14 January 2010

[photoshop] Into The Blending Modes With Gun And Camera, Part 2: The Contrast Modes

2298.In the last missive in this series, we reviewed the top three groups on Photoshop's layer blending modes list: Normal (Normal and Dissolve), Darken (Darken, Multiply, Color Burn, and Linear Burn), and Lighten (Lighten, Screen, Color Dodge, and Linear Dodge).

The section after this, comprising seven modes starting with Overlay and ending in Hard Mix, are known as the Contrast modes, because the modes cause colors in the base and/or blend layer to darken or lighten, thus increasing the contrast. The measuring point is the value of the blend layer or color; usually here, lightening happens in some way if the blend is brighter than 50% gray, and darkening happens if they blend is darker than 50% gray. The principal difference between the modes seems to be how each accomplishes that.
  • The first mode, Overlay, allows the upper layer (blend layer) to overlay the lower layer (base layer), multiplying or screening the color depending on the base layer. This has the effect of maintaining the highlights and shadows of the base layer. According to Photoshop Help, the base color is not replaced but mixed with the base color to reflect the lightness or darkness of the base color.
  • Soft Light makes the blend layer kind of behave as a light source. The color is lightened or darkened depending on the blend layer. As a result, the image looks as though you're shining a soft spotlight on it. From Photoshop Help: If the blend color (light source) is lighter than 50% gray, the image is lightened as if it were dodged. If the blend color is darker than 50% gray, the image is darkened as if it were burned in. Painting with pure black or white produces a distinctly darker or lighter area, but does not result in pure black or white.
  • Hard Light works differently, of course; whereas the Soft Light blend lightens or darkens, Hard light multiplies or screens the color, depending on the blend layer. The effect is as though you're shining a harsh spotlight on the image. If the blend is lighter than 50% gray, it's lightened as though screened; if the blend is darker, it's darkened as though multiplied. This is useful for adding shadows to an image. Painting with black or white results in pure black or white.
  • Vivid Light burns or dodges the images by increasing or decreasing the brightness, depending on the blend layer. Blends (the light source) brighter than 50% gray result in a lightening of the image by decreasing the contrast, and darker than 50% gray are darkened by increasing the contrast.
  • Linear Light works as Linear Light does, but where Vivid darkens or lightens the image by changing the contrast depending on the blend, Linear Light darkens or lightens image by changing the brightness depending on the blend. Again, the cutoff is at 50% gray.
  • Pin Light actually replaces the colors, depending on the blend color. If the blend layer is lighter than 50% gray, pixels that are darker than the blend are replace where those lighter are left alone. If the blend is darker than 50%, the lighter pixels are the ones that are replaced.
  • Hard Mix is the most radical of this group. Remember that the RGB digital values can range from 0 to 255. Hard Mix adds the RGB channel values of the blend layer to the base layer; if the channel result is greater than 255, then that channel is set to 255; if it's less, the channel is set to 0. As a result, all pixels are changed to primary colors: red, green blue, cyan, yellow, magenta, white, or black.
These blending modes are a little hard to explain; I depended on Photoshop Help and tried to rephrase them a little better, with alternative success. Now, one can begin to see why a lot of Photoshoppers it's a process of trial and error.

In the next chapter of this exploration, I'll try and increase my own understanding of this by actually blending layers and examinging the results; along the way, we'll get to the next group, the Comparison modes, comprising Difference and Exclusion, and try to make some sense out of those.

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