RGB to HSV in PHP
<?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;
}
PHP HSV to RGB formula comprehension
This is for the the HSV values in the range [0,1] (and giving RGB values in the range [0,1], instead of {0, 1, ..., 255}:
function HSVtoRGB(array $hsv) {
list($H,$S,$V) = $hsv;
//1
$H *= 6;
//2
$I = floor($H);
$F = $H - $I;
//3
$M = $V * (1 - $S);
$N = $V * (1 - $S * $F);
$K = $V * (1 - $S * (1 - $F));
//4
switch ($I) {
case 0:
list($R,$G,$B) = array($V,$K,$M);
break;
case 1:
list($R,$G,$B) = array($N,$V,$M);
break;
case 2:
list($R,$G,$B) = array($M,$V,$K);
break;
case 3:
list($R,$G,$B) = array($M,$N,$V);
break;
case 4:
list($R,$G,$B) = array($K,$M,$V);
break;
case 5:
case 6: //for when $H=1 is given
list($R,$G,$B) = array($V,$M,$N);
break;
}
return array($R, $G, $B);
}
PHP function to convert HSL to RGB or Hex
Taking the code from one of the answers in the link of Jim's comment (PHP HSV to RGB formula comprehension), we can compute it as follows:
<?php
$hue = 209;
$sat = 75;
$lum = 60;
$hue /= 360;
$sat /= 100;
$lum /= 100;
$result = ColorHSLToRGB($hue, $sat, $lum);
var_dump($result); echo '<br>';
printf("rgb = %d,%d,%d<br>", $result['r'], $result['g'], $result['b']);
function ColorHSLToRGB($h, $s, $l){
$r = $l;
$g = $l;
$b = $l;
$v = ($l <= 0.5) ? ($l * (1.0 + $s)) : ($l + $s - $l * $s);
if ($v > 0){
$m;
$sv;
$sextant;
$fract;
$vsf;
$mid1;
$mid2;
$m = $l + $l - $v;
$sv = ($v - $m ) / $v;
$h *= 6.0;
$sextant = floor($h);
$fract = $h - $sextant;
$vsf = $v * $sv * $fract;
$mid1 = $m + $vsf;
$mid2 = $v - $vsf;
switch ($sextant)
{
case 0:
$r = $v;
$g = $mid1;
$b = $m;
break;
case 1:
$r = $mid2;
$g = $v;
$b = $m;
break;
case 2:
$r = $m;
$g = $v;
$b = $mid1;
break;
case 3:
$r = $m;
$g = $mid2;
$b = $v;
break;
case 4:
$r = $mid1;
$g = $m;
$b = $v;
break;
case 5:
$r = $v;
$g = $m;
$b = $mid2;
break;
}
}
return array('r' => $r * 255.0, 'g' => $g * 255.0, 'b' => $b * 255.0);
}
?>
Output:
array(3) { ["r"]=> float(76.5) ["g"]=> float(155.55) ["b"]=> float(229.5) }
rgb = 76,155,229
Algorithm to generate RGB graduated colors in PHP
In the following image you can see the output of a piece of code I wrote to compare transitions between two colors using RGB and HSV splitting in equal size steps:
I found the transitions using HSV are afected by Hue and depend of the distance between colors. If you choose two colors with the same hue is interesting to see that HSV transitions are more clear than in RGB, because you are only playing with saturation and value (black) and no adding colors like in RGB.
<?php
// Configuration.
$nc = 6; // Number of colors.
$w = 300; // Width of divs.
$a = 50; // Height of divs.
// Colors
/* In RGB */
$c1 = array(rand(0,255),rand(0,255),rand(0,255));
$c2 = array(rand(0,255),rand(0,255),rand(0,255));
//$c1 = array(128,175,27); // Color 1: Whit these colors is not change.
//$c2 = array(255,255,140); // Color 2: Whit these colors is not change.
// $c1 = array(0,0,0); // Color 1: White.
// $c2 = array(255,255,255); // Color 2: Black.
/* In HSV */
$h3 = array(rand(0,360),rand(0,100),rand(0,100));
$h4 = array(rand(0,360),rand(0,100),rand(0,100));
//$h3 = array(145,50,50); // Color 3: To see the influence of Hue.
//$h4 = array(145,0,100); // Color 4: To see the influence of Hue.
