Returns an external image containing color information from an image.
graphics-ports
externalize-image gp image &key maximum-colors important-colors type quality &allow-other-keys => external-image
gp⇩ |
A CAPI pane. |
image⇩ |
An image. |
maximum-colors⇩ |
An integer or nil . The default is nil . |
important-colors⇩ |
An integer or nil . |
type⇩ |
One of the keywords :bmp , :jpg , :jpeg , :png and :tiff . Other keywords may be supported, depending on the platform. |
quality⇩ |
An integer in the range [0,100]. |
external-image⇩ |
An external image. |
The function externalize-image
returns an external-image containing color information from image, which should be an image that can be drawn to gp.
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, then 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.
important-colors is recorded in 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.
If type is supplied, it must be a keyword which specifies a known type, as returned by list-known-image-formats with for-writing-too t
. The types :bmp
, :jpg
, :png
and :tiff
are known on all platforms (except Motif). Additionally, :jpeg
is an as alias for :jpg
.
quality is used for writing a JPG image on GTK+. It must be an integer in the inclusive range [0,100]. High values generate better images and larger files.
make-image-from-port
write-external-image
13 Drawing - Graphics Ports
CAPI User Guide and Reference Manual (Unix version) - 01 Dec 2021 19:33:02