image-access-pixels-to-bgra copies all the pixels in the Image Access object
into the vector
as a sequence of integer values in the range 0-255 for the blue, green, red and alpha components of each pixel. This function is optimized for the case where
has element type
(unsigned-byte 8). If the image has alpha, the values in
are assumed to be premultiplied.
image-access must be an Image Access object returned by make-image-access.
image-access-pixels-to-bgrato modify an image with alpha using colors that came from elsewhere, you need to premultiply them either by hand (multiply the color values by the alpha), or using color-to-premultiplied.
CAPI User Guide and Reference Manual (Windows version) - 3 Aug 2017