// HTML
$html .= '<div style="margin:auto;width:'.($w*2).'px;">';
// RGB to RGB split
$c = graduateRGB($c1,$c2,$nc);
$html .= customHTML($w,$a,$c,'RGB->RGBs');
// RGB to HSV split
$h1 = RGBtoHSV($c1);
$h2 = RGBtoHSV($c2);
$h = graduateHSV($h1,$h2,$nc);
$html .= customHTML($w,$a,$h,'RGB->HSVs');
// HSV to HSV split
$h = graduateHSV($h3,$h4,$nc);
$html .= customHTML($w,$a,$h,'HSV->HSVs');
// HSV to RGB split
$c3 = HSVtoRGB($h3);
$c4 = HSVtoRGB($h4);
$c = graduateRGB($c3,$c4,$nc);
$html .= customHTML($w,$a,$c,'HSV->RGBs');
// Output
$html .= '</div>';
echo $html;
/* FUNCIONES DE GRADUACIÓN */
// Dados dos colores RGB (0-255,0-255,0-255) y un número de colores deseados, regresa un array con todos los colores de la gradación.
function graduateRGB($c1,$c2,$nc){
$c = array();
$dc = array(($c2[0]-$c1[0])/($nc-1),($c2[1]-$c1[1])/($nc-1),($c2[2]-$c1[2])/($nc-1));
for ($i=0;$i<$nc;$i++){
$c[$i][0]= round($c1[0]+$dc[0]*$i);
$c[$i][1]= round($c1[1]+$dc[1]*$i);
$c[$i][2]= round($c1[2]+$dc[2]*$i);
}
return $c;
}
// Dados dos colores HSV (0-360,0-100,0-100) y un número de colores deseados, regresa un array con todos los colores de la gradación en RGB. (Hay un detalle con esta función y es que la transición se podría hacer por el lado contrario del círculo cromático)
function graduateHSV($h1,$h2,$nc){
$h = array();
$dh = array(($h2[0]-$h1[0])/($nc-1),($h2[1]-$h1[1])/($nc-1),($h2[2]-$h1[2])/($nc-1));
for ($i=0;$i<$nc;$i++){
$h[$i][0]= $h1[0]+$dh[0]*$i;
$h[$i][1]= $h1[1]+$dh[1]*$i;
$h[$i][2]= $h1[2]+$dh[2]*$i;
$h[$i] = HSVtoRGB($h[$i]);
}
return $h;
}
/* FUNCIONES DE CONVERSIÓN. */
// Convierte a HSV (0-360,0-100,0-100) colores en RGB (0-255,0-255,0-255).
function RGBtoHSV(array $rgb) {
$f = 0.00000001; // Factor de corrección para evitar la división por cero.
list($R,$G,$B) = $rgb;
$R = $R==0?$f:$R/255;
$G = $G==0?$f:$G/255;
$B = $B==0?$f:$B/255;
$V = max($R,$G,$B);
$X = min($R,$G,$B);
$S = ($V-$X)/$V;
$V_X = $V-$X==0?$f:$V-$X;
$r = ($V-$R)/($V_X);
$g = ($V-$G)/($V_X);
$b = ($V-$B)/($V_X);
if ($R == $V)
$H = $G==$X?(5+$b):(1-$g);
elseif ($G == $V)
$H = $B==$X?(1+$r):(3-$b);
else
$H = $R==$X?(3+$g):(5-$r);
$H /= 6;
$H = round($H*360);
$S = round($S*100);
$V = round($V*100);
return array($H, $S, $V);
}
// Convierte a RGB (0-255,0-255,0-255) colores en HSV (0-360,0-100,0-100).
function HSVtoRGB(array $hsv) {
list($H,$S,$V) = $hsv;
$H = $H/360;
$S = $S/100;
$V = $V/100;
//1
$H *= 6;
//2
$I = floor($H);
$F = $H - $I;
//3
$M = $V * (1 - $S);
$N = $V * (1 - $S * $F);
$K = $V * (1 - $S * (1 - $F));
//4
switch ($I) {
case 0:
list($R,$G,$B) = array($V,$K,$M);
break;
case 1:
list($R,$G,$B) = array($N,$V,$M);
break;
case 2:
list($R,$G,$B) = array($M,$V,$K);
break;
case 3:
list($R,$G,$B) = array($M,$N,$V);
break;
case 4:
list($R,$G,$B) = array($K,$M,$V);
break;
case 5:
case 6: //for when $H=1 is given
list($R,$G,$B) = array($V,$M,$N);
break;
}
$R = round($R*255);
$G = round($G*255);
$B = round($B*255);
return array($R, $G, $B);
}
// Función con un HTML de muestra para la visualización de colores, podría ser cualquier otro.
