在PHP中,将RGB三元组转换为HSV值的最直接方法是什么?
发布于 2009-11-21 06:59:31
<?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 $HSL;
}
发布于 2012-12-15 07:59:15
下面是一个简单、直接的方法,它将HSV值返回为度和百分比,这是Photoshop的颜色选择器所使用的。
请注意,返回值不是四舍五入的,如果需要,您可以自己执行此操作。请记住,H(360) == H(0)
,因此359.5
和更大的H
值应该舍入为0
为了学习目的,有大量的文档。
/**
* Licensed under the terms of the BSD License.
* (Basically, this means you can do whatever you like with it,
* but if you just copy and paste my code into your app, you
* should give me a shout-out/credit :)
*/
<?php
function RGBtoHSV($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, $computedV);
}
?>
发布于 2019-09-09 10:46:49
我是这样做的
function convertRgbToHsv($rgb)
{
$r = (int)substr($rgb, 0, 3) / 255;
$g = (int)substr($rgb, 3, 3) / 255;
$b = (int)substr($rgb, 6, 3) / 255;
$max = max($r, $g, $b);
$min = min($r, $g, $b);
$delta = $max - $min;
if (!$delta) {
$h = 0;
} else if ($r === $max) {
$h = 60 * ((($g - $b) / $delta) % 6);
} else if ($g === $max) {
$h = 60 * ((($b - $r) / $delta) + 2);
} else {
$h = 60 * ((($r - $g) / $delta) + 4);
}
$s = !!$max ? $delta / $max : 0;
$v = $max;
$hsv = array("h" => $h, "s" => $s, "v" => $v);
return $hsv;
}
链接到参考材料here
https://stackoverflow.com/questions/1773698
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