NEWS in package ‘colorspace’

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Changes in version 2.0-3

• Added the advanced perceptual contrast algorithm (APCA) that is under development for the next major revision of the WCAG as an alternative algorithm in contrast_ratio(). See https://github.com/Myndex/SAPC-APCA.

• Fixed a bug in lighten() and darken() for the case when some colors were named (e.g., "blue") rather than hex strings only. In that case linear RGB rather than sRGB was incorrectly used internally (reported by Colin Goodall).

Changes in version 2.0-2

• New function contrast_ratio() for computing and visualizing contrast ratios of pairs of colors as defined in the Web Content Accessibility Guidelines (WCAG) (https://www.w3.org/TR/WCAG21/) of the World Wide Web Consortium (W3C).

Changes in version 2.0-1

• Added two new palettes from the viridis family (viridis/viridisLite), namely "Rocket" and "Mako" in sequential_hcl().

• Assure that all do.call() for the ggplot2 scale functions are made with envir = parent.frame() in order to avoid problems with non-standard evaluation, as reported in: https://stackoverflow.com/questions/66049336/paste-name-in-scale-fill-color-in-colorspace-does-not-work-in-a-loop

• New function extract_transparency() for extracting alpha transparency from color specifications, either as numeric, integer, character or hexmode vectors. This accompanies the previously available function adjust_transparency() allowing for more flexible modifications of alpha transparencies in colors.

Changes in version 2.0-0

• Release of version 2.0-0 accompanying the publication of the paper "colorspace: A Toolbox for Manipulating and Assessing Colors and Palettes" in the Journal of Statistcal Software at https://doi.org/10.18637/jss.v096.i01. The paper is a compact version of the package web page (https://colorspace.R-Forge.R-project.org/) including some more discussion of related methods and software along with some more references to the scientific literature.

• New function adjust_transparency() that adjusts the alpha transparency of some color specification and returns a hexadecimal string where the alpha component is modified, added, or removed.

• Added three more palettes from Fabio Crameri's scientific color maps (scico), namely "Hawaii" and "Batlow" in sequential_hcl() and "Roma" in divergingx_hcl().

• Additional option cvd in swatchplot() so that color vision deficiency emulation can be included on the fly.

• Added binned ggplot2 color scales (in addition to discrete and continuous).

• Changed the default colors in specplot() from rainbow_hcl(3) to qualitative_hcl(3) which is darker and has more chroma. Also, the order of the legend has been reversed (Luminance / Chroma / Hue) so that the legend labels are closer to the axis that they pertain to.

• Improve the documentation of the LUV() and LAB() color spaces, pointing out that the U/V and A/B coordinates are typically in [-100, 100] but can actually be exceeded by highly saturated colors.

• Bug fix in diverging_hcl() and divergingx_hcl() where the central color of the diverging palette could sometimes collapse to transparent white due to numerical inaccuracies on 32-bit platforms.

• Improve the documentation of the HSV() and HLS() color spaces. These do NOT necessarily correspond to sRGB; we can convert from these to any RGB space that we choose (linear or non-linear, any whitepoint). In particular, if we want to convert from one of these color spaces to XYZ or beyond, we must first convert to a specific RGB color space.

Changes in version 1.4-1

• New article/vignette "Somewhere over the Rainbow" with published examples of RGB rainbow palettes (or similar highly saturated and non-monotonic palettes).

• Bug fix in divergingx_hcl(n) with even n where the two central colors were erroneously duplicated. Also, partial matching of palette names has been fixed.

• New sequential multi-hue palette: Purple-Yellow. This is a slightly improved version (i.e., with higher luminance contrast) of the palette used in Figure 4 of Stauffer et al. (2015, BAMS).

• New flexible diverging palette Zissou 1 in divergingx_hcl(). This closely matches the palette of the same name in wesanderson. Note that this is rather unbalanced, has relatively low luminance contrasts and uses very high chroma throughout.

• New palette Cividis in divergingx_hcl() approximating the palette of the same name from the viridis family. While luminance increases monotonically from dark to light in the palette (thus indicating a sequential and not a diverging palette), the hue and chroma trajectories resemble a diverging pattern. Therefore, the flexibility of divergingx_hcl() is needed and the palette could not be approximated by sequential_hcl().

