To help you make sense of the most recent episode of dekePod, I’ve written up a discussion of how I modified the colors of my backyard in the Lab mode. Although it flies by in the video, the technique is not particularly difficult. I don’t use Curves or masking or anything terribly complicated. Just Levels and — brace yourself — Brightness/Contrast. In Photoshop CS3, Brightness/Contrast has not only turned into a respectable command, but it has been elevated to pro status when combined with Lab. And it remains as easy as ever to use.
Some portions of this article have been excerpted from my upcoming article, “Don’t Fear the Lab Mode,” which will run in the September, 2008 issue of Photoshop User magazine. So as not to diminish the impact of that article (as well as the two that will follow it), I have purposely made the steps here brief, illustrated with thumbnail-resolution imagery. You should still be able to follow along, but you’ll have lots more to look forward to in Photoshop User.
Step one: Open an image
One that needs help. I reckon this low-contrast photo of my backyard qualifies. There’s even a smudge on the window and twigs in the way. Gosh I’m good.
Step two: Switch to Lab
Choose Image > Mode > Lab Color. The result is an image with three channels: Lightness, a, and b. Lightness conveys luminance. As diagrammed below, a controls tint and b controls temperature.
Step three: Fix a and b with Levels
Add a Levels adjustment layer. Skip Lightness and switch to the a channel. Apply symmetrical adjustments to increase color contrast and boost saturation. I raised the black point to 8 and reduced the white point to 175 (255 minus 80). Next go to the b channel and repeat the process.
Step four: Tweak the values
My photograph suffers from a slight bluish color cast. To compensate, I reduced the white point in the b channel to 172. A little lavender remained, so I went to the a channel and increased the black point to 81. Click OK.
Step five: Blend away any aberrant colors
The reds and oranges in the wood and bricks are too hot. To pull them back, I right-clicked on the Levels layer and chose Blending Options. I chose a from the Blend If pop-up menu and dragged the white point for This Layer to 150. Then I pressed Alt (or Option) and dragged the right half of the white point to 210. I repeated the process for the b channel and clicked OK.
Step six: Apply Brightness/Contrast
To address the Lightness channel, add a Brightness/Contrast adjustment layer. I went with Brightness and Contrast values of +20 and +40, respectively, to achieve the more cheerful image below. Click OK to apply.
What makes Brightness/Contrast so well suited to Lab? It invariably affects just the Lightness channel; it can’t even see the contents of a or b. Plus, its controls have been dramatically improved in Photoshop CS3 so the command no longer clips shadows or highlights.
If you compare the first image to the last, you’ll see that we’ve made a lot of progress. But our work is not done. In future editions of my regular Deke Space column for Photoshop User magazine, I’ll show you how to sharpen the image using smart filters, smooth away color noise, and resolve chromatic aberrations by working within Lab and around it. Finally, we’ll apply a panoramic crop to achieve the result pictured below. It all takes us into more advanced territory, but the results justify the effort.
You can also learn about this technique in my video series Photoshop CS3 Mastering Lab Color, available from lynda.com. Specifically, check out the 11-movie Chapter 3, “A Typical, Nondestructive Lab Correction” which takes this image from its wretched beginning all the way to its panoramic end.
Great tips
Great thanks
lab on
Deke
Yah! Thanks so much for taking the time to write the info down.
keith
www.thephotoshopguy.net
Lab = HSB? = HSL?
So… in Lab, lightness conveys luminance and a controls tint and b controls temperature.
Sounds an awful lot like the HSB (Hue, Saturation and Brightness) color mode used in Fireworks and Illustrator’s Color Palette as well as the HSL (Hue, Saturation and Lightness) values in Photoshop’s Hue/Saturation command.
Lab:__________HSB, HSL:
Lightness______Brightness, Lightness (luminance)___(same?)
Tint __________Hue___________________________(same?)
Temperature___Saturation (chroma, purity)__________(different?)
Are these color modes the same or only have some similarities? Or am I missing something?
p.s. That’s a REALLY nice color wheel. Thanks! Per your advice, I already have your color wheel from Photoshop 1 on 1 on my wall in my classes and in my office. This will join it.
Thanks! and Go Team USA! :-)
Thomas
Thomas Benner
Austin, Texas
http://www.masteradobe.com
The wild and wacky world of Smart Objects
Ok, I don’t know how many of you had the chance to view Deke’s LAB session on Lynda.com, but he put out a call to action: “How many of you would like to see a course on the wild and wacky world of Smart Objects?” I for one would definitely like to see that. There’s so much more to it than the obvious non-destructive scaling and proprietary updating.
