
vcluv(1)                     Khoros                      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 normal-
     ization 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 normal-
     ization 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.

Khoros                    Release: 1.0                          1

