Color conversion can be a tricky prospect and so there are a couple of things that should be kept in mind when using Colorwise and the colors that it produces.
The color space is device dependent RGB. This means that color information is acquired as values of red, green and blue.
Since light-produced colors, such as those on a computer are additive, when colors are mixed, they approach white with higher values and black with lower values. A color 100% red, 100% green and 100% blue would be white and a color 0% red, 0% green and 0% blue would be black.
In contrast, printing works in a different manner and is generally represented in the CMYK color space.
Most people remember studying the color wheel when learning to paint as a child, the primary colors were red, yellow and blue. This is roughly magenta, yellow and cyan. When these colors were mixed with paint, they are subtractive and produce darker colors, generally a brown.
When looking at complimentary colors it is necessary to keep in mind that the result of mixing colors in an additive or subtractive color space will result in different compliments. In painting, the compliment of red is green, in light and RGB it is cyan.
For a demonstration on the effects of complimentary colors on the eye, see Complimentary Color Effect.
Since Colorwise uses RGB to gather information about color, conversions start with RGB and are converted to other formats.
Notes on CMY & CMYK
The color spaces are generally used for colors that will be used in print. Since these are popular color spaces, they have been included for basic color printing. The differences between CMYK devices are influenced by paper, ink and printer technology. For professional purposes printer profiling is recommended.
Notes on HSB and HSL
There is no standard that defines these calculations. Simplified equations are included, however hue is not linear and lightness does not match color vision. RGB - CMY (RGB values from 0 - 1.0)
C = 1 - ( R / 1.0 )
M = 1 - ( G / 1.0 )
Y = 1 - ( B / 1.0 )
CMY - CMYK
black = 1
if ( C < black )
black = C
if ( M < black )
black = M
if ( Y < black )
black = Y
if ( black = 1 )
C = 0
M = 0
Y = 0
else
C = ( C - black ) / ( 1 - black )
M = ( M - black ) / ( 1 - black )
Y = ( Y - black ) / ( 1 - black )
K = black
RGB - HSB (RGB values from 0 - 1.0)
min = MIN(R,G,B)
max = MAX(R,G,B)
delta = max - min
V = max
if ( delta = 0 )
H = 0
S = 0
else
S = delta / max
deltaR = ((( max - R ) / 6 ) + ( delta / 2 )) / delta
deltaG = ((( max - G ) / 6 ) + ( delta / 2 )) / delta
deltaB = ((( max - B ) / 6 ) + ( delta / 2 )) / delta
if ( R = max )
H = deltaB - deltaG
else if ( G = max )
H = ( 1 / 3 ) + deltaR - deltaB
else if (B = max )
H = ( 2 / 3 ) + deltaG = deltaR
if ( H < 0 )
H = H + 1
if ( H > 1 )
H = H - 1 RGB - XYZ (RGB values from 0 - 1.0)
Observer = 2º, Illuminant = D65
if ( R > 0.04045 )
R = (( R + 0.055 ) / 1.055 )2.4
else
R = R / 12.92
if ( G > 0.04045 )
G = (( G + 0.055 ) / 1.055 )2.4
else
G = G / 12.92
if ( B > 0.04045 )
B = (( B + 0.055 ) / 1.055 )2.4
else
B = B / 12.92
R = R * 100
G = G * 100
B = B * 100
X = R * 0.4124 + G * 0.3576 + B * 0.1805
Y = R * 0.2126 + G * 0.7152 + B * 0.0722
Z = R * 0.0193 + G * 0.1192 + B * 0.9505
XYZ - CIE-L*ab
Observer = 2º, Illuminant = D65
X = X / 95.047
Y = Y / 100
Z = Z / 108.883
if ( X > 0.008856 )
X = X(1/3)
else
X = ( 7.787 * X ) + ( 16 / 116 )
if ( Y > 0.008856 )
Y = Y(1/3)
else
Y = ( 7.787 * Y ) + ( 16 / 116 )
if ( Z > 0.008856 )
Z = Z(1/3)
else
Z = ( 7.787 * Z ) + ( 16 / 116 )
L = ( 116 * Y ) - 16
A = 500 * ( X - Y )
B = 200 * ( Y - Z )
XYZ - Hunter Lab
hL = 10 * √Y
hA = 17.5 * ((( 1.02 * X ) - Y ) / √Y )
hB = 7 * (( Y - (0.847 * Z )) / √Y) Acknowledgements
Resene Color Library
Resene RGB Values List
"For further information refer to http://www.resene.co.nz"
"Copyright Resene Paints Ltd 2001"
"Permission to copy this software, to modify it, to redistribute it, to distribute modified versions, and to use it for any purpose is granted, subject to the following restrictions and understandings."
"1. Any text copy made of this dictionary must include this copyright notice in full."
"2. Any redistribution in binary form must reproduce this copyright notice in the documentation or other materials provided with the distribution."
"3. Resene Paints Ltd makes no warranty or representation that this dictionary is error-free, and is under no obligation to provide any services, by way of maintenance, update, or otherwise."
"4. There shall be no use of the name of Resene or Resene Paints Ltd in any advertising, promotional, or sales literature without prior written consent in each case."
"5. These RGB colour formulations may not be used to the detriment of Resene Paints Ltd."