Join Taz Tally for an in-depth discussion in this video No such thing as color images, part of Learning Photoshop Color Correction.
All right, in this movie I'd like to talk about the concept that there's really no such thing as capturing and editing color. I'm going to prove to you that when you capture an image and you work on it actually in Photoshop that you're not actually working in color. And this is not just some pedantic academic point I'm trying to make. Is if you understand what you're actually correcting it's going to make color correction so much easier for you. All right, so my first goal here, my first challenge is to convince you that this is not a color image. Let's see if I can do that. I'm going to go on to the window and I'm going to bring up something that's going to help me convince you about this.
I'm going to go to the Channels panel. And the Channels panel contains what we call the building block channels of an image. When you open up just any image in Photoshop, in this case an RGB image. You can see this is an RGB image because it says RGB right up top there. And this shows us how this image is actually constructed and built. Now, in a previous movie we discussed the concept, and I'd like to zoom in here, that the basic constructional building blocks of this image are pixels, square pixel bricks as we refer to them. All right? Kind of like a pixel brick wall. But this image is not just constructed, this RGB image is not constructed out of just one channel but in fact this image is constructed out of three channels, of, let's take a look, let's go back to 100% and let's look at each of these three channels in a row.
Red, green and blue. Now I'm not sure what you're looking at on your screen but I don't see any color here, red, green, and blue. Now these are labeled red, green, and blue sure enough, but they're not red, green, and blue at all, are they. We don't get the color until we actually click on the RGB. And this is a fundamental underlying concept to understanding how digital images work. You've probably heard the word digital used in a lot of different contexts. When you break down the real fundamental word digital it refers to zeros and ones. Anything that is a digital file or a digital element or a digital system is broken down ultimately into just to what we call bits, zeros and one.
To bits of information. And everything is assigned and built up out of those two bits. In the case of an RGB color image, when we look at the red channel, all we see is greyscale values. And when we zoom in on these pixels all we see is gray-scale pixels, similarly, on a green, and on the blue channel, we see gray-scale pixels as well. And notice as we move from one channel to the other, all right, the value of the gray-scale pixels changes, All right? So if we look at that pixel right there, right underneath, put one right under the cross there and we move from one channel to the other, all right, from the red channel to the green channel to the blue channel.
Notice how the gray scale values change. Look down at this portion of the image, do the same thing. Red, green, and blue. The gray scale values change as you move from one value to another. So what happens is, when you capture an image, your camera actually separates the light into three individual channels. One through a red filter, one through a green filter, and one through a blue filter. And that's what's actually saved onto your camera card, and when you open it up in Photoshop, those are the actual building blocks of the image. So where does the RGB come in? Right here, it's the take home message. All color is created by output devices. There is no color on your camera, there is no color on your computer.
So, take your camera back, and demand a refund of at least 60%, because you're only getting gray scale, you're not getting any color. But think about this! If you ever notice that the color on your screen looks different than the color off your printer? Unless you're completely color manic that's going to be true. Why? Because you're taking the same grayscale pixels and we're painting in them with different things. RGB, right, on a monitor on a glass monitor versus say cyan, magenta, yellow, and black inks on a piece of paper. Different colorants, different substrates. It's amazing they look anything alike at all never mind completely match. All right, so our goal here, and hopefully I convinced you that this is really just a sandwich of three grey scale channels.
Our goal is whenever we adjust a color image, what we really adjusting is going to be the grey scale values on those three individual channels. You get the grey scale value right, the color's going to be right. So that's it, it's no such thing as color on a camera or computer. You only get it on output devices.
- What is color correction?
- Comparing RGB and CMYK color modes
- Using grayscales and neutrals for color correction
- Understanding pixels and bit depth
- Evaluating and correcting images with histograms
- Using nondestructive editing tools
- Removing a color cast
- Performing curve corrections in Camera Raw
- Affecting creative adjustments
- Retouching an image
- Sharpening images
- Preparing for print and web use