• Limits of hue axis are improved in specplot(). Previously, the hues were always matched to [0, 100] on the chroma/luminance axis. Now they are matched to [0, maximum chroma].

Changes in version 1.4-0

• Major update of the package that enhances many of its capabilities, e.g., more refined palettes, named palettes, ggplot2 color scales, visualizations for assessing palettes, more and enhanced shiny and Tcl/Tk apps, color vision deficiency emulation, and much more. See below for further details. A new web site presenting and documenting the package has been launched at https://colorspace.R-Forge.R-project.org/

• Claus O. Wilke and Claire D. McWhite joined the colorspace team, adding and enhancing various features, including (but not limited to) especially the color vision deficiency emulation, the ggplot2 palettes, and new shiny apps.

• New function simulate_cvd() for simulating color vision deficiencies with convenience interfaces deutan(), protan(), and tritan().

• New function hcl_palettes() to query pre-defined HCL-based palettes: qualitative, sequential (single-hue), sequential (multi-hue), diverging. The corresponding print(), plot(), and summary() methods can help to explore the palettes.

• Pre-defined HCL palettes are taken from previous publications about colorspace as well as approximations from other packages (ColorBrewer.org, CARTO, viridis, scico).

• Users can also register their own custom color palettes for subsequent usage (within the same session) in qualitative_hcl(), sequential_hcl(), and diverging_hcl() using the register = "..." argument. To generally make such custom palettes available, a registration R code a la colorspace::qualitative_hcl(..., register = "myname") can be placed in the .Rprofile or similar startup scripts. Also the choose_color()/hclwizard() app allows to register palettes in the current session.

• New and more flexible qualitative_hcl() palette function. This is similar to the old rainbow_hcl() but allows to use the pre-defined palettes and change the parameters more easily.

• Palette function sequential_hcl() is now substantially more flexible: encompasses both single-hue and multi-hue palettes; gained a new parameter cmax for non-monotonic chroma paths. Parameters h1, h2, c1, c2, l1, l2, p1, p2, cmax allow to easily modify existing palettes in just a few HCL parameters.

• Function diverging_hcl() is introduced as a copy of diverge_hcl() for a more consistent naming of the *_hcl palettes where * is one of the adjectives "qualitative", "sequential", and "diverging". Both diverging_hcl() and diverge_hcl() now also gained a cmax argument just like sequential_hcl(). Individual parameters h1, h2, c1, l1, l2, p1, p2 can also be easily modified.

• New functions divergingx_hcl()/divergex_hcl() have been added for fully fle_x_ible diverging palettes (as opposed to the more restricted balanced palettes in diverging_hcl()/diverge_hcl()). These support parameters h1, h2, h3, c1, c2, c3, l1, l2, l3, p1, p2, p3, p4, cmax1, cmax2.

• Many new predefined palettes that facilitate close approximation of almost all palettes from ColorBrewer.org/RColorBrewer, CARTO/rcartocolor, and viridis. Additionally, approximations to a few of Fabio Crameri's scientific color maps (scico) are available as well.

• New interactive shiny app hcl_color_picker() - or equivalently, choose_color() - for exploring HCL colors, and manually assembling individual colors or palettes. Douglas C. Wu (@wckdouglas) provided the original implementation for the color palette feature.

• New functions lighten() and darken() for programatically lightening and darkening colors.

• New convenience function swatchplot() that facilitates displaying color swatches to display and compare collections of color palettes.

• specplot() gained an argument y=NULL to optionally display a second palette and compare their trajectories. By default, specplot() now only shows the HCL spectrum but not the RGB spectrum (rgb = FALSE) because it is mainly used for illustrating and comparing properties of HCL-based palettes.

• New function hclplot() for visualizing trajectories of color palettes in two-dimensional HCL space projections.

• New function demoplot() that makes the demonstration plots (map, heatmap, pie, lines, etc.) from the choose_palette()/hclwizard() app available outside the GUI on the command line.

• Added a new function max_chroma() that (approximately) computes the maximum chroma possible for a given hue and luminance combination in HCL space.

• Registration of C routines.