How ‘bout it Deke. Any plans for a video/podcast on Smart Objects?
steve_zimmer
They’re all different
One way to understand how it works is to click on a swatch at the bottom of Photoshop’s toolbox to bring up the Color Picker dialog box. Notice you have HSB radio buttons on left and Lab on right. Select B. You’ll see a rainbow of hues at the top of the square field on left declining into gray at the bottom. You also have a vertical gradient with slider triangles. Move the sliders all the way to the top to see the most vivid hues declining to white at bottom. (If this were HSL as opposed to HSB, setting L to white would turn the whole field white; the brightly saturated hues occur at L: 50%.) Move the slider down to black and the whole field turns black. (That’s the way it is for HSL, too.)
Now select the L in Lab. Move the gradient triangles to half mast—50% gray. There are all of your colors at full intensity around the perimeter, declining to gray in the center. (Radial projection this time.) Now move the triangles up and down. You never lose color. Amazingly, even at full Lightness and no Lightness, colors survive. That’s where those imaginary colors come into play—galactic falafel, sinister pine cone, and the rest. These are colors (with made-up names, of course) that have no chance in hell of reproducing in RGB or CMYK. (They won’t disappear, they’ll just clip.). It’s fairly fascinating stuff.
So, to answer your question, a and b are color axes that intersect at 90 degrees. The intersection is 0% saturation, the farther you move out from the intersection, the more intense the hues get. With Hue and Sat, all colors are functions of Hue, while Saturation controls their intensity.
If this is something people are interested in, I can write it up with a few illustrations.
BIG color diagram
Just for larffs, and as a special thanks to those of you who are members, I’ve added a magnified version of the Lab color diagram. Just click on the embedded color diagram above and you’ll get another one sized to 1200 by 1200 pixels. Feel free to print and share. Credit is always welcome.
I should mention that, while the JPG provided here is RGB (JPEG doesn’t support Lab), the diagram was created fully in Lab and the values listed are point accurate. Also, I engineered the diagram so that the shift from Lab to RGB was minimal.
Enjoy!
Thanks for the Lab, HSB, HSL Stuff
Thanks for your valuable time and assistance with the in-depth answer Deke.
You clearly communicated the distinctions between all three in your reply with useful “behind the scenes” details as I so enjoy in your books and videos. You continue to teach this teacher about the art of teaching.
The earlier “tint” and “temperature” Lab descriptions sort of threw me and I expected I was missing something somewhere.
Sorry if it took up a lot of your time,
Live long and prosper Senor!
Thomas
p.s. Let me check: In paragraph 1, sentence 1, I think you mean “...click on a grey swatch…” so that grey shows up at the bottom of the square field when B is selected. Right?
Thomas Benner
Austin, Texas
http://www.masteradobe.com
Thank You
That is very considerate of you. Thank you Deke for your valuable time and brain energy to provide this. It’s appreciated.
Oh… you are always credited in my classes for providing the color wheels and so much more. My students hear me preach my “Photoshop trinity”... Deke, Bert and Russell at almost every session :-)
Thomas
Thomas Benner
Austin, Texas
http://www.masteradobe.com
Curves vs Levels
Deke,
Anytime I see a blog post where I get to use levels instead of curves I’m there.
“I don’t use Curves or masking or anything terribly complicated. Just Levels.”
I can’t figure out curves. It’s a very cool adjustment. Everyone seems to use it. You get to makes those little points, bend the curve and make cool patterns in the graph. Only one problem for me: It makes the photo look worse.
Levels is simple and just seems to work. I will definitely try it out with lab color. Thanks for the more detailed explanation.
Robert
http://www.photographyandthemac.com
Thanks!
Deke.. thanks so much for showing me the light. I don’t think I would have ever gotten around to using Lab if I hadn’t found this article. This is almost as exciting as when I learned why RAW is so great!
Lab Mode
Hi Deke
So nice to find info on Lab Mode as it is a subject well hidden by other authors. or not mentioned.
I imagine that it is similar in CS5
Thank you for sharing
Gus
Merci pour les instructions
Merci pour les instructions détaillées! J’ai suivi vos conseils et maintenant commence enfin à gagner non seulement jouer aux casino en ligne! Merci!
Lab inside a smart object?
Hi Deke! I’d like to ask about using Lab but, first, some heart-felt praise; I’ve been using Lynda.com for about a year now and your tuition is the most easy-to-follow and entertaining by ‘a country mile’ as they say on your side of the pond.
Here it is: I noticed that when you use Lab to correct images you will switch back to RGB afterwards. Would it not be even better to change the layer into a smart object and alter Lab inside that smart object? Thereby having an RGB file wtih a Lab-mode smart object inside it? So you’re essentially using non-destructive Lab corrections?
Please impart your wisdom, that I might save memory space etc that I’m probably wasting by working this way.
Many thanks and best wishes Deke - your teachings are absolutely first class
- Ben, UK