Terry <terry@xxxxxxxxxxxxxxxxxxxx> writes: > And where did you learn about it? I use the eye droppers on almost > every photo I work on but aside from that it kicks my but! Trial and error, _Real World Photoshop 5_, _Professional Photoshop 5_, Oleg Volk <http://www.olegvolk.net/>, and Ctein <http://ctein.com/>. (I learned from the people directly, not from their web sites, in those last two cases.) I think maybe Ctein's book _Post Exposure_ contributed, not directly so much as by increasing my understanding of tonality in printing. I certainly don't remember which bits I learned where at this point! To me it's like histograms -- you spend a while playing (on a decently calibrated monitor) and after a while you start understanding how the histogram (or curve) relates to the tones in the photo. I haven't taught it except one-on-one, and not very often, so my explanations may not be the most effective. Here's the capsule course, made up on the spot and worth every penny you paid for it: I'm going to teach two cheap tricks, which I *think* are enough to get you started, doing good enough work that from there you can proceed to learn the rest via trial and error. These ways of approaching problems get you started on a good broad range of the issues I've faced with photos. Both of these relate to adjustments in the RGB (composite) channel; color corrections are trickier, and while they descend from many of the same concepts, the margin of this email message (and my brain at the moment) aren't big enough to contain them (mathematician joke). "Trick" one: correcting density at a point. Note that, when the curves dialog box is up, when you click on a point in an image, the spot on the current curve corresponding to the source value in the image gets a little circle around it in the curves dialog box. When you CTRL-click in the image, a filled circle adjustment point is created on the curve in the dialog box at the point corresponding to the source value. Figure out the most important density problem in your picture, and create a control point for that problem; if it's something that's too dark, then create the control point in the low range of densities of the problem area, if it's something that's too light, create the control point in the high range of densities of the problem area. Now drag that control point up or down (and sometimes left or right a *little bit*) until the thing being adjusted looks right. Now see how bad the next-worst problem is, and repeat. Anything beyond 3-point adjustments is getting hairy, probably won't work well, and may be better approached using multiple curves corrections and masking. However, for a decently-exposed original, you can generally do most of what needs doing with one or two points. The worse the original image, the more complex the adjustments needed to fix it, the more time it will take -- and it'll never be as good as if you'd gotten the exposure right in the first place. I have wasted far too much of my life in Photoshop turning bad images into mediocre images. "Trick" two: thinking about allocating density range. This one is more relevant for images needing drastic adjustments -- more for rescuing photojournalistic images than for producing fine art. The input axis of the curve represents the densities in your original. The output axis of the curve represents the densities available in your result. If you need to greatly expand part of the input density range, you need to compress other parts of the range, because the output range represents a fixed constraint; you can't have more density range than that! So you have to rob Peter to pay Paul, as the saying goes. Important areas of the input range get expanded to separate the tones enough to make them visible, and unimportant areas of the input range get compressed to make more output tones available. The curve will be steeper than the default 45-degree line in areas being expanded, flatter in areas being compressed. All of this is easiest to do with curves *adjustment layers* if you have full Photoshop (I don't believe Elements has them, though). Those let you go back and alter the curves without re-processing (and hence damaging) the image, and let you stack independent curves each with a different purpose and *still* go back and change earlier ones, and for more complex situations it's *really REALLY* useful to put a layer mask on a curves adjustment layer -- that's "dodging and burning" assumed bodily into heaven. I'd be fascinated to know if those make any sense to anybody. -- David Dyer-Bennet, <mailto:dd-b@xxxxxxxx>, <http://www.dd-b.net/dd-b/> RKBA: <http://noguns-nomoney.com/> <http://www.dd-b.net/carry/> Pics: <http://dd-b.lighthunters.net/> <http://www.dd-b.net/dd-b/SnapshotAlbum/> Dragaera/Steven Brust: <http://dragaera.info/>
