maximizing keyboard label contrast


Not long ago someone posted in a thread that they had done work developing an algorithm to evaluate the contrast of labels on various HP keyboards over the years. Any information on this topic would be greatly appreciated!

Best Regards,


Well, I don't know if I'd call it an algorithm.

But, what I did at HHC2004 was to measure the color of the background and the color of the function on the background using the built-in windows paint program, which gave the color a score on RGB of 0-255 for each color.

I then did a variation of the distance between two points by :

SquareRoot of ( (R1 - R2)^2 + (G1 - G2)^2 + (B1-B2)^2 )

which gives a score of 0 (for the same color) up to about 440 for black and white.

Scores above 200 seem to provide good contrast when shown to people.

There is a link somewhere to my powerpoint presentation from HHC2004, but I dont' have it handy. It would either be at the HHC2004 website or on Jake Schwartz' site.


Exactly what I was looking for. Thanks!


Just something more to include in your analysis, from the old black-and-white TV days: There is a magnitude called "luminance", usually denoted by the "Y" letter. The luminance has to do with the graytone brightness of a given color, and with the different sensibility of the human eye to different colors. The formula

Y = 0.59 x G + 0.30 x R + 0.11 x B

gives the luminance value for a color specified by RGB values. When choosing different colors in the color space, you may also want to make them different in the luminance value; so they will be different (brighter-darker) even from a grayscale standpoint.


You might find our colour selector tool useful; it lets you wander around the space of available colours along a number of dimensions, lets you see text in relation to the colour, and lets you generate sets of colours that are maximally distinct in various ways.

It also has links to various other resources, including one on choosing colour schemes that work for colour-blind people.

Possibly Related Threads...
Thread Author Replies Views Last Post
  Another technique of HP-33S label saving x34 6 801 10-11-2012, 11:09 AM
Last Post: Luiz C. Vieira (Brazil)
  Contrast in HP42s flush display , another one.... aurelio 0 329 09-01-2012, 08:47 AM
Last Post: aurelio
  [WP 34S] Backside label contents (>> poll <<) Walter B 11 1,075 05-18-2012, 10:01 PM
Last Post: Walter B
  Rapid Reverse Branching & Label Searches Matt Agajanian 2 459 04-30-2012, 11:09 AM
Last Post: Matt Agajanian
  2nd version HP-35 with Finnish manual and back label matti 8 1,029 03-10-2012, 05:34 PM
Last Post: Gerson W. Barbosa
  Classic label reproductions? McAllan 4 582 02-27-2012, 04:58 AM
Last Post: McAllan
  Making the wp-34s label glossy Jose Poyan 5 676 02-12-2012, 12:15 PM
Last Post: Walter B
  devolution of the wp34s label---or fun with colors troy 19 2,147 02-09-2012, 02:52 PM
Last Post: Egan Ford
  HP-65/67 back label Kees Bouw 9 1,008 01-22-2012, 06:03 PM
Last Post: Michael de Estrada
  HP 27S - Adjust screen contrast? M Tulloch 2 441 07-13-2010, 02:09 PM
Last Post: M Tulloch

Forum Jump: