image_keep_color

an image read into R 
by <code>magick::image_read</code>.

the same 
as <code>magick::image_transparent</code>.
You can use 1 or more colors.

color

the same 
as <code>magick::image_transparent</code>. 
However, Its length must either be 1 or the same 
as <code>color</code>.

fuzz

if it is "magick" (default), the result is 
a magick image, if it is "raster", the result is a matrix.

result

This function keeps pixels with certain 
colors unchanged and transforms 
others into grayscale.
The function is in fact a wrapper of 
<code>magick::image_transparent</code>, so it 
uses the latter's <code>color</code> and <code>fuzz</code>
parameters. NOTE: the function only works 
for fully opaque or fully 
transparent (labelled as "transparent") pixels.

An extension to 'ggplot2' and 'magick'. It contains
three groups of functions: Functions in the first group draw 'ggplot2' - based plots: geom_shading_bar() draws barplot
with shading colors in each bar. geom_rect_cm(), geom_circle_cm() and geom_ellipse_cm() draw rectangles, circles
and ellipses with centimeter as their unit. Thus their sizes do not change when the coordinate system or the aspect ratio
changes. annotation_transparent_text() draws labels with transparent texts. annotation_shading_polygon() draws irregular
polygons with shading colors. Functions in the second group generate coordinates for regular shapes and make linear transformations. Functions in the third group are 'magick' - based functions facilitating image processing.

image_keep_color: Keep Some Colors Unchanged and Make Others into Grayscale

Description

Usage

Arguments