Gets the pixel values from an image.
image-access-transfer-from-image gets the pixel values from an image object, making them accessible via a corresponding Image Access object
image-access must be an Image Access object returned by make-image-access.
image-access-transfer-from-image transfers the pixel data from the window system into
, though it might do nothing on platforms where the window system allows direct access to the pixel data.
You can write the pixel data with
(setf image-access-pixel) and image-access-pixels-from-bgra.
CAPI User Guide and Reference Manual (Unix version) - 3 Aug 2017