Color choices for colorblind viewers

[gardnertoo]

A month or so ago I had to re-format a graph in Excel because the person for whom it was prepared is colorblind. The very distinct (to me) red and green lines on the graph were indistinguishable to him. My solution at the time was to change all the trends to black and play with heavy, light, and dashed lines to make the various trends visually different, as well as using filled-in and empty symbols, and different shape symbols. Once I had it to a point where each trend looked unique in black-and-white, I applied the colors again.

Today I stumbled upon a website which contains a suggested color palette in which each color can be distinguished from the others by people with each of the three major forms of Color Vision Deficiency (CVD). Here's a picture from the site:

The "seen by" colors do not represent an actual color seen by the CVD person. It is more of a way to demonstrate that the colors do not overlap. According to another site, when two colors are confusing to a CVD viewer, their brain makes a guess based on context. That site, which contains additional suggestions for document and presentations which are CVD-friendly (including the fact that a green laser pointer is more easily seen than the ubiquitous red laser):

http://jfly.iam.u-tokyo.ac.jp/color/

 

[SydneyGeek]

Hmmm...

Looking at the "seen by", I'm a Deutan. I find it really frustrating in presentations when reds are combined with multiple greens on screen. I see red and green as distinct colours -- no problem there. But I do have trouble picking out, say, a single red spot in a green background.
Thanks for the link!

Denis

 

[Long Nose]

Seems like a Green and Yellow would work better than Green and Red.

That is a little scary thinking about what these people must see at traffic lights. Christmas might be a little blah too.

 

[Domski]

Working for the local government in Leeds I get regular comments regarding the colours and fonts used in the reports I produce. Sometimes it can be very difficult to strike a balance between what looks good and the guidelines issued by unions (don't get me started) and other groups.

I even recently got thrown to the dogs by one guy who constantly complained about the layout of a particular report which turned out to meet all the criteria but he still made such an issue of it that the whole thing then had to be redesigned which involved considerable extra development, production and printing costs only to be reversed when a group who represented those who suffered from these afflictions proposed it was complete rubbish.

AAARRRRGGGHHHHH!!!!

 

[gardnertoo]

Here's a quick bit of code to swap in the CVD-approved color scheme in place of Excel's usual colors. Since it replaces the default colors with new default colors, the color change will be applied to existing charts if they are using the default scheme, as well as new charts created after the macro is run. I arranged the color choices to match up as closely as I could to the original colors, but had to diverge on the last few "Bar and Pie" colors, as the default scheme is heavy on variations of blue and has no green or orange.

Sub CVD_Chart_Colors()

'Replaces Excel's native default chart colors
'   with color choices which can be differentiated
'   by a viewer with any of the three forms of
'   Color Vision Defiency (colorblindness)

'Bar and Pie colors
ActiveWorkbook.Colors(17) = RGB(0, 114, 178)   'Deep blue   202°
ActiveWorkbook.Colors(18) = RGB(204, 121, 167) 'Red-Purple  336°
ActiveWorkbook.Colors(19) = RGB(240, 228, 66)  'Mustard      56°
ActiveWorkbook.Colors(20) = RGB(86, 180, 233)  'Sky Blue    202°
ActiveWorkbook.Colors(21) = RGB(0, 0, 0)       'Black         0°
ActiveWorkbook.Colors(22) = RGB(213, 94, 0)    'Vermillion   27°
ActiveWorkbook.Colors(23) = RGB(230, 159, 0)   'Tan          41°
ActiveWorkbook.Colors(24) = RGB(43, 159, 120)  'Blue-Green  160°

'Line colors
ActiveWorkbook.Colors(25) = RGB(0, 114, 178)   'Deep blue   202°
ActiveWorkbook.Colors(26) = RGB(213, 94, 0)    'Vermillion   27°
ActiveWorkbook.Colors(27) = RGB(240, 228, 66)  'Mustard      56°
ActiveWorkbook.Colors(28) = RGB(86, 180, 233)  'Sky Blue    202°
ActiveWorkbook.Colors(29) = RGB(204, 121, 167) 'Red-Purple  336°
ActiveWorkbook.Colors(30) = RGB(230, 159, 0)   'Tan          41°
ActiveWorkbook.Colors(31) = RGB(43, 159, 120)  'Blue-Green  160°
ActiveWorkbook.Colors(32) = RGB(0, 0, 0)       'Black         0°

End Sub

 

[absquatulation]

Thanks for that,

I'm going to have great fun in producing graphs and charts for which I can cause total chaos to some readers.

Errr...... Have I got the wrong end of the stick? :evil