Rounding of value and chroma when using munsell2rgb

[pierreroudier]

At the moment, munsell2rgb requires the_value and the_chroma to be integers, otherwise a NA is returned:

> aqp::munsell2rgb(the_hue = '10YR', the_value = 3.9, the_chroma = 5.4)
[1] NA
> aqp::munsell2rgb(the_hue = '10YR', the_value = 3, the_chroma = 5 )
[1] "#614218FF"

I think this should be made clear(er) to users. Different options:

• Specifying it more explicitly in the documentation
• Get munsell2rgb to automatically convert the_value and the_chroma to integers, with a warning
• Get munsell2rgb to throw an error if the_value and/or the_chroma are not integers

[dylanbeaudette]

Correct. munsell2rgb is based only on conversion via lookup table.

All good points: the manual should make it more clear and offer a solution for non-standard Munsell notation, such as 8.9YR 3.9/5.4.

For example:

library(aqp)

# troublesome color, probably generated via conversion from other color space
m <- '8.9YR 3.69/5.4'

# parse into pieces, don't attempt conversion
(mp <- parseMunsell(m, convertColors = FALSE))

# conversion doesn't work because it is performed via LUT
aqp::munsell2rgb(mp$hue, mp$value, mp$chroma)

# you can find the closest Munsell "chip" in the LUT
getClosestMunsellChip(m, convertColors = FALSE)

# convert the closest "chip" into sRGB
getClosestMunsellChip(m, convertColors = TRUE, return_triplets=TRUE)

[dylanbeaudette]

Another idea, perhaps for aqp 2.0: make munsell2rgb more intelligent so as to invoke getClosestMunsellChip as needed.

Also, see #10 for the original issue on non-standard Munsell notation.

[pierreroudier]

Right,

I've whipped up a naive patch:

# If the_value or the_chroma are not integers, round them
  if ( !isTRUE(all.equal(the_value, as.integer(the_value) )) ) {
    the_value <- round(the_value)
    warning("'the_value' has been rounded to the nearest integer.")
  }
  if ( !isTRUE(all.equal(the_chroma, as.integer(the_chroma) )) ) {
    the_chroma <- round(the_chroma)
    warning("'the_chroma' has been rounded to the nearest integer.")
  }

See b1fdc73

But maybe invoking getMunsellMunsellChip would be better.

[dylanbeaudette]

This works for now. For next time:

1. finish Munsell color conversions #10 with full interpolation of non-standard Munsell notation in CIE LAB space
2. integrate into munsell2rgb as an option: round or interpolate to closest chip

[dylanbeaudette]

For some reason b1fdc73 didn't make it into the code. I've added a slightly modified version and related tests.