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In the previous movie, we saw what making a Levels adjustment does to the colors in your image, in this movie we are going to see what using these Auto options, Auto Tone, Auto Contrast and Auto Color, how they will affect the colors in your image. So I am going to start out by taking my Histogram panel, tearing that off and putting that somewhere where it's covering as little of the image as possible. I'm a bit limited here with my screen space, hopefully, you have a bigger monitor or a finer resolution than I have at the moment, but mine is set to a low resolution for the screen capture software, so that we can see this on the video.
And then I am going to click on my Info panel, we need to see that as well, and I might just tear that off and put that up at the top, and then we'll close the Navigator, since we don't need that. And the other thing that I need is a Levels adjustment. Now I am going to add the Levels, not as static adjustment from here, but as an adjustment layer from down here, because it's always better to work with adjustment layers, since they are nondestructive.
And before I affect any change, I'm going to use my Color Sampler tool and lay down some samples. We'll have one in the sky. There is very little highlight information or virtually no highlight information in this image, but I am going to choose what are currently the brightest values as best I can gauge them, some are out there, and we'll also do one in the shadow area. So we have three sample points and we are going to see how these numbers will shift, so I think I'll move this over here. So we can clearly see the three sample points, and we can see our histogram and we can see our Info panel.
Now, if I click on Auto, what actually happens when I click on Auto? Well, we get the last Auto adjustment that was used which may or may not be what we want to use here, but we want a bit more control, so I am going to undo that by pressing Command+Z or Ctrl+Z, and I am going to hold down my Option or Alt key and click on the Auto button, where we have the chance of choosing exactly what happens. Again, I am running out of room here, but I am going to put that about there. So we have three different algorithms to work with.
Enhance Monochromatic Contrast; this is essentially what I did in the previous image. I was working on the RGB channel and I got the white point and the black point sliders and I moved them towards the center, and when we Enhance the Monochromatic Contrast, if I now change the color readout on my sample points to HSB, we can see that there is very little, only one slight change in the Hue of the three sample points when we use this option.
However, where I have to choose Enhance Per Channel Contrast, then the Hues shift quite dramatically. Now I am not saying that that's necessarily a bad thing. If the image looks better, then the image looks better, but I am just pointing out that when we use this option, the colors are going to shift. Now this is equivalent to choosing the channels one-by-one, which I can't actually do while I am in here, but it would be choosing the individual channels, the red, the green and the blue, and then moving that individual white points closer towards the center, and then we have our third option, Find Dark & Light Colors and this will find currently the darkest pixel in the image and map that to my Shadow target, which is this right here and finds currently the brightest pixel and map that to my Highlight target.
So that brings up a whole can of worms right that, what are my Shadow and Highlight targets? Well, we can go and take a look at what they are by clicking on them and currently we see that the shadow clipping is 0, 0, 0 in RGB terms, i.e. it's pure black and it's as black as it gets. Now this is fine if you are creating an image destined for screen, no reason to change it. If you are sending your image to be printed on offset printing press, you might want to consult your printer as to what the best shadow target values are.
I am going to give you some target numbers that will work with an average key image, by which I mean an image where most of the information is clumped within the Midtone regions, which is essentially what this image is. These numbers are 65 for the Black, 53 for the Magenta, 51 for the Yellow and 95 for the Black. That's going to affect the change that is indiscernible on our screens, but it's going to mean that the Black is slightly less solid than the original target point.
So now I am going to do the Highlight values and we see the current Highlight value is 255, 255, 255 i.e. that means no information or no ink at the brightest point of your image, and that's fine if you want completely bright whites in certain areas of your image, totally fine for screen. For print, we might want to make it a very light gray, so that there is a very small dot of ink at the brightest points in that image and I am going to make the value 3, 2, 2 and 0, for the Cyan, Magenta, Yellow and Black respectively.
So now when I find the darkest and lightest colors, specifically, it's mapping the darkest and lightest colors to those Shadow and Highlight values that I just put in there, I can opt to save those as my defaults, should I choose to. We have a Clip of 0.1% which means that the black and white points are going to go slightly be on the ends. So in this case, with the clipping as it is, Photoshop is second-guessing us in a way and it's interpreting the very ends of the histogram as being irrelevant information, which it may or may not be.
So you might want to set the Clip to 0 or we might just want to leave it as it is, I am going to leave it as it is. We also have another option that's going to affect the color and this is the Snap Neutral Midtones and we can apply that on any of these three algorithms. Now I am going to go for the Enhance Per Channel Contrast and when I snap my Neutral Midtones, take a look at how this affects the color in the image, I'll do that once again, I'll turn it off and then turn it on again. So what's happening here is it's finding the current median brightness value and remapping those to the target Midtones.
Let's go and take a look at what the target midtones are. The target midtones are completely neutral gray, and there's no reason to change these. I am going to leave those as they are. But this can be especially useful if you have an image with a colorcast, and we'll see how when we look at Color Correction, correcting colorcasts, how snapping our Neutral Midtones to our target midtone value will fix all sorts of problems within our image. Now whether or not it's a desirable change here, I'm not entirely convinced.
Yeah, in fact I think it is. The image gets slightly warmer when we snap the Neutral Midtones, so I am going to go with that. But the important thing is here that the Enhance Monochromatic Contrast will not affect a change in the Hues, whereas the Enhance Per Channel Contrast and the Find Dark & Light Colors; both will. Whether that's a good thing or a bad thing is your subjective decision, based upon how it affects your image.
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