I love gradient maps. I really, really love gradient maps. You should, too, because they’re insanely flexible, accurate and easy to work with.
For those unfamiliar with Photoshop’s gradient map adjustment layers, here’s how they work: Imagine a photo in greyscale. Being greyscale, it can only contain black pixels, white pixels, or pixels that are shades of grey.
Now imagine that instead of being shades of grey from black to white, the lightest parts of the image are yellow, and the darkest parts are red, with a smooth blend of oranges in between. That’s a gradient map.
Gradient maps use brightness to assign corresponding colours taken from a gradient of your choice. In the example above, it was a gradient from yellow to red, but gradients can contain many points, too.
The colour and position of the points in the gradient map gradient can be used to control contrast and brightness, as well as colour.
Gradient maps have been around since Photoshop 4 (that’s version 4.0, released in 1996, not the more recent CS4), so they’re far from new, but I feel like they’re one of the most powerful features in Photoshop when working with colours.
Adding a gradient map
Gradient maps can be added via the adjustment layer icon in the layers panel.
Accurate and absolute
Most adjustment layers in Photoshop are relative — make the image brighter, or more blue, or higher contrast, or less saturated. Gradient maps deal in absolutes — you get to set the exact colours that are used. And, being absolute, gradient maps can’t push colours outside the normal range (0-255 for 8bit), so accidental clipping won’t occur.
Gradient maps can also let you create effects that would take several other adjustment layers to achieve, lowering the chance of rounding errors, which typically manifest as gradient banding. More control, more precision, less layers, less banding.
Being an adjustment layer, gradient maps can be applied to many things at once and contained within clipping groups, which is insanely handy — it’s possible to build a complex composition of gradients and effects, then colour them with a single gradient map adjustment layer. As an added bonus, working that way also lets you easily replicate the same colour treatment to different elements in your document or different documents.
I really, really love gradient maps.
Published 18 March 2013.