Color-Pixel-Image

Color images are represented by color-pixel-image objects which have three pixel-image objects to represent red, green, and blue components in RGB representation, or hue, lightness, and saturation components in the HLS model. Conversion between RGB and HLS is supported.

color-pixel-image [class]

  :super   propertied-object 

  :slots 		 width height component1 component2 component3 

represents color images with three pixel-image objects.

:width [method]

returns the width of this image.

:height [method]

returns the height of this image.

:size [method]

returns $width \times height$ of this image.

:red [method]

returns component1.

:green [method]

returns component2.

:blue [method]

returns component3.

:hue [method]

returns component1. A hue value between 0 and 360 is represented by a byte value between 0 and 255.

:lightness [method]

returns component2. The normalized brightness values (0..1) are mapped into integers between 0 and 255.

:saturation [method]

returns component3. The normalized saturation values (0..1) are mapped into integers between 0 and 255.

:pixel x y [method]

returns a list of three integers each of which is taken from component1, component2 and component3 at (x,y). This triplet can be interpreted either as RGB values or HLS values.

:monochromize &optional (NTSC nil) [method]

computes brightness from RGB components and returns a new pixel-image. If NTSC is nil, $(R+G+B)/3$ is computed. If T, $0.299*R+0.587*G+0.114*B$ is computed.

:HLS [method]

assuming this image is representing an RGB image, converts the image into HLS representation. RGB2HLS is called for the conversion of each pixel.

:RGB [method]

assuming this image is representing an HLS image, converts the image into RGB representation. HLS2RGB is called for the conversion of each pixel.

:halve [method]

returns color-pixel-image that is shrunk into half-size image.

:display &optional (win *color-viewer*) [method]

displays this color-pixel-image in a xwindow designated by win by using :putimage. Each pixel value is referred as a index in x's color map. To get a desired appearance, this pixel-image must have been translated by proper LUTs.

:display-lut &optional (newlut1) (newlut2 newlut1) (newlut3 newlut2) [method]

sets look-up tables newlut1, newlut1 and newlut1 as display-lut, respectively. Then translates this image using this look-up table and sets translated pixel-image object as xpicture.

detects edge of this image. And displays this edge on this image.

:hex &optional (x 0) (y 0) (w 16) (h 16) (strm t) [method]

prints pixel data in the specified rectangular region in the hexadecimal format.

:hex1 &optional (x 0) (y 0) (w 64) (h 16) (strm t) [method]

prints pixel data in the specified rectangular region in the hexadecimal format.

:prin1 strm &rest msg [method]

prints this image-pixel object with its name and dimensions.

:init width height &optional r g b [method]

defines the size of a color image and allocates pixel-images for each color component.

Provided a ppm file, you can extract color (hue) values out of the image and display it in an xwindow by the following program.

(setq ppmimg (read-pnm "xxx.ppm"))
(send ppmimg :hls)   ; RGB to HLS conversion
(make-ximage (send ppmimg :hue) *rainbow32*)