Knowing Your Limits: Histograms in ACR
This session is about knowing your limits, which means are there's some things we can think about when we're adjusting and working with our images to try to avoid running into problems and so a bunch of stuff to talk about so let's take a look first off, we're starting camera because that's, where I often start in general with my images and then we'll work our way into other kinds of adjustments, so I'm just gonna open any old image here in came a raw and one of the things that I pay attention to, at least when I'm done adjusting and image just to see are there any problems that were introduced buy me performing an adjustment would be toe look in a few areas one is the history ram up in the upper right of my screen, you're going to find the history graham it's just a bar chart that tells you the brightness values that are in your image and I really wish adobe would put a grady in't underneath it that would show black on the left and white on the right in all the shades of grey in betwe...
en in between, because if so, then all this bar chart would do is tell you if the shades found within that grady in't were present in your image or not, but unfortunately they don't put it in there, so you have to just visualize it if you want to see what I'm talking about if I just make an image and photo shop and I go teo levels right here. Do you see this bar with black on the left? White on the right? Just imagine you took that. You copied it and you transplanted it into curves so that that same bar that has black on the left and white on the right would appear instead just below this sister graham I beg adobe one day at it uh, down here because if it was, there would be dramatically so you understand what's going on with the history ram. Otherwise, you have to be a seasoned user toe to know what that this is. So anyway, if you have a gap on the right side of your history ram it means you have no whites in your picture. That means there's usually not necessarily an issue with your image, but it just means there's nothing. You have to be overly concerned within the highlights your picture you haven't lost any detail. If there's a gap of the left side, it means you have no black and your picture on dh that could be fined as well. Gaps are not harmful things, but spikes can be a spike on the left side indicates you have an area of black in your picture and as long as that's a really small area that's, fine, but if it's a large area, it might be something where if you were to back off on some of the sliders that you've applied, you might feel to regain some shattered detail. If you similarly had a spike on the far right of your image, that would indicate you have white in your picture, the taller despite the larger the area of white. In the meantime, I allow it to have a tall spike on the right is if I have the noonday sun in my photo, because I don't expect the son to have any detail unless it's at sunrise or sunset so I would expect a big spike. But if the noonday sun is not in my picture than I would not usually expect to really tell spike so that's one thing I look at is the ends of the history ram and in this particular case on the left side, I do see a spike indicating we might be able to get further shattered detail if we were to somehow eliminate that know what I'm talking about. Those spikes there's actually two ways of thinking about it one is, you will occasionally find the spike on the end to be in color, and then other times you'll find that it turns white. And so I want to show you the difference between those and see if I can cause it to happen on both sides and really how we convince allies it because it's an indication that we're starting to lose detail in the highlights of the shadows. So what I'm gonna do in this case is I'm going to pump up how colorful this images we're bringing up saturation, and I'm going to just do something to see if I could get some of my, uh, shattered detail so that all I have is a colored spike just try to do something where I just had a colored spike so a colored spike what that means is behind the scenes your image is made of three colors, those colors are red, green and blue, and a spike on the end that is in color means you're losing detail in one arm or of those three colors that make up your picture. And what happens is if the color of the spike is sai in magenta yellow, you're losing detail in just one of those pieces. If it ends up turning red, green or blue, you're losing detail in too out of those three pieces, and when it turns white, it means you're losing detail in all three and there is absolutely no detail in some little area of your picture. So if you want to see where it's happening and see how it might affect your image here's what we can do is if the spike is on the left side of the history ram then that means it's thinking about the darker portions of those channels and so you go to a slaughter called blacks because that thinks about the darkest part your image you hold on the option key alton windows and click on that slider and it'll usually show you the areas that is thinking about right now they're really hard to see because they're yellow but they're in there if I bring up the saturation even higher I can get them to be larger that uh and so those are the areas we're starting to lose detail now it doesn't mean that that's completely an issue that I'm gonna have to deal with it and make it so we don't lose detail in those areas, but what it does mean is I should inspect those areas to see if they contain any important detail that I might be losing so I'll just kind of stare at that area I'll let go of this slider and try to determine where it is in my picture okay? It looks to me like it's in the brightest, most colorful areas of the trees the green