sci-vis What the research was showing, and why you could not see it

Palettes

These are the only colours used on this site. They are free to take, in the forms you actually need them in: a hex list to paste, and a lookup table to drop into Fiji. No sign-up, no email, and they will stay at this address.

Categorical

For discrete groups. Every entry carries a shape and a dash pattern as well as a hue, because colour on its own should never be the only thing telling two series apart. Roughly one man in twelve has some form of colour-vision deficiency, and nobody at all can read a hue in a photocopy.

sci-vis default

The default for discrete groups. Six hues, searched rather than chosen, so that no two stay closer than OKLab dE 9.5 under any common colour-vision deficiency and every one is legible as a hairline.

  1. #0a96d6 azure circle, solid
  2. #cb1043 crimson triangle, dashed
  3. #23690d moss square, dashed
  4. #923dfb violet diamond, dashed
  5. #c4780b amber cross, dashed
  6. #8c0779 plum star, dashed

Hex list

okabe-ito

The published Color Universal Design set. Use it where a reader already knows it, or where matching an existing figure matters. Its yellow is too faint for a thin line on a pale background.

  1. #0072b2 blue circle, solid
  2. #d55e00 vermillion triangle, dashed
  3. #009e73 bluish green square, dashed
  4. #cc79a7 reddish purple diamond, dashed
  5. #e69f00 orange cross, dashed
  6. #56b4e9 sky blue star, dashed
  7. #f0e442 yellow wye, dashed
  8. #000000 black plus, dashed

Hex list

Sequential and diverging

For continuous quantities. All four are monotonic in lightness, which is what makes them readable in greyscale and what a rainbow map is not. Every palette on this page, categorical and continuous, is screened on each build against simulated protanopia, deuteranopia and tritanopia, and the result of that screening is committed to the repository rather than asserted here.

viridis sequential

Perceptually uniform and monotonic in lightness, so equal steps in the data look like equal steps on the page and it survives being printed in greyscale.

Fiji lookup table · #440154 #3b528b #21918c #5cc863 #fde725

cividis sequential

Built so that a deuteranopic reader and a normal-vision reader see the same structure. Prefer it over viridis when the colour scale is carrying the argument.

Fiji lookup table · #002051 #3d4d6e #807c75 #bbae71 #fdea45

puor diverging

Purple to orange, for signed data with a meaningful zero. Colourblind-safe, unlike the red-to-blue map most software defaults to.

Fiji lookup table · #2d004b #998fbf #f3eeea #ee9d3e #7f3b08

brbg diverging

Brown to blue-green. The second diverging pair, for when purple and orange collide with a categorical series on the same page.

Fiji lookup table · #543005 #cfa256 #edf1ea #5cb2a8 #003c30

Using the lookup tables in Fiji

Save the .lut file, then in Fiji choose Image, Lookup Tables, Open, and pick it. It will appear in the Lookup Tables menu from then on. These are NIH Image text LUTs, three columns of red, green and blue over 256 rows, so you can read one in a text editor and check it yourself.

If you are choosing between them: use cividis when the colour scale is carrying the argument, and viridis otherwise. Cividis was built so that a reader with deuteranopia and a reader without see the same structure, which viridis does not quite manage.

Hannah Isles takes on figure and manuscript work through Hannah Isles Editorial. Hannah Isles Editorial