DEFINITION MODULE GR_Conversions;

    (*
    **  Author : Peter Jardine
    **
    **  Version:
    **  1.0      17 Apr 92   New file - based on the work of 
    **                       Michael McCarthy & John Pfitzner,
    **                       CSP-960 Project, Semester 2, 1991.
    *)

PROCEDURE ConvertRGB2CMY(     red,  green,   blue   : REAL;
                          VAR cyan, magenta, yellow : REAL
                        );

PROCEDURE ConvertCMY2RGB(     cyan, magenta, yellow : REAL;
                          VAR red,  green,   blue   : REAL
                        );

PROCEDURE ConvertRGB2YIQ(     red, green, blue : REAL;
                          VAR Y,   I,     Q    : REAL
                        );

PROCEDURE ConvertYIQ2RGB(     Y,   I,     Q    : REAL;
                          VAR red, green, blue : REAL
                        );

PROCEDURE ConvertRGB2HSV(     red, green,      blue  : REAL;
                          VAR hue, saturation, value : REAL
                        );

PROCEDURE ConvertHSV2RGB(     hue, saturation, value : REAL;
                          VAR red, green,      blue  : REAL
                        );

PROCEDURE ConvertRGB2HLS(     red, green,     blue       : REAL;
                          VAR hue, lightness, saturation : REAL
                        );

PROCEDURE ConvertHLS2RGB(     hue, lightness, saturation : REAL;
                          VAR red, green,     blue       : REAL
                        );
    (*
    **  Colour coordinate conversion routines. Values of parameters
    **  red, green, blue, cyan, magenta, yellow, saturation, value,
    **  and lightness are define only in the range 0.0 to 1.0.  The
    **  value of hue is defined in the range from 0.0 to 360.0.
    *)

PROCEDURE ConvertNDC2DC(x, y : REAL; VAR col, row : INTEGER);
    (*
    **  Convert the NDC coordinates to physical (pixel) coordinates. This
    **  procedure takes account of the current aspect setting.
    *)

PROCEDURE ConvertDC2NDC(col, row : INTEGER; VAR x, y : REAL);
    (*
    **  Convert the physical (pixel) coordinates to NDC coordinates. This
    **  procedure takes account of the current aspect setting.
    *)

END GR_Conversions.