[Cyan]<PreISLCedar>Imager>ConstantColors.mesa!1

ConstantColors.mesa

Michael Plass, August 1, 1983 11:19 am

Last Edited by: Stone, February 10, 1984 4:47:16 pm PST

Last Edited by: Pier, January 19, 1984 2:21 pm

DIRECTORY

ImagerBasic USING [ConstantColor],

ColorModels USING [undefined, Calibration],

Rope USING [ROPE];

ConstantColors: CEDAR DEFINITIONS = BEGIN

black: ConstantColor;

white: ConstantColor;

-- All REAL values below should be in the range [0..1] except for undefined hues.

-- HSV is hue, saturation, value (hexacone model);

-- HSL is hue, saturation, lightness (double ended hexacone)

-- RGB is red, green, blue.

Defaulting the calibration assumes an "ideal" monitor device

undefined: REAL = ColorModels.undefined; -- (-1.0)

Calibration: TYPE = ColorModels.Calibration;

ConstantColor: TYPE = ImagerBasic.ConstantColor;

UndefinedColor: SIGNAL;

IntensityToColor: PROC [intensity: REAL, cal: Calibration ← NIL] RETURNS [ConstantColor];

HSVToColor: PROC [h, s, v: REAL, cal: Calibration ← NIL] RETURNS [ConstantColor];

HSLToColor: PROC [h, s, l: REAL, cal: Calibration ← NIL] RETURNS [ConstantColor];

RGBToColor: PROC [r, g, b: REAL, cal: Calibration ← NIL] RETURNS [ConstantColor];

-- The above 4 procedures will SIGNAL Runtime.BoundsFault for any argument

-- not in [0..1]; resuming the signal will perform arg ← MAX[0,MIN[1,arg]].

CIEToColor: PROC [x,y,Y: REAL] RETURNS [ConstantColor];

--CIE color system

NameToColor: PROC [name: Rope.ROPE, cal: Calibration ← NIL] RETURNS [ConstantColor];

--Color naming system.

The hope is that this will be a set of "intuitive" descriptive names that people could type or select. A color name is composed of three properties, usually presented in order: lightness, saturation, hue. The current set of names for these properties is:

Lightness is one of: very dark, dark, medium, light, very light (default is medium)

Saturation is one of: weak, moderate, strong, vivid (default is vivid)

Hue is one of: red, orange, yellow, green, blue, purple, brown

You may also interpolate between the hue names as follows: red, orangish-red, red-orange, reddish-orange, orange... You may only interpolate between adjacent hues as defined in the list. Brown is actually a special case of orange, so you can interpolate from red to brown, and from brown to yellow.

There are three more hue names for achromatic colors: black, white and gray (grey).

Black and white are complete descriptions by themselves. Gray may have a valid lighness parameter (default is medium).

The following routines are inversion routines for the procedures above.

Note that for achromatic colors the hue parameters will be undefined.

ColorToIntensity: PROC[color: ConstantColor, cal: Calibration ← NIL] RETURNS[intensity: REAL];

ColorToHSV: PROC [color: ConstantColor, cal: Calibration ← NIL] RETURNS [h, s, v: REAL];

ColorToHSL: PROC [color: ConstantColor, cal: Calibration ← NIL] RETURNS [h, s, l: REAL];

ColorToRGB: PROC [color: ConstantColor, cal: Calibration ← NIL] RETURNS [r, g, b: REAL];

ColorToCIE: PROC [color: ConstantColor] RETURNS [x,y,Y: REAL];

ColorToName: PROC [color: ConstantColor, cal: Calibration ← NIL] RETURNS [name: Rope.ROPE];

END.