area of the trees and so that means I might want to take a close look at those areas to see if I can notice that it's losing detail what it means that if I were to do something to avoid that spike, I would be able to see a little bit of extra detail in those trees if the spike is in color than usually. The thing that's going to allow you to regain the detail is to lower the saturation of your image, and you can either lower the saturation as a whole by bringing down the saturation slider. I'm just going to bring it down. Well, I stare at the history, graham, I'm going to see that big spike on the left, I'll bring it down until the spike goes away like that. Now it would have the full detail in those trees, but in the trees themselves, I think it's hard to tell if I'm losing the detail or not, because there's just a lot of really tiny detail it's not like it's, a very smooth transition where it would be overly easy to see a slight amount of detail off. The other thing I can do is if I find the rest of the image benefits from having the saturation turned up, then if I ended up coming in and and previewing it by holding down the option key and clicking on the black slider. I'd look at it look at what part of my image that's on top of I've noticed it's the yellowish areas or greenish areas in the picture and instead of bringing down the saturation on the entire picture, I could instead come over here in these little tabs in one of the tabs is the hs l tab in there I could just tone down the saturation on just the yellows in just the greens in that way I could retain the saturation I have in the sky in possibly other areas, so trees air usually actually a little more yellow than the r green, so I'm going for the yellow slider and if I bring that down you see in the history graham that spike start to get shorter and shorter and I could bring in town until it goes away if it was more important, have detail in the trees than it was to have them colorful it's all what's most important, if the color was more important than I'd say, fine that's more important in the detail so that's one thing to look for which he is what's known is clipping and when it's a color spike on the end it's called saturation clipping it usually means something is so saturated that is starting to lose detail in one or more of the channels then the other thing you could do is have clipping in where your highlights or shadows becomes solid black or solid white, and that happens when the spikes on the end of the history graham instead of being in color, they turn white. So if I were to bring in one of these sliders that would darken the dark part of the image enough, I might be able to get a big spike on the left side of the history. Graham so if I zoom up to it, do you see the big spike that indicates there's a a large area of solid black taller? The spike is the larger the area is, and if I want to visualize it seat on my image to see where this in case it's not important, I go to the black slider again any time the problem is on the far left of the history and it's always the black slaughter I go to, I hold on the option key again and I click and now I'm going to see where exactly that details being lost. I ignore the areas that are in color because that's what we're thinking about saturation clipping, we've already talked about that and instead I'm looking at the areas that are hitting solid black and I'm trying to side are those areas important to have detail in? And if so, it's the black slider, I might adjust teo, get that detail back if I move the black slaughter towards the right, I'll brighten up the blacks, and what I usually want is I do want a tiny spike on the left side of the history, graham, because I find almost every image looks better if it has a very small area of black, I just don't usually want a huge area to black unless it's something, we're really trying to make something look silhouetted with absolutely no detail. So for me, having this amount of black right here is fine, uh, that's going to give my image a nice, deep bass in the dark part? If I don't have black in my photograph, then the image can often look kinda hazy. It just won't have the depth that other photos have. If the spike that you notice in your history, graham is instead on the right side, either a colored one or a white one. In order to see where it is in your picture, you're going to go to the whites slider, I'll turn up the white slider to see if I can get a spike to appear there just we have something to look at and then hold on option ultima windows and click on that slider, and I can see where it is if it's an aryan color, that saturation clipping many word have partial detail in that area, but we could have maur if we were to turn down the saturation on whatever that area is. So if I stare at the area that has that big blue blob on the right and then let go, it looks like blue sky so I could lower the saturation on the blue sky. And if I did that part right there might eventually go away. So I came over here to the hs cell sliders, goto blues or it might be awkward, but blues bring it down, and if you look at the hissed a gram on the right, do you see it starting to lose that? But the sky, unless I can start seeing poster ization where I can see like stair stepping across this guy, this guy doesn't really contain important detail it's not like it's got texture like the way we've a fabric or or something in it so it's up to me what's more important, the saturation that I'm achieving or detail uh, and if the spike turns white, then when you go to the white slider and you option, click on it, you'd start seeing white areas, and I could see a very small amount of white in there, I think it's white, yeah. So that's, one thing that I end up looking at now, there are other ways of