TfL has a bit of a history of poor choices for the colour of services, Overground as a shade of orange that’s easily confused with the red of buses and the light orange of the coaches. Then there’s the confusion around red for buses and blue for TfL (and red and blue for Underground). Have a look at the roundels at the bottom. With colour playing such a huge roll in the sub-brands of services there really should be are more careful approach to the whole thing.
And now there’s cycle hire.
The new scheme takes its colour (apparently) from the main sponsors Barclays Bank. The only problem is that the colour is already used for river services:
this is the way the W3C calculate the brightness of colours on screen, while entirely tailored to the world of RGB screens and hexadecimal codes it does suggest a more rigorous approcah to analysing colour combinations. Anyhting that removes the apparent personal taste of a designer is obviously going ot be useful in any information design context. Here’s the science bit:
Ideally, images and multimedia object should also be tested for color visibility but algorithms are beyond the scope of this specification.
Color visibility can be determined according to the following algorithm:
(This is a suggested algorithm that is still open to change.)
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 for color brightness difference is 125. The range for color difference is 500.
Here’s the original article: http://www.w3.org/TR/AERT#color-contrast