DPS 3-10: Photoshop LAB Color Review, D200, new chargers

In this issue we've got a complete review if the exciting new color correction book from Dan Margulis, , as well as info on some great new products that have been introduced just in time for Christmas. In particular, check out for the Nikon D200 specs. We've also still got a couple slots for our second Grizzly Bear & Puffin week in July 2006, so .

The Photoshop LAB Book: The Canyon Conundrum

Could you fix the image on the left of Delicate Arch?

Can you turn 
this image

this image?

If you are experienced Photoshop user, I'm sure your answer is "yeah, probably, but it might take some work." The first time I worked on those images it took me a long time also. Then I read Dan Margulis' book and discovered how useful the LAB color space was for color correction. Sure, I'd always known that it could be used as a clever way to do Luminance sharpening and some tone correction, but never thought much about using it for color correction. Now it is one of the first tools I consider when I have an image that requires some color heavy lifting.

After reading the book (or more honestly flipping through for the tidbits I could quickly understand) I was able to re-process this image and the others shown below in only a couple of minutes each and produce results that were superior to what I'd accomplished previously with oodles of layers, masks and fiddling. What fun! A more thorough reading revealed a whole new world of color correction opportunities using the very powerful LAB colorspace.

The Magic of LAB

As someone fascinated by the way human vision works, I've always been interested in the LAB colorspace. For those not familiar with LAB, it is a representation of color that separates the luminance (overall brightness or "lightness") or "L" channel from the color channels--"A" and "B". While we most often think of the human visual system as being RGB, it also relies heavily on the contrast between Red and Green and Blue and Yellow. Not by coincidence, those are the A and B channels in LAB. The result is a very powerful colorspace that can cause dramatic changes in our perception of an image by creating and destroying contrast easily and quickly. And by having the L channel separate from colors it is possible to do operations including sharpening without accidentally adding color casts.