colorspace

Color space conversion of image

out = colorspace(s, im) converts the image im to a different color space according to the string s which specifies the source and destination color spaces, s = 'dest<-src', or alternatively, s = 'src->dest'. Input and output images have 3 planes.

[o1,o2,o3] = colorspace(s, im) as above but specifies separate output channels or planes.

colorspace(s, i1,i2,i3) as above but specifies separate input channels.

Supported color spaces are:

'RGB'	R'G'B' Red Green Blue (ITU-R BT.709 gamma-corrected)
'YPbPr'	Luma (ITU-R BT.601) + Chroma
'YCbCr'/'YCC'	Luma + Chroma ("digitized" version of Y'PbPr)
'YUV'	NTSC PAL Y'UV Luma + Chroma
'YIQ'	NTSC Y'IQ Luma + Chroma
'YDbDr'	SECAM Y'DbDr Luma + Chroma
'JPEGYCbCr'	JPEG-Y'CbCr Luma + Chroma
'HSV'/'HSB'	Hue Saturation Value/Brightness
'HSL'/'HLS'/'HSI'	Hue Saturation Luminance/Intensity
'XYZ'	CIE XYZ
'Lab'	CIE Lab* (CIELAB)
'Luv'	CIE Luv* (CIELUV)
'Lch'	CIE L*ch (CIELCH)

Notes

RGB input is assumed to be gamma encoded
RGB output is gamma encoded
All conversions assume 2 degree observer and D65 illuminant.
Color space names are case insensitive.
When R'G'B' is the source or destination, it can be omitted. For example 'yuv<-' is short for 'yuv<-rgb'.
MATLAB uses two standard data formats for R'G'B': double data with intensities in the range 0 to 1, and uint8 data with integer-valued intensities from 0 to 255. As MATLAB's native datatype, double data is the natural choice, and the R'G'B' format used by colorspace. However, for memory and computational performance, some functions also operate with uint8 R'G'B'. Given uint8 R'G'B' color data, colorspace will first cast it to double R'G'B' before processing.
If IM is an Mx3 array, like a colormap, OUT will also have size Mx3.

Author

Pascal Getreuer 2005-2006