[原创]：数字值、RGB值和HSL值的颜色转换函数

highflybird

这几天研究了一下CAD 中的颜色。
CAD中自从有了真彩色值后，图元表的对颜色的描述就不仅仅是62的关联表了，多了一个420的关联表。
现在我把420关联的数字表，RGB值和HSL值得转换函数列在下面。

数字值转RGB值函数
(Number->RGB 12233333)  返回值  (186 170 117)
RGB值转数字值函数
(RGB->Number 186 170 117) 返回值 12233333
RGB值转HSL值函数
(rgb->hsl 230 120 24)  返回值 (27 81 49)
HSL值转RGB值函数
(hsl->rgb 260 34 49) 返回值 (110 82 167)

[php]
;;;参数列表R红色值(0-255),G绿色值(0-255),B蓝色值(0-255),超出范围则不正确。
;;;参数列表C0为颜色值，整数，最大范围256*256*256,超出范围则不正确。
;;;===============
;;;把truecolordlg
;;;420构成的数值返
;;;回RGB列表.     
;;;===============
(defun Number->RGB (C0 / R0 G0 B0)
  (setq B0 (rem C0 256))
  (setq G0 (rem (/ (- C0 B0) 256) 256))
  (setq R0 (rem (/ (- C0 B0 (* G0 256)) (* 65536)) 256))
  (list R0 G0 B0)
)
;;;===============
;;;把truecolordlg
;;;420构成的数值返
;;;回RGB列表.     
;;;===============
(defun RGB->Number (R0 G0 B0)
  (+ B0 (* G0 256) (* R0 65536))
)
[/php]
;;;参数列表为HSL列表H (0-360),S (0-100),L (0-100),超出范围则不正确。
;;;返回值列表R红色值(0-255),G绿色值(0-255),B蓝色值(0-255)
[php]
;;;===============
;;;HSL转RGB      
;;;返回RGB值的列表
;;;===============
(defun Hsl->rgb (Hue Saturation Light / h s l r g b var2 var1)
  (setq h (/ Hue 360.0)
        s (/ Saturation 100.0)
        l (/ Light 100.0)
  )
  (if (= s 0)
    (setq r (* l 255)
          g (* l 255)
          b (* l 255)
    )
    (setq var2 (if (< l 0.5)(* l (1+ s))(+ l s (* s l -1)))
          var1 (- (* 2 l) var2)
          r (* 255 (Hue->RGB var1 var2 (+ h 0.33333333)))
          g (* 255 (Hue->RGB var1 var2 h))
          b (* 255 (Hue->RGB var1 var2 (- h 0.33333333)))
    )
  )
  (list (fix r) (fix g) (fix b))
)
;;;Hue转RGB
(defun Hue->rgb (v1 v2 vHue / vH)
  (cond
    ((< vHue 0) (setq vH (1+ vHue)))
    ((> vHue 1) (setq vH (1- vHue)))
    (t (setq vH vHue))
  )
  (cond
    ((< (* 6 vH) 1) (+ v1 (* (- v2 v1) 6 vH)))
    ((< (* 2 vH) 1) v2)
    ((< (* 3 vH) 2) (+ v1 (* (- v2 v1) 6 (- 0.66666667 vH))))
    (t v1)
  )
)

[/php]
参数列表R 红色值(0-255) ,G绿色值(0-255),B蓝色值(0-255),超出范围则不正确。
返回值为HSL列表H (0-360) S (0-100) L (0-100),
[php]
;;;===============
;;;RGB转HSL      
;;;返回HSL值的列表
;;;===============
(defun RGB->HSL(R G B / var_R var_G var_B var_min var_max
                        del_max del_R del_G del_B H L S)
  (setq var_R (/ R 255.0))
  (setq var_G (/ G 255.0))
  (setq var_B (/ B 255.0))
  (setq var_min (min var_R var_G var_B))
  (setq var_max (max var_R var_G var_B))
  (setq del_max (- var_max var_min))
  (setq L (/ (+ var_max var_min) 2))
  (if (= del_max 0)
    (setq H 0 S 0)
    (progn
      (setq S (if (< L 0.5)
                (/ del_max (+ var_max var_min))
                (/ del_max (- 2 var_max var_min))
              )
            del_R (/ (+ (/ (- var_max var_R) 6)  (/ del_Max 2 )) del_max)
            del_G (/ (+ (/ (- var_max var_G) 6)  (/ del_Max 2 )) del_max)
            del_B (/ (+ (/ (- var_max var_B) 6)  (/ del_Max 2 )) del_max)
      )
      (cond
        ( (= var_R var_max)
          (setq H (- del_B del_G))
        )
        ( (= var_G var_max)
          (setq H (+ (/ 1.0 3) del_R (- del_B)))
        )
        ( (= var_B var_max)
          (setq H (+ (/ 2.0 3) del_G (- del_R)))
        )
      )
      (cond
        ( (< H 0) (setq  H (1+ H)))
        ( (> H 1) (setq  H (1- H)))
      )
    )
  )
  (setq h (* 360 H)
        S (* 100 S)
        l (* 100 l)
  )
  (list (fix H) (fix S) (fix L))
)
[/php]

aeo

sample\color-util.lsp

WHGF

下面是我收集的色彩转换方法，没有整理，需要的朋友可以参考

RGB —> HSL
var_R = ( R / 255 ) //RGB values = From 0 to 255
var_G = ( G / 255 )
var_B = ( B / 255 )

var_Min = min( var_R, var_G, var_B ) //Min. value of RGB
var_Max = max( var_R, var_G, var_B ) //Max. value of RGB
del_Max = var_Max - var_Min //Delta RGB value

L = ( var_Max + var_Min ) / 2

if ( del_Max == 0 ) //This is a gray, no chroma...
{
H = 0 //HSL results = From 0 to 1
S = 0
}
else //Chromatic data...
{
if ( L < 0.5 ) S = del_Max / ( var_Max + var_Min )
else S = del_Max / ( 2 - var_Max - var_Min )

del_R = ( ( ( var_Max - var_R ) / 6 ) + ( del_Max / 2 ) ) / del_Max
del_G = ( ( ( var_Max - var_G ) / 6 ) + ( del_Max / 2 ) ) / del_Max
del_B = ( ( ( var_Max - var_B ) / 6 ) + ( del_Max / 2 ) ) / del_Max

if ( var_R == var_Max ) H = del_B - del_G
else if ( var_G == var_Max ) H = ( 1 / 3 ) + del_R - del_B
else if ( var_B == var_Max ) H = ( 2 / 3 ) + del_G - del_R

if ( H < 0 ) ; H += 1
if ( H > 1 ) ; H -= 1
}
HSL —> RGB
if ( S == 0 ) //HSL values = From 0 to 1
{
R = L * 255 //RGB results = From 0 to 255
G = L * 255
B = L * 255
}
else
{
if ( L < 0.5 ) var_2 = L * ( 1 + S )
else var_2 = ( L + S ) - ( S * L )

var_1 = 2 * L - var_2

R = 255 * Hue_2_RGB( var_1, var_2, H + ( 1 / 3 ) )
G = 255 * Hue_2_RGB( var_1, var_2, H )
B = 255 * Hue_2_RGB( var_1, var_2, H - ( 1 / 3 ) )
}


--------------------------------------------------------------------------------

Hue_2_RGB( v1, v2, vH ) //Function Hue_2_RGB
{
if ( vH < 0 ) vH += 1
if ( vH > 1 ) vH -= 1
if ( ( 6 * vH ) < 1 ) return ( v1 + ( v2 - v1 ) * 6 * vH )
if ( ( 2 * vH ) < 1 ) return ( v2 )
if ( ( 3 * vH ) < 2 ) return ( v1 + ( v2 - v1 ) * ( ( 2 / 3 ) - vH ) * 6 )
return ( v1 )
}
RGB —> HSV
var_R = ( R / 255 ) //RGB values = From 0 to 255
var_G = ( G / 255 )
var_B = ( B / 255 )

var_Min = min( var_R, var_G, var_B ) //Min. value of RGB
var_Max = max( var_R, var_G, var_B ) //Max. value of RGB
del_Max = var_Max - var_Min //Delta RGB value

V = var_Max

if ( del_Max == 0 ) //This is a gray, no chroma...
{
H = 0 //HSV results = From 0 to 1
S = 0
}
else //Chromatic data...
{
S = del_Max / var_Max

del_R = ( ( ( var_Max - var_R ) / 6 ) + ( del_Max / 2 ) ) / del_Max
del_G = ( ( ( var_Max - var_G ) / 6 ) + ( del_Max / 2 ) ) / del_Max
del_B = ( ( ( var_Max - var_B ) / 6 ) + ( del_Max / 2 ) ) / del_Max

if ( var_R == var_Max ) H = del_B - del_G
else if ( var_G == var_Max ) H = ( 1 / 3 ) + del_R - del_B
else if ( var_B == var_Max ) H = ( 2 / 3 ) + del_G - del_R

if ( H < 0 ) ; H += 1
if ( H > 1 ) ; H -= 1
}
HSV —> RGB
if ( S == 0 ) //HSV values = From 0 to 1
{
R = V * 255 //RGB results = From 0 to 255
G = V * 255
B = V * 255
}
else
{
var_h = H * 6
var_i = int( var_h ) //Or ... var_i = floor( var_h )
var_1 = V * ( 1 - S )
var_2 = V * ( 1 - S * ( var_h - var_i ) )
var_3 = V * ( 1 - S * ( 1 - ( var_h - var_i ) ) )

if ( var_i == 0 ) { var_r = V ; var_g = var_3 ; var_b = var_1 }
else if ( var_i == 1 ) { var_r = var_2 ; var_g = V ; var_b = var_1 }
else if ( var_i == 2 ) { var_r = var_1 ; var_g = V ; var_b = var_3 }
else if ( var_i == 3 ) { var_r = var_1 ; var_g = var_2 ; var_b = V }
else if ( var_i == 4 ) { var_r = var_3 ; var_g = var_1 ; var_b = V }
else { var_r = V ; var_g = var_1 ; var_b = var_2 }

R = var_r * 255 //RGB results = From 0 to 255
G = var_g * 255
B = var_b * 255
}
}
RGB —> CMY
//RGB values = From 0 to 255

C = 1 - ( R / 255 )
M = 1 - ( G / 255 )
Y = 1 - ( B / 255 )
CMY —> RGB
R = ( 1 - C ) * 255
G = ( 1 - M ) * 255
B = ( 1 - Y ) * 255
CMY —> CMYK
var_K = 1

if ( C < var_K ) var_K = C
if ( M < var_K ) var_K = M
if ( Y < var_K ) var_K = Y

C = ( C - var_K ) / ( 1 - var_K )
M = ( M - var_K ) / ( 1 - var_K )
Y = ( Y - var_K ) / ( 1 - var_K )
K = var_K
CMYK —> CMY
C = ( C * ( 1 - K ) + K )
M = ( M * ( 1 - K ) + K )
Y = ( Y * ( 1 - K ) + K )
==========================================
RGB to HSV & HSV to RGB
// r,g,b values are from 0 to 1
// h = [0,360], s = [0,1], v = [0,1]
//                if s == 0, then h = -1 (undefined)
void RGBtoHSV( float r, float g, float b, float *h, float *s, float *v )
{
        float min, max, delta;
        min = MIN( r, g, b );
        max = MAX( r, g, b );
        *v = max;                                // v
        delta = max - min;
        if( max != 0 )
                *s = delta / max;                // s
        else {
                // r = g = b = 0                // s = 0, v is undefined
                *s = 0;
                *h = -1;
                return;
        }
        if( r == max )
                *h = ( g - b ) / delta;                // between yellow & magenta
        else if( g == max )
                *h = 2 + ( b - r ) / delta;        // between cyan & yellow
        else
                *h = 4 + ( r - g ) / delta;        // between magenta & cyan
        *h *= 60;                                // degrees
        if( *h < 0 )
                *h += 360;
}
void HSVtoRGB( float *r, float *g, float *b, float h, float s, float v )
{
        int i;
        float f, p, q, t;
        if( s == 0 ) {
                // achromatic (grey)
                *r = *g = *b = v;
                return;
        }
        h /= 60;                        // sector 0 to 5
        i = floor( h );
        f = h - i;                        // factorial part of h
        p = v * ( 1 - s );
        q = v * ( 1 - s * f );
        t = v * ( 1 - s * ( 1 - f ) );
        switch( i ) {
                case 0:
                        *r = v;
                        *g = t;
                        *b = p;
                        break;
                case 1:
                        *r = q;
                        *g = v;
                        *b = p;
                        break;
                case 2
                        *r = p;
                        *g = v;
                        *b = t;
                        break;
                case 3:
                        *r = p;
                        *g = q;
                        *b = v;
                        break;
                case 4:
                        *r = t;
                        *g = p;
                        *b = v;
                        break;
                default:                // case 5:
                        *r = v;
                        *g = p;
                        *b = q;
                        break;
        }
}
=========================================
RGB to YIQ & YIQ to RGB

The YIQ system is the color primary system adopted by National Television
System Committee (NTSC) for color TV broadcasting. The YIQ color solid
is made by a linear transformation of the RGB cube. Its purpose is to
exploit certain characteristics of the human eye to maximize the utilization
of a fixed bandwidth. The human visual system is more sensitive to changes
in luminance than to changes in hue or saturation, and thus a wider bandwidth
should be dedicated to luminance than to color information. Y is similar to
perceived luminance, I and Q carry color information and some luminance
information. The Y signal usually has 4.2 MHz bandwidth in a 525 line
system. Originally, the I and Q had different bandwidths (1.5 and 0.6 MHz)
, but now they commonly have the same bandwidth of 1 MHz.

Here is the RGB -> YIQ conversion:

    [ Y ]     [ 0.299   0.587   0.114 ] [ R ]
    [ I ]  =  [ 0.596  -0.275  -0.321 ] [ G ]
    [ Q ]     [ 0.212  -0.523   0.311 ] [ B ]

Here is the YIQ -> RGB conversion:

    [ R ]     [ 1   0.956   0.621 ] [ Y ]
    [ G ]  =  [ 1  -0.272  -0.647 ] [ I ]
    [ B ]     [ 1  -1.105   1.702 ] [ Q ]
================================================
RGB to XYZ & XYZ to RGB

RGB values in a particular set of primaries can be transformed to and
from CIE XYZ via a 3x3 matrix transform. These transforms involve
tristimulus values, that is a set of three linear-light components that
conform to the CIE color-matching functions. CIE XYZ is a special set of
tristimulus values. In XYZ, any color is represented as a set of positive
values.

To transform from XYZ to RGB (with D65 white point), the matrix transform
used is [3]:

   [ R ]   [  3.240479 -1.537150 -0.498535 ]   [ X ]
   [ G ] = [ -0.969256  1.875992  0.041556 ] * [ Y ]
   [ B ]   [  0.055648 -0.204043  1.057311 ]   [ Z ].

The range for valid R, G, B values is [0,1]. Note, this matrix has negative
coefficients. Some XYZ color may be transformed to RGB values that are
negative or greater than one. This means that not all visible colors can
be produced using the RGB system.

The inverse transformation matrix is as follows:

   [ X ]   [  0.412453  0.357580  0.180423 ]   [ R ] **
   [ Y ] = [  0.212671  0.715160  0.072169 ] * [ G ]
   [ Z ]   [  0.019334  0.119193  0.950227 ]   [ B ].

** February 20, 2000 - typo in this line of the matrix was corrected
(0.189423 to 0.180423), thanks to Michal Karczmarek, University of Toronto
================================================
http://www.cs.rit.edu/~ncs/color/t_convert.html

XYZ to CIE L*a*b* (CIELAB) & CIELAB to XYZ

CIE 1976 L*a*b* is based directly on CIE XYZ and is an attampt to linearize the perceptibility of color differences. The non-linear relations for L*, a*, and b* are intended to mimic the logarithmic response of the eye. Coloring information is referred to the color of the white point of the system, subscript n.

L* = 116 * (Y/Yn)^(1/3) - 16            for Y/Yn > 0.008856
L* = 903.3 * Y/Yn                    otherwise

a* = 500 * ( f(X/Xn) - f(Y/Yn) )
b* = 200 * ( f(Y/Yn) - f(Z/Zn) )
    where f(t) = t^(1/3)            for t > 0.008856
          f(t) = 7.787 * t + 16/116        otherwise

Here Xn, Yn and Zn are the tristimulus values of the reference white.
The reverse transformation (for Y/Yn > 0.008856) is

X = Xn * ( P + a* / 500 )^3
Y = Yn * P^3
Z = Zn * ( P - b* / 200 )^3
    where P = (L* + 16) / 116


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