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---- What are the web colors most comfortable to users?

MarkFilipak - 10:23 pm on Mar 16, 2008 (gmt 0)

From [w3.org...]
 Two colors provide good color visibility if the brightness difference and the color difference between the two colors are greater than a set range. Color brightness is determined by the following formula: ((Red value X 299) + (Green value X 587) + (Blue value X 114)) / 1000 Note: This algorithm is taken from a formula for converting RGB values to YIQ values. This brightness value gives a perceived brightness for a color. Color difference is determined by the following formula: (maximum (Red value 1, Red value 2) - minimum (Red value 1, Red value 2)) + (maximum (Green value 1, Green value 2) - minimum (Green value 1, Green value 2)) + (maximum (Blue value 1, Blue value 2) - minimum (Blue value 1, Blue value 2)) The rage [sic] for color brightness difference is 125. The range for color difference is 500.

The first formula is not brightness. It is luminance.
The standard formula for luminance is: luma = 30% red + 59% green + 11% blue. This is a little easier to remember than what the W3C supplies and is accurate to 8 parts in 1000 (i.e., 0.8%).

I have real problems with the second formula. The values for red, green, and blue are absolute but the datatype is not specified. Are they integers? longs? floats? Of course, this has a huge implication when it is stated that "The [minimum] range for color difference is 500". Without any clue regarding the span of color value, the number "500" is meaningless. What is needed is the formula for color vector (using the familiar color wheel). A relative difference in color angle would yield something more meaningful than "500". But the color angle would not, by itself, provide a comprehensive metric.

We have about 4 times the color discrimination in orange as we do in blue -- we can 'see' a difference in two orange hues that are separated by a color angle of only about one-quarter of the minimum angle at which we can 'see' a difference between two blue hues.

So, a weighted color angle is what's needed. That's what the Munsell color system is all about.

To the Munsell color space, we must factor in the various flavors of color blindness (actually, hue discrimination deficit).

In the final determination, an algorithmic determination of readability must compare two points in a modified, 3-dimensional Munsell color space -- modified to account for hue discrimination deficit. Until the engineers at the W3C start talking to people outside their group, and until they incorporate well known principles worked out by the television industry 70 years ago, this issue will remain subjective and is not to be taken seriously. In other words, if you use the W3C recommendations, your mileage may vary.