PHP中的RGB到HSV

在PHP中，将RGB三元组转换为HSV值最直接的方法是什么？

Answer 1

<?php function RGB_TO_HSV ($R, $G, $B) // RGB Values:Number 0-255 { // HSV Results:Number 0-1 $HSL = array(); $var_R = ($R / 255); $var_G = ($G / 255); $var_B = ($B / 255); $var_Min = min($var_R, $var_G, $var_B); $var_Max = max($var_R, $var_G, $var_B); $del_Max = $var_Max - $var_Min; $V = $var_Max; if ($del_Max == 0) { $H = 0; $S = 0; } else { $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) $H++; if ($H>1) $H--; } $HSL['H'] = $H; $HSL['S'] = $S; $HSL['V'] = $V; return $HSL; } 

Answer 2

这是一个简单，直接的方法，返回HSV值作为度和百分比，这是什么Photoshop的颜色select器使用。

请注意，返回值不是四舍五入的，你可以自己做，如果需要的话。 请记住， H(360) == H(0) ，因此H值为359.5和更大应舍入为0

为学习目的大量logging。

 /** * Licensed under the terms of the BSD License. * (Basically, this means you can do whatever you like with it, * but if you just copy and paste my code into your app, you * should give me a shout-out/credit :) */ <?php function RGBtoHSV($R, $G, $B) // RGB values: 0-255, 0-255, 0-255 { // HSV values: 0-360, 0-100, 0-100 // Convert the RGB byte-values to percentages $R = ($R / 255); $G = ($G / 255); $B = ($B / 255); // Calculate a few basic values, the maximum value of R,G,B, the // minimum value, and the difference of the two (chroma). $maxRGB = max($R, $G, $B); $minRGB = min($R, $G, $B); $chroma = $maxRGB - $minRGB; // Value (also called Brightness) is the easiest component to calculate, // and is simply the highest value among the R,G,B components. // We multiply by 100 to turn the decimal into a readable percent value. $computedV = 100 * $maxRGB; // Special case if hueless (equal parts RGB make black, white, or grays) // Note that Hue is technically undefined when chroma is zero, as // attempting to calculate it would cause division by zero (see // below), so most applications simply substitute a Hue of zero. // Saturation will always be zero in this case, see below for details. if ($chroma == 0) return array(0, 0, $computedV); // Saturation is also simple to compute, and is simply the chroma // over the Value (or Brightness) // Again, multiplied by 100 to get a percentage. $computedS = 100 * ($chroma / $maxRGB); // Calculate Hue component // Hue is calculated on the "chromacity plane", which is represented // as a 2D hexagon, divided into six 60-degree sectors. We calculate // the bisecting angle as a value 0 <= x < 6, that represents which // portion of which sector the line falls on. if ($R == $minRGB) $h = 3 - (($G - $B) / $chroma); elseif ($B == $minRGB) $h = 1 - (($R - $G) / $chroma); else // $G == $minRGB $h = 5 - (($B - $R) / $chroma); // After we have the sector position, we multiply it by the size of // each sector's arc (60 degrees) to obtain the angle in degrees. $computedH = 60 * $h; return array($computedH, $computedS, $computedV); } ?>