# Understanding Histograms Part 1

Lesson 19 from: FAST CLASS: Understanding Light

Mark Wallace

# Understanding Histograms Part 1

Lesson 19 from: FAST CLASS: Understanding Light

Mark Wallace

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## Lesson Info

### 19. Understanding Histograms Part 1

Lesson Info

Understanding Histograms Part 1

what we're doing here is we want to look at this photo. This is just a very technical photo. And what we have is we have a reference card in this and this is going to show us what should be white. What should be middle gray in what should be black and how that works. And so, um, first, I haven't explained really how a hist a gram works. So I need to explain that because we're gonna be using that as our reference for all of this and the history. Ram is this guy right up here and that's in light room. You also see that on the back of your camera? Also, we're going to set their white balance really fast just by clicking on this middle gray here. So that's all set. All right, So, um ah hissed a gram works like this, I'm gonna zoom this in so you can see it, and then we'll explain what these different levels are over here on the TV. So a hist a gram. What? We're measuring our, uh, the intensity of luminosity, a different levels. So in other words, over here this represents absolute black, a...

nd this represents absolute white, and this represents Middle Gray. And we're saying, all right, pixels. So all the little dots in our camera were saying, How many of you are absolutely black? How many of those? And so we scale this. This many are absolutely black. Let me say Okay, how many of you are just one shade above absolute black and we chart that and then we keep going until we're in the middle, graze until we're in the highlights and until we're in the absolute lights and then we get a distribution of all those values. That's all the history Graham is. And so some people, I tend to think that there's a good history, Graham and a bad history. Graham, there isn't hissed. A gram is a measurement of the values in her image. Just like a thermometer measures temperature. Or, um, you know, a tape measure measures distance. It's just a measurement tool. Okay, so that's how history works. But when we have a measurement tool, we can actually measure the values in our in our scene and show those on a history. Um, so the good thing is, we do have a measurement tool. We have we happen to have this little chart right here, and I'm gonna try something really fast. We're gonna crop this so we just take this way in, huh? When I make this custom, take that way in. Take this way in that. Now, when we're only showing this check out how our history ram changed. Now we can see that we have three values that are showing up. We have what should be black. But guess what? It's not black, right? It's is It's a dark gray and what should be gray But it's not gray. It's a little bit brighter than Gray and what should be white and it's pretty bright, but it's not absolute light. And this is what happens. Um, almost always in a in fact, that not ever seen it not happen. I've never seen a DSLR camera capture absolute black, absolute white and absolutely middle gray, um, correctly, any time. Okay, So what we have to dio is we have to in postproduction remap these values according to where they should be. But watch what happens when we do that so that scientifically is pretty close to being correct. Right? But let's see what happens to our, um uh, Well, Mr Lex, we have that. So we'll go back here, we'll reset this. And what happens is she doesn't look so fantastic. I mean, the contrast is pretty amazing there, and it looks pretty good, but it looks like we need to adjust our white balance just a bit. She looks a little bit orange. Also have to see that that some of the things that we would use the color checker passport for because it has these black, metal, gray and white tones And so you can adjust the tonality of your think of it in gray scale. You can adjust that, get it correct. And then you can use some of the colors on that palette to adjust the scene in her face to make sure that her skin tones are correct and that, um, all of the color is represented accurately. That's why I love that tool. The other thing that I'm noticing here, though, is that when we look at the hair on Lex, we're seeing some areas here where there's just no detail. It's just been lost. And the reason for that is we've taken those values and made them scientific, but what we've done is we've lost him the detail in areas that we don't want to lose detail.

## Class Materials

Bonus Materials with Purchase

Understanding Light Day 1 Presentation
Understanding Light Day 2 Presentation
Understanding Light Day 3 Presentation
Gear List
Zone Lighting Basic Setup

• Beginner