finding out if that's happening let's, take a look at those I'm going to do something where we don't have any of that clipping just by moving some of these sliders around and be lowering my saturation a bit as well. Okay, another way to tell if this is happening is instead of looking too closely at the history. Graham, just look at the triangles that appear in the upper right in upper left of the piste a gram, so keep your eye on those I'm going to bring up the saturation and let's see if those changed from black to something else. When eventually I get a spike in the left side, you notice that the triangle changed the same color as the spike that's there. So if the triangle changes to a color, it means we have saturation clipping and it's in the dark portion of the image because the one on the left is for the dark areas, and then if I'm able to get it to happen on the right side, I don't know if I can get it far enough with saturation to get it to happen, they could have to brighten up my highlights now let me see if I can. Okay, do you see it starting to happen on the right side? The little triangle changed color that means I'm starting to get some saturation clipping in the highlights and so I might want inspect those areas and if those triangles change from color instead washington right still color changes toe white or watch the one on the left it changes toe white, then that means that I have solid black or solid white in that picture and so it's just kind of indicator if I've gotten that or not now with this image, I wasn't looking at the picture to see if it looked good when I was moving those I was just trying to get things that happen in the history graham other things you can do is with those little triangles you can actually click on the triangle if you click on the triangle it's goingto enable a a warning that will actually go and show on top of your picture, I'll click on both of them. I'll click on the one on the left and when I do I do if you can't see it or not but there are some small areas within my picture they have a blue overlay on them if I move the black slider to darken the blacks even further you see the blue on the image what that showing me is the portion of my picture that's losing detail then I'm gonna click on the triangle on the right side and see if I can get areas in the highlights to start losing detail, and maybe I bring this up a bit. He see a very smaller of red eyed over in here, and I'll bring up the saturation. Stephen, get further with that. So what happens is blue is indicating the lost detail in the shadows. Red is indicating lost detail in the highlights. The only thing you have to be careful with there is that the, uh, let's see here it thinks a little bit differently between those two. So what I would say is this in the shadows, the blue overlay, if I remember correctly, will on ly show up where it's truly black, it won't show up where we getting saturation clipping, so if I go on option, click on the black slaughter, you'll see a much larger area showing up there with the warnings on it. It's on ly the areas that are solid black, that air getting the overlay in the highlights, it's usually in your blue skies and things where you start having that happen first, and it usually makes it so it has a little bit of poster ization where doesn't look smooth, and so it ends up showing you not just where it's solid white, but I believe it also shows where you have saturation clipping, so if I go in here, do you see those little blue areas in this view? They should have some of them showing up here, but it's just slightly is thinking slightly differently when it's doing that so that's, how you can think about this for me personally, I don't like seeing the red and blue on top of my picture because they don't print out and I find it to be distracting, and so I personally have those little triangle things turned off instead, what I do is I adjust my image and optimize it until I simply like the look of the picture, which maybe I'll do here bring up my exposure little bring down my highlights because they're a little on the bright side, maybe add a little bit of contrast, make it pop a little and what'll happen is once I'm done optimizing this image only when I think I'm getting pretty good with the look of the picture, am I just going to start glancing at the history ram to see if there's any indication there might have a problem? So what I'm done optimizing right now, I noticed spikes on both ends on the right side is really tall. Colorful spike so I go to the white slider and I say, well, where is that ok sky's losing some detail and if I want to get that detail that I'm either going to bring down the saturation as a whole, see if it goes away, I'll bring it down however far I think is appropriate for that image if I still have it and I think I need that additional detail I'll goto h s l and then I'll target just the color where it was happening and then I look at the dark area of the picture and I'll say, hey there's a white spike there that means I have no detail the shadows option click on my black slider make sure have a small area of solid black and if I don't have enough, I'll adjust the blacks until I do if it's too big of an area I would have brought up the blacks teo prevent that from happening but in the end nobody else is going to see your history ram when you print your image or shows up in a magazine, it doesn't show the history and next to it so it's just like your speedometer in your car it doesn't mean that you should be staring at that state of the road you want to just glance at it to see is there something that you might want to be concerned with but if having something be more saturated is more important than detail, then it might be fine. Teo have saturation clipping that kind of stuff.