Heraldic Color Hatching

Combinatorial color hatching

The default "combinatorial" subtype starts from the set of five Munsell primary colors of red, yellow, green, blue, and purple plus black and white and the standard Petra Sancta color hatching system and then systematically derives additional color hatchings via three rules:

1. white + color → dashed lines
2. yellow + color → dotdash lines
3. color + color → crossing solid lines

Note: The mixed display colors shown above can be sensitive to the exact hex values chosen for the primaries. The results are fairly consistent when the primaries are the saturated, high-chroma colors typical of heraldry combined with Munsell pigment mixing but softer or more neutral primaries can shift some secondaries noticeably (for example, mixing yellow and blue can yield anything from olive-grey to muted purple depending on the blue’s hue angle).

Heraldic tincture hatching

Unicode color hatching

The "unicode" hatching subtype provides each of the hatching used in the official Unicode character chart pdfs to assign a distinct pattern to each color to render “colored” (emoji) glyphs in black-and-white. Notably Unicode has twelve different colored heart emoji (red, blue, green, yellow, purple, black, white, brown, orange, light blue, grey, pink) that each needed a separate hatching.

Okabe-Ito hatching

One of the techniques to meet Web Content Accessibility Guidelines (WCAG) is to use color and pattern to ensure things are accessible to the color-blind.

The Okabe-Ito palette is a widely used colorblind-friendly palette. Here is an example of adding a simple hatching scheme to go with this palette to provide visual redundancy:

• “yellow”, “blue”, and “white” are given their standard Petra Sancta hatchings
• “reddish purple” is given a “purple” Petra Sancta hatching
• “bluish green” is given a “green” Petra Sancta hatching
• “vermillion” (red orange) is given a “red” Petra Sancta hatching
• we use a simple black fill for “black” instead of a “sable” crosshatch
• “orange” and “sky blue” are given the hatchings from German heraldry (see Fox-Davies’ section above)

oi_names <- c(
    "black", "orange", "sky blue", "bluish green",
    "yellow", "blue", "vermilion", "reddish purple", "white"
)
oi_hex <- c(
    "#000000", "#E69F00", "#56B4E9", "#009E73",
    "#F0E442", "#0072B2", "#D55E00", "#CC79A7", "#FFFFFF"
)
oi_hatch <- c(
    NA, "orange", "bleu celeste", "vert",
    "or", "azure", "gules", "purpure", NA
)
sx <- c(0, 0, 1, 1)
sy <- c(1, 0, 0, 1)
n <- length(oi_names)

grid.newpage()
grid.rect(gp = gpar(fill = "white", col = NA))
pushViewport(viewport(width = 0.90, height = 0.94))
grid.text(
    "Okabe-Ito Palette with Heraldic Hatching",
    y = unit(1, "npc") - unit(0.25, "cm"),
    just = "top",
    gp = gpar(fontsize = 13, fontface = "bold")
)
pushViewport(viewport(
    y = 0.46, height = 0.88,
    layout = grid.layout(
        n, 3,
        widths = unit(c(3, 2.5, 4), "null"),
        heights = unit(rep(1, n), "null")
    )
))

for (i in seq_len(n)) {
    grid.text(oi_names[i], x = 0.90, just = "right",
              gp = gpar(fontsize = 12, col = "black"),
              vp = viewport(layout.pos.row = i, layout.pos.col = 1))

    grid.text(oi_hex[i],
              gp = gpar(fontsize = 12, fontfamily = "mono", col = "black"),
              vp = viewport(layout.pos.row = i, layout.pos.col = 2))

    pushViewport(viewport(layout.pos.row = i, layout.pos.col = 3))
    grid.rect(gp = gpar(fill = oi_hex[i], col = "black", lwd = 3.0))
    if (!is.na(oi_hatch[i])) {
        grid.pattern_hatch(sx, sy, type = oi_hatch[i],
                           colour = "black", spacing = 0.18, linewidth = 0.8)
    }
    popViewport()
}

popViewport()
popViewport()