Sets the alpha channel in target where the given color occours in source,
* elsewhere alpha remains untouched. \n
* The color must have the same number of components of the source image. \n
* If target does not have an alpha channel, then its plane=0 is used. \n
* Supports all color spaces for source and all data types except complex.
* Images must have the same size.
*
* \verbatim im.ProcessSetAlphaColor(src_image: imImage, dst_image: imImage, src_color: table of numbers, dst_alpha: number) [in Lua 5] \endverbatim
* \ingroup colorproc
Sets the alpha channel in target where the given color occours in source, * elsewhere alpha remains untouched. \n * The color must have the same number of components of the source image. \n * If target does not have an alpha channel, then its plane=0 is used. \n * Supports all color spaces for source and all data types except complex. * Images must have the same size. * * \verbatim im.ProcessSetAlphaColor(src_image: imImage, dst_image: imImage, src_color: table of numbers, dst_alpha: number) [in Lua 5] \endverbatim * \ingroup colorproc