Used in cvd_emulator. Takes an image object and converts
the colors using deutan, protan,
tritan, desaturate functions. The image
will be written to disc as a PNG file.
cvd_image(img, type, file, severity = 1)array as returned by readPNG and readJPEG
of size height x width x depth. The depth coordinate contains
R/G/B and alpha if given (png).
string name of the function which will be used to
convert the colors (deutan, protan, tritan, desaturate).
If set to original the image will be written as is.
string with (full) path to resulting image. Has to
be a png image name.
numeric. Severity of the color vision defect, a number between 0 and 1.