Using LAB Color

I’ve been reading Dan Margulis’s masterful Photoshop LAB Color: The Canyon Conundrum and Other Adventures in the Most Powerful Colorspace. I thought I’d give some of the techniques he explains a try, starting with this image. I’m admittedly a piker with LAB color, but after this experience I’ll be using it more, and learning more about it.

You select LAB color on the Photoshop Image>Mode menu as an alternative to RGB (for computer monitors) or CMYK (for printing). You can’t really output anything in LAB, so a final step in any workflow in which you’ve converted to LAB is likely to be a conversion back to RGB or CMYK (depending on what you plan to do with the image).

The LAB color model consists of three channels. The L channel stands for luminance. Actually, this channel controls the contrast in the image, and appears in Photoshop as black and white. There’s some additional technical complexity in the way the A and B channels work, but essentially A controls the magenta to green spectrum and B controls the yellow to blue spectrum (both channels using a mechanism called the “opponent-color scheme”).

LAB color was originally specified by a standards body, the International Commission on Illumination (CIE). As the Wikipedia puts it, the LAB color model “is the most complete color model used conventionally to describe all the colors visible to the human eye.”

With the photo above, I converted to LAB color pretty early in my workflow. I was able to use the Curves dialog in Photoshop to easily color correct both the canyon area and the sky. By way of comparison, and to show what an excellent correction this is, here’s a link to a similar image from the same set that I processed a while ago without using LAB.

This entry was posted in Landscape, Photography, Photoshop Techniques.

One Comment

  1. katiemichelle August 30, 2006 at 3:30 pm #

    I love the tones in this one. I looked at the other version (withouth LAB) and really appreciate that picture as well, but there is something “digital”, something “photograph” about it. Had I only seen the older photo, I probably wouldn’t have thought twice about it. Its a beautiful image, its got great color and it really pops out, but the comparison is really incredible. I mean, with the LAB photo I feel like I’m ACTUALLY looking at this place, rather than seeing it on a wall or in this case a photoblog. Just my opinion I guess.

    Thanks for the compare and contrast and all the extra info in there. Really beautiful shot.

16 Trackbacks

  1. […] shows. The difference between a mundane image and one that resonates is subtle. So I say, three cheers for LAB color, which I used as part of my workflow in post-processing this capture.
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    […] larger. This is a fairly straight studio shot of gladiolas in a vase. I converted it to LAB Color in Photoshop, and then inverted the Luminosity (L) channel (by making sure only the L channel […]

  3. […] photograms shows capillarity, or capillar action, in a leaf. The version above has had the LAB Color channles inverted. The behind-the-scenes tool that makes work like this possible for me is m […]

  4. […] s was a pretty straight studio shot of a bougainvillea bract. In Photoshop, I converted to LAB color. I kept a copy of the original, and inverted each channel, which I applied back in various bl […]

  5. […] nding modes. My own cross-processing technique is complicated, and starts with the use of LAB color. I plan to explain some of the details of the process in a future story. Related links: Phot […]

  6. […] 8217;s what I did. I took a duplicate of the center component exposure and converted it to LAB color. Next, I inverted the luminosity channel to come up with a reverse image of the white strip ( […]

  7. […] otated version of itself. The mild Photoshopping consists of blending the original with a LAB color inversion of itself using the Multiply belnding mode at a low opacity and a layer mask (creat […]

  8. […] cessed this image from Camera RAW using my normal workflow to reduce noise and selectively enhance luminance and radiance (this story will give you an idea of what I mean by enhancing radiance). […]

  9. […] create an appropriate mask by converting a duplicate of the darker version of the image to LAB color. Next, I dropped the A and B channels of the image, leaving just the luminosity information. […]

  10. […] s, plastic gnomes, wishing wells, or pink flamingos in their garden… Read more. Post 598: I’ve been reading Dan Margulis’s masterful Photoshop LAB Color: The Canyon Conundrum an […]

  11. […] ted part of our garden, first on white, then via an inversion of the Luminosity channel in LAB color, on black. By the way, the original Photoshop files for these two images are huge, each a b […]

  12. […] ted part of our garden, first on white, then via an inversion of the Luminosity channel in LAB color, on black. By the way, the original Photoshop files for these two images are huge, each a b […]

  13. […] on the image in Photoshop using a variety of blending modes with duplicated inversions of LAB channels. […]

  14. […] on a light box using a macro lens and extension tube. In Photoshop, I converted the image to LAB color. Next, I inverted the image (to get the black background) and combined the inversion with the […]

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