For example, if Bill's method is not working, delete or turn off those layers and then try another method.

Lon and Harley always point out color casts in my stuff, and I'm glad that they do . Honestly, I made the web image of thecharred tree before I made a proof print. Once I saw the proof, the slight casts were visible and subsequently fixed for the final print. I am glad Lon used my image as an example because it points out subtle things that can be corrected in order to make a nice image even better.

--P

Another easy way to check for color casts is the "Variations" adjustment. I wouldn't recommend making any changes to the image with that tool but it can be very helpful for identifying color casts.

An alternative technique for balancing color is to use a levels adjustment layer. Open each channel separately using the drop down dialog that defaults to RGB. Set each slider on the right to the point where the histogram leaves the base line. Until you have all of them set it will look bad but the color cast should be pretty well neutralized when you finish with the blue channel.

Obviously this works only on images where you have a bit of space on the right of one or more of the channels. If the red, green & blue channels all go off the right side of the levels histogram it will only make the image too bright to pull the right slider in.

Another way to get rid of color cast in CS5 is Image>Adjustments>Match Color. Click on Neutralize, then adjust the fade % to tweak the changes. Like other methods, it doesn't always work, and can get really bad sometimes. I have a hard time seeing color casts also, and this method will sometimes help me to see and fix them.

Good question Barbara and a good thread. I also have trouble sometimes seeing color cast and especially in my own image when I'm processing. I can sometimes see it after I have posted it and later comeback to it so the taking a break from that image is a good start for me personally. I'll have to try the other suggestions too.

Bruce

I learned color correction using cc filters during 16 years of photo lab work. Using 2.5, 5 and 10 cc filters (cc=color correction units. 1 cc is likely not apparent to the untrained eye) we would take these gels and put them in front of the photo to see what affect they made. Photoshop used to have a color correction function showing 9 larger thumbnails of your image arranged in an array of 3 across and 3 down. The center image was your shot as it is. While the surrounding images were X units different in color in all of the majors colors: c m y r g b with the other two being variations in exposure. I don't see this tool in CS5.If you have an older version with that tool in it, playing with it will help you recognize color shifts (color casts).I rmemeber it being near the bottom of the "image" menu.

In CS5 you can open up a color correction layer for the image. To begin with correct the mid tones. put your cursor in the value field for the cyan-red slider and usee the mouse wheel to make changes. Begin with changes of about 5 units either way and watch the color, If they are both too much reduce it to 3 units each way. Then one or two each way. One of the adjustments will look best. Then do the same for magenta-green or yellow-blue. You may find that you need to go farther than 5 units but most of mine are less. Then do the same for the shadows and highlights. Over time you will be able to perceive the one unit changes and will begin to identify color casts in the scene. One important thing to note is that in reality you only need to change 2 of the sliders to bring a photo to a color balance. Just as in photo printing in the darkroom, only 2 of the colors are manipulated for a good color balance. Use of the third would cause a neutral density change (exposure, not color).

In LR the the changes are not quite the same thing. The hue slider only shifts the color toward the nearest neighbor color and not the compliment or opposite color. So it has limited use as a color correction agent. You could use the adjustment brush and add color to the masked area by using the opposite color of the color shift. Just get it from need the bottom of the color selection window. I suppose if you masked the whole image you could experiment with identifying a color cast.

There is also training the eye to see color as is mentioned above. A lot of this skill is just making your brain aware of the fact that light has color depending on how it gets to the subject. If you can look at some mountains near mid day with a clean blue sky you sould look for the blue shadows of the ridges. They are blue because the light source is not the sun but the sunlit blue sky (that is a simplistic explanation). The brain see the mountain and inserts the colors, so to speak, according to what it expects to see and not what is really there. To see what is really there you need to stop and look and observe closely until you can discriminate the blue. Its a switch in the brain you can eventually learn to turn on and off and then put to use in your shooting.

Here is a nice page regarding Color Theory and our perception of color.

--P