Learn how to adjust exposure and shadow levels in this Adobe Photoshop CS2 Advanced training video.
Tags:adobe,adobe photoshop,adobe photoshop cs2,exposure,levels,macromedia,shadow,shadow levels,total training
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Now I am going to move this preview down a little bit here so that we take in more of the sky and I need to figure out which portions of this image are blown. In other words, what highlights I am loosing inside this image because it is a very bright sunny day, I am shooting out the window, I am relying on Automatic Shutter, Automatic Aperture and so on for my camera. So there is bound to be some blown highlights inside this image. And you can adjust for the highlights inside the image using the Exposure option, so Exposure is analogous to the White slider inside the Levels Dialog Box, Channels is analogous to the Black slider and Brightness is more or less the same, it's very similar, put it that way to the Gamma Control. It is measured differently however.
If I want to bring back some highlights, I would lower the Exposure value, if I want to make the highlights brighter, I would raise the Exposure value, so very easy stuff here and you can track your changes not only by looking at the preview, the image preview, but also by looking at the Histogram at the top of the screen. You also have that option of Alt+dragging. Notice that if I Alt+drag the Exposure Control or Option+drag the exposure control there on the Mac, any place inside the image preview that's not black is getting blown in one channel or other, so it's turning white in one of the three color channels.
Now I am going to move here just a little bit inside the image so that we can see, notice this how a big portion of the image actually starting to blow right at this level, when I go to about 0.6. Here let me zoom out some more so we can take in more of the image at a time, and I will run that again, right. So anywhere where the image is turning white means that we're blowing in all three channels, so that's bad. We don't want to see that happen, or by the way, you can keep track of these changes on the fly by just turning on the Highlight check box right here, and if you do that, if you turn on the Highlight check box, you don't have to do that little sort of Alt+Drag thing, the Camera Raw dialog box will just show you pixels that are blown in all of the Channels. So it's showing you things that are completely going way too white, which are really the portions of the image that you're most concerned about. So I would suggest you, keep Highlights turned on, especially if you have an overly bright image like this one.
Now, one of the miracles of Camera Raw is that you can bring the colors back that would normally be completely lost to you, if you would shot to JPEG so when you shoot an image from a digital camera to JPEG, if you've got blown highlights inside that image, then those highlights are blown, whether you like it or not. There's nothing you can do to bring those blown highlights back, if they are truly gone completely to white.
However when you're working with a Camera Raw image, you stand more of a chance, not a definite chance but more of a chance of bringing those highlights back. So when you first enter the dialog box, Auto is turned On, which means Camera Raw has decided an automatic setting for the Exposure, and we have blown highlights at this setting and this would be pretty much the same thing that camera would do, if it was converting it to JPEG. It would leave these highlights blown, but inside Camera Raw, you stand a chance of reducing that Exposure value and getting those highlights back or not. So, you may get your highlights back in some cases, you may not get your highlights back in other cases.
Notice if we take the Exposure all the way down to nothing here, this is the as low as we can go, it's the -4.0 by the way, and this is measured in F-stops, just for those of you who are digital photographers who are familiar with working F-stops in the past, in the good old days and traditional film days. And that is the lowest setting and we can see here that we still have a few blown highlights, not that many but the image is also way too dark, we are not going to get those blown highlights back so we might as well choose a better exposure value. But it is worth noting that you can recover many of the blown highlights inside of an image using this control.
We also have the same control with Shadows but we're trying to recover flat shadows, we're trying to make sure that our shadows don't flatten out in other words. Now this is a pretty high Shadow setting, so this is taking most of the dark grays inside the image and sending them to black. If we want to see exactly which pixels is going solid black on us, we can Alt+Drag this control or Option+Drag the control on the Mac and any pixels that are not white are going solid black in one channel or other inside the image or you can also turn on the Shadows check box. Now I don't use the Shadows check box nearly as much, because I rely so much on Automatic metering, you may find this helpful if you find that your shadows are going too black on you.