From the course: Photoshop One-on-One: Fundamentals

Identifying the color cast of a photo - Photoshop Tutorial

From the course: Photoshop One-on-One: Fundamentals

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Identifying the color cast of a photo

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- [Instructor] Now, the first step in correcting the color cast, or if you prefer, color bias, of a photograph, is to identify what that color cast or color bias is. And so, here we are looking at an underwater GoPro photo, no lights whatsoever. Your photos don't have to be underwater; I just happen to have a lot of them. And so, we can safely assume that this guy is too green. After all, I'm about 30 to 40 feet deep, and so I've lost a lot of the color spectrum. You lose the reds first, then the oranges, then the yellows, and after a while, you're left with greens and blues. But we are seeing a little orange here and there. And even if we're pretty confident this is a greenish cast, there's no sense in not checking for sure. And you can check exactly what the color cast is using the Eyedropper tool, which you can get by pressing the "i" key. And what I've done is I've created a bunch of copies of this layer for comparative purposes later on. But I also, up here at the top, have this shape layer, which is a circle, which is identifying the region that I think ought to be neutral. And when I say neutral, it should be a lightish gray. Whereas if I were to click inside there, and notice when I click and hold, I am seeing a color ring, which is showing me the old foreground color on the bottom and the new foreground color at the top. We can plainly see that that is a kind of green. All right. But to confirm for sure, what we need to do is make sure the Color panel is on screen, and if it's not, you can go to the Window menu and choose the Color command. Of course, do not choose the command if it has a check mark in front of it. And then click on the flyout menu icon in the top right corner, and switch to HSB sliders, is generally the easiest way to work. And that way, we can see our hue, saturation, and brightness values. Now, all the brightness value is doing is telling us that this is a pretty bright color, so it's somewhere in the mid-tone to highlight range. That's just fine; it's not anything we need to worry about. The hue value is telling us the base color in degrees, and I'll show you what that looks like in just a moment. And then the saturation value goes from gray, at 0%, all the way to the most highly saturated version of that specific color, at 100% percent. Now, if this were a neutral image, if it didn't have a color cast, then this saturation value would be somewhere in the zero to 10% range. Instead, it's extremely high, at 37%. That means we have a pronounced color cast. All right, let's take a look at the hue value, however. 172 degrees is very close to cyan. And so, I'll go ahead and switch over to this big color chart that I've created for you. And by the way, it measures 32 by 22 inches, in case you decide you want to print it out. And I've gone ahead and mapped out all the hue values on a circle, starting at zero degrees for red, and then going back all the way around to 360 degrees, which would once again be red. And so, the visible color spectrum, at least where hue values are concerned, ultimately forms a continuous circle. And so, notice we have the industry standard colors of red at zero degrees, yellow at 60 degrees, green at 120 degrees, cyan at 180, blue at 240, and magenta at 300 degrees. And again, these are industry standard colors, which is why I've set them in the largest type. In between, we have subjective colors. Now, I think we can all agree that 30 degrees is orange, but I'm calling 90 degrees lime, 150 degrees turquoise, and so forth. Now, around the outside, we're seeing the hundred-percent saturated versions of the colors. Toward the inside, we're seeing 0% saturation. So everything ultimately goes to gray. Our color cast is 172 degrees, which means we need to send it from this point over here, probably right about here, actually. I'll just go ahead and drag around, and you can see the hue values changing over there. So right about there is our color. And so, we need to take it in absolutely the opposite direction. And that's exactly what we will do starting in the very next movie.

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