The problem with color to grayscale

using a straight conversion in Photoshop


Hue & Saturation are useless values in color to grayscale conversion.
Only the Brightness Luminosity is of use. Color to GRAYSCALE contents for more information

In Lab color mode the Lightness channel is Luminosity very useful! extract this as a simple conversion. It might need adjusting (darkening) with Levels as it produces as it says Lightness Channel.


Hue: is one of the main properties of a color described with names such as “red”, “yellow”, etc. The two other main properties are lightness and colorfulness. Hue is also one of the three dimensions in some colorspaces along with saturation, and lightness

Saturation: which is the amount of gray in a particular color. A color with more gray is considered less saturated, while a bright color, one with very little gray in it, is considered highly saturated. The amount of saturation does not affect the basic hue of a color and it also is unrelated to the value (amount of light or darkness in a color.) For example, if we take away the colors in an image, the tonal values will remain. However, taking away the colors themselves will make the image completely unsaturated. A more saturated color is also called a more ‘pure’ color because it is undisturbed by gray.

Luminosity: relative brightness of something.


Color to Grayscale

Notice how the 4 colors on the left convert to 2 shades of gray!


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