| Library: | graphic |
| See also: | lab2rgb rgb2hls hls2rgb |
| Quantlet: | rgb2lab | |
| Description: | converts an RGB colour vector into an L*a*b* vector. |
| Usage: | Lab=rgb2lab(RGB) | |
| Input: | ||
| Lab | (n x 3) array of RGB colours assigned to n objects. The values of the R (red), G (green) and B (blue) channels range from 0 to 255. | |
| n/a | (n x 3) array of L*a*b* colours assigned to n objects. L* that ranges from 0 for black to 100 for white corresponds to luminance. L*, a* and b* are non-negative. Not all L*a*b colours can be represented as RGB ones. | |
library("xplore");
library("graphic");
R=255~0~0;
G=0~255~0;
B=0~0~255;
white=255~255~255;
black=0~0~0;
LabR=rgb2lab(R);
LabG=rgb2lab(G);
LabB=rgb2lab(B);
LabWhite=rgb2lab(white);
LabBlack=rgb2lab(black);
LabR;
LabG;
LabB;
LabWhite;
LabBlack;
LabNonRepr1=0~1~1; This colour cannot be represented as RGB
LabNonRepr2=100~1~1; This colour cannot be represented as RGB
RGBNonRepr1=lab2rgb(LabNonRepr1);
RGBNonRepr2=lab2rgb(LabNonRepr2);
RGBNonRepr1;
RGBNonRepr2;
L*, a* and b* values for red, green, blue, white and black and the RGB values for colours that are non-representable as RGB