Auto Levels vs. User-set Levels
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#1. "RE: Auto Levels vs. User-set Levels" | In response to Reply # 0
jnscbl Basic MemberMon 04-Aug-03 10:08 AMFirst, there is a difference between autocontrast and autolevels. I'll let someone else explain. Once you know what they do, you can duplicate them manually very easily. Second, using either is sneered upon as a beginner's shortcut (like using Program mode). So don't expect to win any converts. Third, it actually is destructive to a low contrast image. But then, not everyone likes low contrast images. Fourth, it also depends on your printer. I always avoid pure black on my printer, as it looks terrible. I find autocontrast a quick diagnostic tool to locate trouble spots, both black and white. But then I undo it. I don't expect to win any converts either; I do things visually, rather than graphically, at least in visual arts. Maybe someone can touch on the superiority of the histogram at this point. Fifth, expect a lecture on the superiority of Curves. Sixth, it's never too late to learn a better way. At the same time, your earlier efforts are probably still plenty good enough. Don't sweat it. Last, what do I use? To fine tune, I usually use brightness/contrast. To maintain continuity among a series of related images, I use Levels. Either way, boosting contrast does increase color saturation to some degree.
--scott
"Less is not more. Enough is enough. Less is less."
David Vestal
--scott
"I am always doing that which I cannot do, in order that I may learn how to do it."
Pablo Picasso
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#2. "RE: Auto Levels vs. User-set Levels" | In response to Reply # 0
jrp Charter MemberMon 04-Aug-03 10:14 AM
Exactly right, in my case. If unhappy then I go to the quick white point/black point adjustment routine and keep on fine-adjusting if not satisfied, which seems to be more mood-dependant than image-dependant. I don't shy away from pitch black -probably a mistake, now that I see Scott remarks- and fully agree with the rest of his comments.
Have a great time! 😉
JRP
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#3. "RE: Auto Levels vs. User-set Levels" | In response to Reply # 0
Try autolevels on a sunset or a mostly monochromatic image and you'll see just how destructive it can be. Throw auto at a low contrast foggy seascape scene and you'll see that you need to understand when you shouldn't use a particular tool.
The auto controls can be quite convenient, but if you use them at least follow Bruce Fraser's advice and learn to use a better (than the default) algorithm for the levels calculation as described in his article at CreativePro:
http://www.creativepro.com/story/feature/17164.html?cprose=3-30
I'll sometimes use auto controls as quick and dirty tweaks to images I don't have the time or interest to do right. But working as you are with your best shots, I'd never hand over the controls exclusively to the computer. Levels is just one of the tools I use, more often I use curves since this tool allows a much wider range of adjustments.
I would suggest that however you work, you use an adjustment layer rather than adjust the image directly. If you want to use autolevels as a starting point that you will fine tune, go ahead and create an autolevels layer using Bruce's "Find Dark and Light Colors" and "Snap to Neutral Midtones" example. I set zero clipping for highlights and shadows since clipping loses detail. Then you can manually tweak the automatically generated levels to optimize the results.
Why go through the hassle of an adjustment layer? Because you can change your mind at any time, not just during a particular edit session. I too use the visual approach to image editing and I find that as I learn more and better approaches to image editing it's great to have an unadulterated base image to go back to.
If you don't have a calibrated workflow, any fine tuning will be misguided since what you see isn't what you're going to get. Your scanning workflow is also important. You just made a discovery that is leading you to look at the potential of your images - keep that process of discovery going. For example, if you want more contrast and saturation on an image, try using s-curves:
http://www.outbackphoto.com/workshop/photoshop_corner/essay_17/essay.html
While I don't think you should pull your hair out doing something that should be creatively satisfying, I think "don't sweat it" can be a formula for mediocrity. Why not push harder to really make your best shots better?
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#4. "RE: Auto Levels vs. User-set Levels" | In response to Reply # 3
pretzelboy Basic MemberWed 06-Aug-03 11:25 AMI love checking out everyone's process, especially when discussing PhotoShop. There's always something to learn. I generally use the curves command. Sometimes I use auto-curves, but almost always I end up tweaking it in one or more of the channels or by changing the contrast....(when I discovered the adjustment layers gig, I just about died and went to heaven...hear hear BJ!)
But I think the bottom line is how it looks to you in your set up. If it looks good, who cares how you got there (unless of course it took you three days and a gazillion different commands....then you need a more stream lined approach...)
PB
"When in doubt, duct tape it"
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#5. "RE: Auto Levels vs. User-set Levels" | In response to Reply # 4
Absolutely, what looks good to you is the only thing that matters. Having flexible files that can be tweaked in the future has become especially important to me since stuff that looked perfect to me a while back now doesn't look quite right. It's always nice to have the "negatives" just in case you're not above second-guessing yourself .
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I remember BJ posting a note on auto levels not always giving the best possible picture, but not much other discussion of this subject. So my question is what do most people do in adjusting levels. Do you try auto-levels first and only if you are not happy go to auto-levels, or what? Your process would be appreciated.