function customHTML($w,$a,$c,$header){
$html = '<div style="float:left;text-align:center;"><h2>'.$header.'</h2>';
foreach ($c as $color){
$html .= '<div style="width:'.$w.'px;height:'.$a.'px;background-color:rgb('.$color[0].','.$color[1].','.$color[2].');">RGB '.$color[0].','.$color[1].','.$color[2].'</div>';
}
$html .= '</div>';
return $html;
}
?>
PHP Work out colour saturation
See RGB to HSV in PHP
Taking only the saturation bits from that code, and converting into a percentage:
function saturation($R, $G, $B) { // 0-255
$Min = min($R, $G, $B);
$Max = max($R, $G, $B);
return $Max == 0 ? 0 : (($Max - $Min) / $Max) * 100;
}
Alternately you could use the original code in the link above - the HSV values it returns are between 0.0 and 1.0, so you just need to multiply the saturation value by 100 to get your percentage.
How to detect light colors with PHP
Transform HTML colour to RGB, then to Hue-Saturation-Lightnes (HSV)
<?php
function HTMLToRGB($htmlCode)
{
if($htmlCode[0] == '#')
$htmlCode = substr($htmlCode, 1);
if (strlen($htmlCode) == 3)
{
$htmlCode = $htmlCode[0] . $htmlCode[0] . $htmlCode[1] . $htmlCode[1] . $htmlCode[2] . $htmlCode[2];
}
$r = hexdec($htmlCode[0] . $htmlCode[1]);
$g = hexdec($htmlCode[2] . $htmlCode[3]);
$b = hexdec($htmlCode[4] . $htmlCode[5]);
return $b + ($g << 0x8) + ($r << 0x10);
}
function RGBToHSL($RGB) {
$r = 0xFF & ($RGB >> 0x10);
$g = 0xFF & ($RGB >> 0x8);
$b = 0xFF & $RGB;
$r = ((float)$r) / 255.0;
$g = ((float)$g) / 255.0;
$b = ((float)$b) / 255.0;
$maxC = max($r, $g, $b);
$minC = min($r, $g, $b);
$l = ($maxC + $minC) / 2.0;
if($maxC == $minC)
{
$s = 0;
$h = 0;
}
else
{
if($l < .5)
{
$s = ($maxC - $minC) / ($maxC + $minC);
}
else
{
$s = ($maxC - $minC) / (2.0 - $maxC - $minC);
}
if($r == $maxC)
$h = ($g - $b) / ($maxC - $minC);
if($g == $maxC)
$h = 2.0 + ($b - $r) / ($maxC - $minC);
if($b == $maxC)
$h = 4.0 + ($r - $g) / ($maxC - $minC);
$h = $h / 6.0;
}
$h = (int)round(255.0 * $h);
$s = (int)round(255.0 * $s);
$l = (int)round(255.0 * $l);
return (object) Array('hue' => $h, 'saturation' => $s, 'lightness' => $l);
}
$colour = '#F12346';
$rgb = HTMLToRGB($colour);
$hsl = RGBToHSL($rgb);
var_dump($hsl);
Usage:
$colour = '#F12346';
$rgb = HTMLToRGB($colour);
$hsl = RGBToHSL($rgb);
if($hsl->lightness > 200) {
// this is light colour!
}
Source:
- http://www.caperna.org/computing/repository/hsl-rgb-color-conversion-php
Demo:
- http://codepad.org/X7KV4n4n
Altering Saturation of #RGB Color: Whats Missing Here?
Saturation and brightness cannot be handled the same (one could argue that your aren't handling brightness correctly using this code but it's probably close enough). See this question RGB to HSV in PHP for how to convert the color to an HSV value then you can modify the saturation (the S value). Then convert back using the answer to this question PHP HSV to RGB.
Related Topics
How to Install/Enable the PHP Phar Extension
Call a C Program from PHP and Read Program Output
Composer Installing: the JSON Extension Is Missing
Executing a Shell Script in Background with PHP
Package 'Php5-Gd' Has No Installation Candidate
Can't Install PHP Package on Centos
Naming Convention Issues When Using Codeigniter in Windows and Linux
Why We Need Curlopt_Ssl_Verifypeer in Windows
How to Check If There Is a There Is a Wget Instance Running
PHP Failed to Open Stream: Is a Directory
Centos 7/Apache/PHP - Mkdir(): Permission Denied
Execute Commands on Remote MAChine via PHP
How to Chain Method on a Newly Created Object
How to Send Email from Localhost Wamp Server to Send Email Gmail Hotmail or So Forth
How to Use Pdo's Prepared Statement for Order by and Limit Clauses