image_alpha!

I = image_alpha!(img::GMTimage; alpha_ind::Integer, alpha_vec::Vector{Integer}, alpha_band::UInt8)

Change the alpha transparency of the GMTimage object img. If the image is indexed, one can either change just the color index that will be made transparent by using alpha_ind=n or provide a vector of transaparency values in the range [0 255]; This vector can be shorter than the orginal number of colors. Use alpha_band to change, or add, the alpha of true color images (RGB).

Examples

Change to the third color in cmap to represent the new transparent color

image_alpha!(img, alpha_ind=3)

Change to the first 6 colors in cmap by assigning them random values

image_alpha!(img, alpha_vec=round.(Int32,rand(6).*255))

See Also

image_cpt!, ind2rgb