A Quick and Easy Way to Fix Color Cast in Adobe Photoshop
Adobe defines color cast as the following: A color cast is an unwanted tint in the image due to the lighting, the white balance of the video camera, or the type of film stock used given the lighting conditions during the shoot.
That is, actually, a pretty good explanation as to why a picture looks too orange, or too blue, etc.
It is not uncommon to take a picture and it’s just awash with a color cast. I find that usually this happens inside, in low light conditions, with the camera settings set to auto. But it can happen in so many other situations also.
Case in point. The wife and I also run a food blog (http://www.dontsweattherecipe.com) which has been up for about a year now. When we started we didn’t know anything about photography. We had a Canon Rebel XSI and my wife’s ability to make good food, that’s it. Most of our earliest recipe posts, to this day, contain some pretty crappy pictures because of poor lighting. With a recently upgraded lighting solution and some new found knowledge of Photoshop I set about to fix these pictures.
I have tried several methods and I would like to share my way of dealing with this in the quickest way possible. After going through this tutorial, you may expand on it making the picture even better, but when I need quickness and best results, this is what I do.
Shown below is the picture I am going to work on. It is an image from my wife’s homemade pizza dough. Yes, she’s Italian. Yes, it rocks!
If you like, you can download this picture and take into Photoshop, and give it a go.
Pretty nasty, huh? You can tell right away that this picture is way to warm. Remember that images are made up RED, GREEN, and BLUE. The lack of one will bring about some strange looks. I know right away that this picture is sorely lacking in some blue tints, but let’s take a look in Photoshop.
Yup, with my info palette up and using my eyedropper tool, I can tell right away that there is a total lack of blue all over this picture. As I move it around, blue is so much lower than the other values that I know, even without looking at the pic, that I have a problem.
A quick note on color and RGB values for those that don’t already know. RGB values go from 0-255 for each aspect of RGB.
A pure white would have an RGB value of 255,255,255
A pure black would have an RGB value of 0,0,0
A pure grey color would have an RGB value of 128,128,128
Also keep in mind that these values also have terms associated with them such as Highlights, Midtones, and Shadow
Without getting away from myself, let’s fix this thing.
Press Command M and bring up the Curves palette. Select the checkbox labelled ‘Show Clipping’.
Begin to slide the white tick mark right above the checkbox towards the left while watching your image. What you are looking for is a white area to appear. You want to keep sliding it until you see white somewhere in the image.
You can see above that I really needed to slide over a lot before I started seeing white on the outside of the pizza. Next, we want to capture that color value, this will be what we tell Photoshop what is really white, which will in turn fix everything else (for our purposes).
Holding shift down, click the white area. It may help to have your info panel up as well. If you have your info panel up, as you move the eyedropper over the white area you should be reading 255,255,255, which is true white. If you haven’t already, hold down shift and click on that color.
Hit Cancel on the Curves dialog box.
Bring up your info panel and you will see a new set of numbers. This is the captured color that you just got with the eyedropper.
As I mentioned earlier, true white is supposed to be 255,255,255. This is not that, is it. So, let’s adjust this.
Create a Curves adjustment layer. You can do that from the Layer menu or click the half filled circle icon at the bottom of your layers palette. Show the properties of your curves adjustment layer, if it’s not up. You should be looking at something similar to this.
You can notice straight away looking at the RGB channel we’re missing some information in the highlight area, do you see that gap on the right side there? This is some missing image information that we’re going to deal with. We are going to adjust each color channel, RED GREEN and BLUE, one at a time. Right above the graph is a drop down containing the color channels. Select the RED channel and drag the white tick mark at the bottom of the graph to the left until the R: value in the info panel reads 240-245. Yes, the picture got even worse. We’re not done yet.
Repeat the same step but for the GREEN channel and then the BLUE channel. You want each R: G: B: to be between 240-245 or so. Also, they should be as close together as you can get them. You should end up with something like this.
As you can see this already looks tons better. The color cast is gone. Now, this is a quick and dirty method to bring about very good results very quickly.
After this I usually throw on another curves adjustment layer and tweak the highlights and shadows. I could even throw on a Vibrance adjustment layer to bring out a bit more saturation. But this technique should get you to where you want to get to.
A note on why 240-245 versus 255. If you use the pure white value that is exactly what you’re going to end up with. This is pure white, blowing out any detail that was there. Keeping it a bit lower will keep those details in place keeping the picture from being way too over exposed.
Here is a video going over these steps.
Well, I hope this helps somebody. Take care!
Oh yeah, almost forgot. Here’s the link to a very good homemade pizza crust!