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In this movie, I would like to discussion what scanners, and for that matter digital cameras capture and create, and hopefully at the end of this video, you will have removed some of the blackbox effect of what a scanner is and what a scanner does. And I will also give you some foundation knowledge, so you will know as you are selecting various scan modes, what you are actually going to end up with, at the end of your scan process. Okay, first step, what the scanners and digital cameras create, what's the basic building block? It's pixels. And we see the pixels here. Pixels are basically square building blocks.
I refer to them as pixel bricks and what a scanner and a digital camera does, is they construct an image out of these pixel bricks, if you will. Now depending upon the scan mode in which you are working, you can create certainly black-and- white pixels to pixel bricks. When you work in say grayscale scan mode, you capture pixels that have grayscale values or if you're working in color RGB scan mode, you can actually create "color" pixels. We are going to put that color in quotes, because as you are going to see scanners and digital cameras don't actually capture "color," more on that in just a second.
By the way, the dimensions of these pixels, the size of these pixels is all wrapped up in a linear resolution of the file which we'll talk about a little bit later. Okay, let me just reduce the size of this window a little bit, and let's take a look at some images and some scan modes, and to help us discuss scan modes, I am going to bring up Channels. I am also going to introduce another tool we are going to be using throughout the scanned process and this is called the Info panel. We are just going to get started with these and that will help us transition into working with and controlling our scanner.
These are four kind of basic images that we will work with and we capture images with the scanner. The first image we see here is a line art image and we are going to zoom in this line art image, and we are going to see, this is one of the very basic kinds of images we'll capture with the scanner. Some images that you capture will just have black and white pixels that we have here, and notice that there is only one channel in this image. When we are capturing black and white, are sometimes called line art scan mode, this is what we end up with. One other thing to introduce at this point is the actual values assigned to those pixels.
I am going to zoom way in here, and I am going to go to my Info tool, and I am going to look at the value of the black pixel and the value of the white pixel, and notice down here in my Info tool, I have K value which stands for black and notice it's 100% on the black pixel and 0% gray on the white pixel. That's one way to look at the grayscale value of this image. There are only two shades of gray here, black and white. There are two ways to measure grayscale value, and this is another way over here on the right side of the panel, the RGB value.
I am going to go back to that black pixel and notice the RGB value is set at 0 and the K value is set at 100. So when I move over to the white pixel, notice how the RGB goes to 255. Notice those two scales are inverted, this is not my fault. It's kind of just the way it is. But you want to get used to and that's why we are starting now talking about RGB values and they are really grayscale values on the scale of 0 to 255. So if you are just working with straight black and white images, it's okay to think in terms of K value, but we are going to be working in the RGB world, so it's good to start thinking about it now.
So remember a black pixel is 0 and a white pixel is 255. So that's the simplest image. Let's move over to our Moose image. I am just going to move zip over here, I am going to move the Moose back in here, and let's zoom in on our moose image, all the way in, and notice that unlike the simple black-and-white image that we have here, this is a multi-tonal grayscale image. And notice we have pixels with grayscale values. But first before we talk about the detail of the grayscale values, let's look back down here at Channels just like he black-and-white image, where we just have two shades of gray, black-and-white with one channel, we still have one channel.
But on this channel, we can capture more than one shade of gray. Let's go back down to our Info panel here and notice that the white pixels, look at the K value close to 1%, the dark ones are getting up towards 100. But when we are dealing with multiple shades of gray, again, we need to start thinking of it in terms of RGB values. So let's look at the RGB values. We are looking right here on our RGB value close to 255, whereas the darker ones are down close to 0. So these two basic images we can tell our scanner to capture in straight black-and-white mode, in which we get one channel of pixels that are either black or white or we can ask our scanner to capture in grayscale mode, sometimes called a grayscale photo or black-and-white photo.
Different scanners and different software use different terminologies, but the results are the same. One channel with multiple shades of gray in our pixels On an image like we have with Zip here, and let's enlarge Zip a little bit and zoom in, here we go. And we see that this image when we zoom way in is still again pixels, and once again we have multiple shades of gray. A lot more density of grayscale value, but notice that the lighter pixels have higher values to them, and the darker pixels have lower values to them. And then the other and final kind of image that we can capture with a scanner is an RGB color image.
And boy, this has got a lot of color in it, lots of brilliant yellows and reds and some blues, but notice the big change here. Instead of just having one channel, we have got three, but here is the important point about understanding how fundamentally a scanner and output devices work with your scanner. When we look at these three channels, the red, the green, and the blue, notice that your scanner can only capture grayscale. I know what you are thinking, hey, that's color there, but that color is not actually captured by your scanner. And here is one of the fundamental truths of working in the digital world.
all colors are created by output devices. When you capture an image with a scanner or digital camera, what you are actually capturing is 3 grayscale channels, to which we assign various shades of red, green, or blue, and then our output devices take those shades of red, green, or blue in the case of a RGB monitor, paints them with red, green, and blue. One a printing device you may print them with Cyan, Magenta, Yellow and Black. So on a scanner, depending upon which mode we select, we get various number of channels, shades of gray, and then in some cases multiple shades of gray.
So in black and white modes we get one channel, which is black-and-white pixels. When we work in grayscale mode, we get one channel, but we get multiple shades of gray assigned to those pixels on a scale of 0 to 255. When we scan in RGB color mode, what we end up with actually is 3 grayscale channels to which we then assign color and output. And if you're thinking about this, this isn't the first time you've kind of realized that what we actually capture is grayscale, which by the way is why they are called digital scanners or digital cameras, they only capture 0s and 1s, black-and-white, or shades of gray.
You may be thinking, then how do we actually control the color? We control the color by controlling the shades of gray in our image. To remember the fundamental truth, all color is created by output devices and when you truly understand this, then the desktop publishers lament, make sense, oh, what I see on my monitor doesn't match what I have on my printer. What I saw came off my digital camera doesn't match what I get on my printer. I have two different printers or two different monitors and the color looks different. Well, it kind of makes sense now, doesn't it? We have the same shades of gray, but they are all being interpreted a little bit different, because all color is created by output devices.
One final point to make here is that one of the things we can decide to do is convert these pixels into vectors, which are the other basic building blocks that we have with digital images. More on that later.
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