Brightness vs Luminance/luminosity.
Apr 7, 2021 22:50:26 #
They are not the same thing
The brightness of a color is set by using the start of the Hue (pure color) toward black.
Luminance or luminosity is a grayscale going from Black to white.
Luminance is related to brightness, but it is literally half the story.
The other half is saturation. Saturation is set using the Hue (pure color) toward white.
Luminance or luminosity adjustment is really White - Hue - black.
So why is a color is reduced to grey when saturation is pushed to its limit?
Simply because the color is replaced by it greyscale value.
Black, white and grey are not influenced by a reduction in saturation because all three channels that compose them are of equal measure. Brightness on the other hand will modify them but not the equality between the channels. A white can go all the way to black, Grey can go either to white or black and black can go all the way to white.
The brightness of a color is set by using the start of the Hue (pure color) toward black.
Luminance or luminosity is a grayscale going from Black to white.
Luminance is related to brightness, but it is literally half the story.
The other half is saturation. Saturation is set using the Hue (pure color) toward white.
Luminance or luminosity adjustment is really White - Hue - black.
So why is a color is reduced to grey when saturation is pushed to its limit?
Simply because the color is replaced by it greyscale value.
Black, white and grey are not influenced by a reduction in saturation because all three channels that compose them are of equal measure. Brightness on the other hand will modify them but not the equality between the channels. A white can go all the way to black, Grey can go either to white or black and black can go all the way to white.
Apr 7, 2021 23:55:54 #
Selecting a color in PS CC and using the HSL adjustment shows the difference between brightness and luminosity/luminance/lightness
Arrows:
Black = Saturation (Hue to white)
Pink = Brightness (Hue to Black)
Yellow = Hue slider
Note:
► When the color is pure (Maximal Saturation and Brightness) Only two RGB channels are used to define it.
→ Master channel is unchangeable (R, G or B)
→ Secondary channel changes.
► Any change of the probe to the left brightens the image up to white (saturation)
► Any change of the probe to toward the bottom it darkens the image up to black (brightness).
► This is reflected in the HSB values as a change in percentage in either S or B. Any motion within the X/Y axis will change both S and B values.
Any change in saturation or brightness remove the 'pure' qualification of the Hue: More than two channels are used to create the shade.
HSL adjustment:
Desaturating will give you a shade of grey to an oversaturated color shade.
Changing the luminosity goes from White to Black
Arrows:
Black = Saturation (Hue to white)
Pink = Brightness (Hue to Black)
Yellow = Hue slider
Note:
► When the color is pure (Maximal Saturation and Brightness) Only two RGB channels are used to define it.
→ Master channel is unchangeable (R, G or B)
→ Secondary channel changes.
► Any change of the probe to the left brightens the image up to white (saturation)
► Any change of the probe to toward the bottom it darkens the image up to black (brightness).
► This is reflected in the HSB values as a change in percentage in either S or B. Any motion within the X/Y axis will change both S and B values.
Any change in saturation or brightness remove the 'pure' qualification of the Hue: More than two channels are used to create the shade.
HSL adjustment:
Desaturating will give you a shade of grey to an oversaturated color shade.
Changing the luminosity goes from White to Black
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