FlowingData Forums » Data Visualization

Choosing Colour Ranges

Started 3 years ago by kevincannon / 6 posts

  1. kevincannon
    Member
    Posted 3 years ago #

    Hey all,

    I'm just wondering what approaches you take to choosing colour ranges in visualization work? One of the main things I use is Illustrator's Blend tool, which can blend between 2 colours in a specified number of steps, but that's not ideal.

    Also, what approaches do you take, do you pick 2 colurs that are beside each other on the colour spectrum, do you go from vivid to desaturated etc... and do you use any tools or do it programmatically?

    Any thoughts on this problem in general would be apprciated.

    (I've just attached an image of two different blends done in Illustrator. One just goes blue to red which is straight-forward, but the other goes blur>green>yellow which is different)

    [attachment=636,102]

  2. davidheyman
    Member
    Posted 3 years ago #

    Check out ColorBrewer at http://colorbrewer.axismaps.com/

    There's been lots of research done on this in the field of static cartography, mostly related to color perception. For sequential ramps like the one you're working on, it maxes out at 9 classes total. After that, users will have a hard time distinguishing between the colors but if you need more classes total, the blend tool should fill in the rest.

  3. nathany
    FlowingData Editor
    Posted 3 years ago #

    Thanks, david. That's what I was gonna recommend too. Good ol' cynthia brewer.

  4. dataspora
    Member
    Posted 3 years ago #

    Kevin - R has a package called 'Colorspace' that I've found to be incredibly valuable in building a variety of color maps.

    If you look in the comments of this post:

    http://dataspora.com/blog/how-to-color-multivariate-data/

    you'll find some examples of using colormap to generate iso-luminescent color ranges in the CIELAB space (that is, colors that vary only according to chroma, while maintaining equal luminance) -- like the one attached below.

    [attachment=648,104]

  5. kevincannon
    Member
    Posted 3 years ago #

    Thanks for the replies everyone - those links look interesting.

    dataspora - thanks for uploading the colormap.png file. I may ne misunderstanding that pallette, but I think that's a bad use of colour. The problem is that the colour is crossing 'across' the colour wheel, so you get this grey-ish colour in the centre. I feel that colour has too many associations of it's own; more faded out = slower/worse than the brighter colours at either end of the spectrum.

    That doesn't communicate what is desired since there's not a natural mapping. Compare it to the image i've attached, where the colour has a more direct relation to the message.

    What do people think?

    [attachment=658,106]

  6. jsyingling
    Member
    Posted 3 years ago #

    The blend tool in Illustrator is a good place to start, but it really gets far too muddied in the middle normally. In addition, that first color scheme has too much contrast in brightness (just fully saturated and desaturated it).

    Brewers colors, however, are wonderful. I only wish there was more variety.

    [attachment=697,126]


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