vcluv(1)

PROGRAM
vcluv - Conversion from a linear Color Space to the Luv color space.

SYNTAX

vcluv

-i  input image filename

-o  output image filename

[-n]
    normalization factor

[-V]
    Gives the version for vcluv

[-U]
    Gives the usage for vcluv

[-P]
    Prompts for command line options

[-A [file1]]
    Creates the answer file called vcluv.ans or file1

[-a [file1]]
    Uses vcluv.ans or file1 as the answer file

DESCRIPTION
vcluv converts ntsc RGB,generic RGB ntsc YIQ, ntsc CMY, cie XYZ, cie UVW or GENERIC color spaces to cieucs Luv color spaces. Color images are displayed and manipulated using the NTSC receiver primary color system; thus reference white is set to R = 1, B = 1, G = 1.

The algorithm used is as follows:
L = 25(Y/Y0)^1/3 - 16
u = 13L(u' - u0')
u = 13L(v' - v0')
where u', v', u0' and v0' are
u' = 4X / X + 15Y + 3Z
v' = 9Y / X + 15Y + 3Z
u0' = 4X0 / X + 15Y + 3Z
u0' = 9Y0 / X + 15Y + 3Z

X0, Y0 and Z0 are calculated by setting R = 1, G = 1, B = 1 and converting to the XYZ color space (see vcltrans).

This routine needs to work with an image normalized between 0 and 1.

This algorithm was taken from Fundamentals of Digital Image Processing, Jain, and Color Science: Concepts and Methods, Quantitative Data and Formulae, Wyszecki and Stiles.

The -n option specifies the normalization factor. The default value is 255.

This routine will not touch the data map; therefore, the map may be invalid after running this routine. The map may be deleted from the image or a new map may be inserted.

The -n option (normalization) defaults to 255.0.

REQUIRED ARGUMENTS

-i  type: infile
    desc: input image filename

-o  type: outfile
    desc: output image filename

OPTIONAL ARGUMENTS

-n  type: float
    desc: normalization factor
    default: 255
    bounds: value > 0.0

EXAMPLES
vcluv -i image1 -o image2
this will convert image1 (RGB) to image2 (Luv) using normalization factor = 255. Normalization factor = 255 is used because an 8 color plane machine (256 colors) is being used.

vcrgbhls -i image1 -o image2 -n 15
this will convert image1 (XYZ) to image2 (Luv) using normalization factor = 15. Normalization factor = 15 is used because a 4 color plane machine (16 colors) is being used.

SEE ALSO
intro(1), verror(3), vgparms(3), vutils(3), lvcluv(3)

RESTRICTIONS
vcluv must have an input image of data storage type FLOAT and the input image color map model must be of type ntscRGB, genericRGB, cieXYZ, cieUVW, ntscYIQ, ntscCMY, or GENERIC.

COPYRIGHT
Copyright 1991, University of New Mexico. All rights reserved.