How to use the curves tool in photoshop
Votes: 325If you're like most people who work with Adobe Photoshop you use the "curves tool" as a magical tool that does magical things, and are not quite sure why.
Here we have a 45 degree black to white gradient, showing every shade of gray, a perfect example to show what curves actually do.
Now here is the curves profile of this image
As you can see the image is not so much black, and not so much white, as it shades of gray, profound I know. I'll get the heart of the matter very quickly,Curves allows you to re-assign light and dark values to color. Example: what is the difference between a deep blood red, and a light, almost pink red? Light or dark values.
Ok now why is this better than, say Levels or "brightness and contrast" (never use those tools EVER!). With curves we can "nudge" some darker values lighter, while still maintaining the lighter colors, by not blowing them out to complete white like a contrast and brightness might.
This is a typical curve you might use to light a photo, but to really grasp it, lets look at the gradient image again.
So, all we have done is remapped the curve to give the once darker pixels more "lightness" to them, but yet not burned out to complete white, although hard to see, it's in there.
The real world
Here is a photo of my son, looks like dad goofed and let that shutter speed a little to quick (yes I like to shoot manual). Now if I used a straight brightness or even levels, I would loose my highlights in the glass and other "white-ish" objects, why loose color when we can keep it. Here is the curve I ran on it.
And the corrected photo .
Ahh, much nicer, with no color loss. Now the JPG format will clip out the light colors and the dark colors.
Final thoughts
Experiment, this was meant to just you a basic understanding of what curves can do, experiment with a curve that is no curve at all, but a flat line, or the popular "S" curve. Also remember not to let the curve go flat at the top or bottom (within reason), also experiment with using mutiple points.
This is not an exhaustive list of what the curves tool can do, again play with it. Learn even more here.
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Posts: 1
Reply #1 on : Wed May 02, 2007, 13:43:50