14 October 2008

Photoshop Layer Blending Modes: Normal, Darken, Lighten


Working the last few tutorials has again reminded me how useful Photoshop's blending modes are. However, when I was trained in PS, I wasn't given a very deep understanding of them. The modes were used in a trial-and-error fashion, which, for a beginner, was kind of a relief ... the list can be eye-glazing to the tyro.

However, for long-term artistic development, one really wants to have a somewhat deeper understanding of what blending modes (with their odd names) mean. Along the way, and from various sources, I've made my own list. It's a work in progress, but it helps me a bit.

Knowing which tool to use improves your workflow; you save yourself the trial-and-error step and go straight to tweaking the mode.

The blending modes in PS are divided into a handful of groups, which are related by the general effect they have on the pixels they govern. In the following, I use three terms: base color is the original color in the image, blend color is the color that's being applied with the editing tool, and result color is the color that, of course, results.

 Herewith the list, divided by groups:

The Normal Group: causes no fundamental change to the pixel's color values

  • Normal Normal blending is just what it says; the normal mode of operation. To be specific, any painted pixel on a layer above simply covers up any pixel below it. This is the default.

  • Dissolve This one I don't use much. On a layer with a faded edge, Dissolve randomly replaces the pixel color with the blend color, depending on the opacity of the location. On something with a soft, blurry fade, Dissolving with another layer will turn it into a choppy, noise-y sort of thing. If you drop layer opacity below 100%, Dissolve will dither all pixels.

The Darken Group: Blends the pixels on the active layer to a darker color depending on the setting.

  • Darken The result of this is the blend color or the base color, whichever is the darker one. If the pixel is lighter than the blend color it's replaced; if not, no change.

  • Multiply Mathematically multiplies the two colors together; the result is the new blend. Multiplying any color by black will give you black; multiplication with white produces no change. Paint with this mode active and get darker and darker colors with each successive stroke.

  • Color Burn darkens the base color to reflect the blend color by increasing the contrast. I'm not too clear on what that verbiage means, but the result is what one site calls "crisp, toasty" colors. They look rich, warm, and overexposed.

  • Linear Burn darkens the base color to reflecting the blend color by increasing the brightness. The result is less lurid and smoother than Color Burn.

The term "Burn" comes to us from the photographer's darkroom, where an area of a negative was overexposed by by screening out the light all around. The Photoshop Burn tool icon itself reflects this heritage: the hand forming an aperture just so was a common way photographers isolated a burn.

The Lighten Group: Blends the pixels on the active layer to a lighter color depending on the setting.

  • Lighten replaces the base color with either the base color or the blend color depending; pixels darker than the blend color are replaced, and pixels lighter are not.

  • Screen mathematically inverts the colors, multiplies them, then inverts them again. The result is usually a lighter image. The name is wholly non-intuitive.

  • Color Dodge with the dodge modes we once again return to the darkroom. Dodging an image was the opposite of burning an image; instead of isolating an image for more light, the photographer used a paddle-shaped tool with a wire handle to block out the light, resulting in a lighter area. Similar to Color Burn, Color Dodge lightens the base to reflect the blend by decreasing the contrast. Each color becomes a value-brightness multiplier; black drops out entirely.

  • Linear Dodge Lightens the base color to reflect the blend by decreasing the brightness. Gives a smoother effect than Color Dodging.

We'll treat the next groups, Light, Invert, and Color blending modes, in the next missive.

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