lab2double - Convert L*a*b* data to double

Syntax

labd = lab2double(lab)

Description

labd = lab2double(lab) converts an M-by-3 or M-by-N-by-3 array of L*a*b* color values to class double. The output array labd has the same size as lab.

The Image Processing Toolbox software follows the convention that double-precision L*a*b* arrays contain 1976 CIE L*a*b* values. L*a*b* arrays that are uint8 or uint16 follow the convention in the ICC profile specification (ICC.1:2001-4, www.color.org) for representing L*a*b* values as unsigned 8-bit or 16-bit integers. The ICC encoding convention is illustrated by these tables.

Value (L*)	uint8 Value	uint16 Value
0.0	0	0
100.0	255	65280
100.0 + (25500/65280)	None	65535

Value (a* or b*)	uint8 Value	uint16 Value
-128.0	0	0
0.0	128	32768
127.0	255	65280
127.0 + (255/256)	None	65535

Class Support

lab is a uint8, uint16, or double array that must be real and nonsparse. labd is double.

Examples

Convert full intensity neutral color (white) from uint8 to double.

lab2double(uint8([255 128 128]))
ans =

   100     0     0

See Also

applycform | lab2uint16 | lab2uint8 | makecform | whitepoint | xyz2double | xyz2uint16

How To

• Color Space Conversions

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