Originally designed for color-grading film and video, Photoshop’s Color Lookup feature offers novel ways to adjust color that quickly will reveal new possibilities in your images. Capable of performing extremely complex calculations extraordinarily efficiently, color lookup tables (LUTs) work by looking up a source color in a table and using the replacement color specified in the grid to transform it for the final destination.
Like Match Color and Gradient Map adjustments (go to digitalphotopro.com to see my recent articles on Match Color and Gradient Map), the color effects Color Lookup generates are so complex, they’re not easy to previsualize. Like anything new, this takes practice. And these are new! Experiment, and you’ll find many rich possibilities. Unlike Match Color, Color Lookup is loaded with presets that will allow you to quickly explore many different effects, ones that are far more sophisticated than Gradient Map presets. In this way, using them can be as easy as using many smartphone app effects.
Color Lookup offers three types of LUTs, each with its own drop-down menu, which contains multiple presets: 3DLUT File (27 presets); Abstract (15 presets); and Device Link (5 presets) for a combined total of 47 presets. While you can only apply one Color Lookup with a single adjustment layer, you can use multiple adjustment layers to successively apply as many Color Lookups as you like. Perhaps not infinite, the possibilities are many.
What’s the difference between these three types of LUTs?
3DLUT File. Dependent on color space, 3DLUT presets load and export files with 3DL, CUBE, LOOK and CSP extensions. While Gradient Map adjustments use one channel (the grayscale values of the combined RGB channel), these lookup tables use all three color channels. They don’t generate 3D effects as the name may suggest.
Abstract. Abstract presets load and export ICC profiles. These settings aren’t color space-dependent so they maintain consistent appearances during conversions to alternate color spaces and are favored when the color space of a file is likely to change during a workflow, as it may when moving files across different output devices or to video.
Device Link. Also dependent on color space, this format is smaller and more portable than 3DLUTs.
Both 3DLUT File and Device Link presets are color space (sRGB, ColorMatch, Adobe1998, ProPhoto, etc.)-dependent and are recommended for use in the color space they were created in—all of the RGB presets were designed for use in sRGB. (LAB supports only Abstract presets. CMYK also supports Device Link, but not 3DLUT File presets.) This won’t stop you from generating impressive color effects in other color spaces. You can use many presets with color spaces other than the ones they were intended for, although the visual appearance they generate will be somewhat different. You need to keep this in mind when you’re trying to achieve consistency between different files. Be mindful that if you make a color space conversion with an active Color Lookup adjustment layer, the appearance of the file most likely will change during conversion. To get around this, you can merge the effect into a layer before making the color space conversion. Remember this when you create your own Color Lookup presets.
Get Even More Control
At first glance, you may be tempted to think that you have limited control over Color Lookup effects. You either like an effect or you don’t. Don’t move on too quickly. Take another look. You actually have lots of control. When you apply a Color Lookup table as an adjustment layer, you can modify the effect by using Opacity and/or Fill (globally reducing strength with a slider), layer masks (locally reducing strength with a brush), Blend If sliders (removing the effect from shadows and/or highlights with sliders), and Blend mode (modifying the ways color adjustments are calculated). Even with all of this control, it’s likely that you’ll want to further refine the effects of a preset with additional color adjustments using other tools like Curves and Hue/Saturation.
Make Your Own Presets
You can also generate your own Color Lookup presets. To do this, create a color effect you like with any combination of adjustments layers, Opacity and Fill, Blend If sliders and Blend modes. Note that layer masking and transparency won’t be included because alpha channel information in alpha channels isn’t included in the recipe. Then go to File > Export > Color Lookup Table, name the file, and click OK. I recommend the titles you give your presets include the color space you created them in. These files are stored in Photoshop’s Presets folder, or if they’re saved as ICC profiles, in your operating system’s Profiles folder. You can now use your custom preset at anytime on almost any file by making a Color Lookup adjustment layer and choosing your preset. You can share your custom Color Lookups with others by giving them these exported files. Color LUTs created in Photoshop even can be used in other programs such as After Effects, Premiere, SpeedGrade and other applications that use color LUTs.
Using Color Lookup adjustment layers is one way of creating a condensed layer stack, but it comes with a price—you won’t be able to adjust or mask individual adjustment layers. If you’d like to do this, as an alternative solution, you can place all of the adjustment layers into a Group and drag and drop the Group from one file into another, when needed.
If you want to produce a Color Lookup preset and achieve the greatest consistency in appearance between multiple images, you’ll want to use a file that’s representative of a majority of the images it will be used on and include a professional color chart like X-Rite’s ColorChecker. This is especially important when processing video.
Using Photoshop’s Color Lookup, you can choose to create color effects as subtle or dramatic as you like. This game-changing color-adjustment tool may seem exotic at first because it offers a new way of thinking about and seeing in color. Once you become more familiar with this mind-set, you’ll truly begin to see with new eyes. Isn’t that what it’s all about?
John Paul Caponigro, author of Adobe Photoshop Master Class and the DVD series R/Evolution, is an internationally renowned fine artist, an authority on digital printing, and a respected lecturer and workshop leader. Get PDFs and his enews Insights free on his website at www.johnpaulcaponigro.com.