Class Introduction: Remove Moire Patterns
In this session, we're going to cover Advanced Retouching. In a previous lesson, that's part of the complete guide, we covered retouching essentials. And that's not always going to address everything you gotta do. So in this session, we're going to get much more deep into retouching. And let's dive right in. The first thing I'm going to do is show you how to get rid of moire patterns. Moire patterns happen when you photograph something that has a regular pattern to it like the weave of fabric. And you're photographing that with a camera that's using a grid of pixels. And it's kind of like having two grids that don't perfectly align. I don't know if you've ever seen it before, but if you take the screen that you might find in a screen door, and take two pieces of it. Put it one right on top of the other, then rotate them slightly. A lot of people have seen that effect. But if you do see it, you get a weird interference patterns between the two screens. Well, the same thing happens when ...
you take a camera that's capturing a grid of pixels, and you point it at a grid of fabric or something. You can get a pattern. Let me show you what one looks like. If you look closely at this, you see these odd colors that are in here in this pattern. Well, to avoid that, camera manufacturers put a filter in front of the camera sensor that actually softens the image slightly. And that prevents this from happening. But because it softens the image, often times manufacturers will create two versions of a camera. One that has that filter in front of the sensor and one that does not. So those people that shoot things like landscapes, which you don't find regular patterns in nature, they could use the version without the filter. They'll get a sharper picture. But then, those people that do shoot manmade objects, especially fabrics, would get the version of the camera with the filter. Sometimes it's called an anti-aliasing filter, but there are other names for it. And so this is what it would look like if you might choose one of those cameras without the filter in front of it and use it on fabric. So, let's figure out how to fix that. I'm going to fix it using Adobe Camera Raw. Now, this is a jpeg file. So, if I were just to double click on it, it would open it all the way into Photoshop. And we can access Camera Raw from the filter menu in Photoshop. But I'm going to go up here to the "File" menu and choose "Open in Camera Raw." Now in Camera Raw, we're not going to be able to fix this with the normal adjustment sliders that are found on the right side of my screen. Instead, I'll have to go to the top of my screen where I find a bunch of tools. And up there, you're going to find two different paintbrush tools. We want the one that doesn't have the dots around it. That's the spot removal tool. We want this one. It's called the adjustment brush. When you choose the adjustment brush, on the right side of your screen, you're going to get sliders that look a lot like the normal ones you have there when you're just adjusting a picture. But, in this case, we're going to brush these changes into the image. So, if I move one of these sliders right now, I'm not going to see any change in the image at all because I need to first paint within the image. So, what I'm going to do here is, there's a slider called "Moire Reduction," and that slider is not found in any other areas of Camera Raw or in Photoshop. So, it's unique to this tool. I'm going to crank it up as high as it goes just so I can see something when I'm painting on my picture. Then after I'm done painting, we can adjust the amount to make sure it's the lowest amount that really tackles the job. So, I'll zoom up here so that you can more better see this. And I'm just going to start painting. Now, when I do this, I want to make sure that I'm down here near the bottom, the choice called "Auto Mask" is turned off because Auto Mask tries to limit where I can paint. And sometimes it might limit me to only painting on these areas that are colorful, and we need it to paint across the whole area. But the thing you want to be careful of is when you are painting here to correct for this moire pattern is that if the object that has the moire pattern in it touches another object that is dramatically different in color that's where you want to paint a minimal amount because this is blurring the color transitions in a picture. So, if I get up here, and at the top and I see where this outfit stops and the red chair he's sitting in begins. Can you see how the color of the red chair has transferred over to his outfit? And that's because of this choice called "Defringe." Before I fix that, I'm going to look down here at the main portion of the fabric, and I'm going to adjust the amount setting for moire reduction. I'm going to bring it all the way down to zero. And then I'll slowly bring it up, and try to find the lowest setting that really tackles the job. And I think somewhere right around there is fine. Because now I have a more accurate idea of how big of a problem I have up here where those colors are blending together. If you watch that, I ended up with a setting of-- I can't even read that-- it's either 56 or 66, but if I continue bringing it higher, you'd see that that color blends even more. Choose "Undo" to get back down. Well, up here at the top, above the sliders, is a choice called, "Erase." And if I have that set to erase, I probably want to feathering turned up a bit so that I get a soft-edged brush. And I'm just going to try to get it off of the edge of the fabric. So I don't get the color from the chair blending in. Now, it might see some of the moire pattern appear in that area, and if I do, I just got to choose a smaller brush and maybe lower the slider a bit when I paint it in. But most the time you can remove it from areas where there's a transition between two distinctly different colors because this moire reduction is going to blend colors together and that's how it attempts to get rid of the moire. Now, to show you before and after, all I'm going to do is hit the delete key. The delete key is going to remove this little adjustment pen that's here. And then I'll type "Command Z" to undo it. That's "Control Z" in Windows. So you can see before and after. I'm going to click "Done" there.