• In LAB_to_XYZ conversion, replace decimal approximations with exact rational numbers (reported by Glenn Davis). Follows Bruce Lindbloom: http://brucelindbloom.com/index.html?LContinuity.html

• New function whitepoint() that can both query the current whitepoint and set it to a different value. By default CIE D65 with XYZ coordinates 95.047, 100.000, 108.883 is used. But it is possible to set another global whitepoint now, used for all conversions in the package (suggested by Glenn Davis).

• Fixed a bug in desaturate() for named colors (such as "gray92") where erroneously the RGB() rather than sRGB() model was used internally.

• Added argument desaturate(..., amount = 1) for optional partial desaturation.

Changes in version 1.3-2

• Fixed error in as_HLS(), which was passing ans rather than color as the colour to convert (and that was producing not only wrong results, but random results because the values in ans were not initialized). Thanks to Thomas Julou for the report.

Changes in version 1.3-1

• Fixed erroneous use of return rather than return() in choose_palette()/hclwizard().

Changes in version 1.3-0

• In addition to the Tcl/Tk-based GUI for choose_palette() there is now a shiny-based GUI. choose_palette() by default still uses the Tcl/Tk version while hclwizard() is a new wrapper that by default calls the new shiny version.

• New function specplot() that converts a given palette in hex codes to RGB and HCL coordinates and visualizes their spectrum as a line plot.

• hex2RGB() now omits the alpha channel (if any) in the hex colors provided.

Changes in version 1.2-7

• Extended choose_palette() for sequential palettes with multiple hues: Now two palettes are included in the examples that are very close to "viridis" and "magma" from matplotlib in Python (also available in R via package viridis)

• Changed Depends/Imports/Suggests to conform with current R CMD check.

Changes in version 1.2-6

• Moved tcltk again from Imports to Suggests to facilitate usage of colorspace on platforms where tcltk is not available.

Changes in version 1.2-5

• Changed Depends/Imports/Suggests to conform with current R CMD check.

Changes in version 1.2-4

• Bug fix for choose_palette() when using palette functions with optional alpha channels.

Changes in version 1.2-3

• Alpha channel is preserved in desaturate for named colors (especially "transparent" and NA). (Reported by Simon Potter.)

• Added alpha argument for all palette functions (see ?rainbow_hcl).

• Small fixups for R CMD check.

Changes in version 1.2-2

• Names of colors are preserved in hex() and hex2RGB() now. (Reported by Richard Cotton.)

Changes in version 1.2-1

• If a new version of the dichromat package (> 1.2-4) with tritan support is found, this is interfaced in choose_palette().

Changes in version 1.2-0

• New Tcl/Tk-based GUI for choosing different types of palettes: qualitative (rainbow_hcl), single-hue sequential (sequential_hcl), multi-hue sequential (heat_hcl), and diverging (diverge_hcl). The GUI provides a wide collection of pre-stored palettes, easy manipulation of the corresponding arguments, illustration through a broad range of plot types (maps, heatmaps, variations of bar plots, scatter plots, and many more), emulation of desaturation and dichromatic vision, loading/saving palettes, etc.

• Bug fix in polarLAB_to_LAB conversion.

• All .Call() calls now with PACKAGE = "colorspace".

• Added some simple tests based on the examples and vignette.

Changes in version 1.1-1

• Added desaturate() function for removal of chroma in a given vector of colors.

• Bug fix in HLS_to_RGB conversion for s == 0.

Changes in version 1.1-0

• Added sRGB colorspace. (Existing RGB colorspace is linearized "sRGB".)

• Conversions to and from HSV and HSL can only occur from or to RGB or sRGB (because both HSV and HSL are relative colorspaces, meaning relative to a particular RGB colorspace). (Converting to or from RGB gives a different result compared to conversion to or from sRGB.)

• All gamma parameters in all R-level functions have been deprecated. (The sRGB colorspace has implicit gamma.)

Changes in version 1.0-1

• "Escaping RGBland" paper is now published Computational Statistics & Data Analysis as doi:10.1016/j.csda.2008.11.033. Citation and references updated accordingly.

Changes in version 1.0-0

• New version to accompany the "Escaping RGBland" paper accepted for publication in Computational Statistics & Data Analysis, see citation("colorspace")

Changes in version 0.97

• Moved color palettes from vcd to colorspace, including vignette("hcl-colors")

• Added infrastructure for HLS color space

• New CITATION file