externalize-image
gp
image
&key
maximum-colors
important-colors
&allow-other-keys
=>
external-image
The
externalize-image
function returns an external-image containing color information from
image
.
If
maximum-colors
is
nil
or if the screen has no palette, an external-image using all the colors in
image
is created.
If maximum-colors is an integer, the external-image containing image will be created using no more than that number of colors. If the image contains more than maximum-colors colors, the maximum-colors most frequently used colors will be accurately stored; the remainder will be approximated by nearest colors out of the accurate ones, using internal Color System parameters as the weighting factors for the color distance.
The value of important-color is recorded in the external-image for later use, and specifies the number of colors required to draw a good likeness of the image. The default value is the number of colors in the image.