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Image Functions
A helpful collection of image processing routines. Some convert between colour spaces and others process the image. Such as converting from RGB to HLS, converting hex colour strings to RGB arrays, colourising an image or producing a threshold limited version of an image, sepia tone an image, return a ranges of colours from one colour to another... and much more besides!
class.image.php
The main class file. This class does not need to be instantiated.
<?php
//
// class.image.php
// version 1.1.1, 2005-02-20
//
// Description
//
// A PHP library of helpful image processing methods. This class does not
// need to be instantiated.
//
// Author
//
// Andrew Collington, 2005
// php@amnuts.com, http://php.amnuts.com/
//
// Feedback
//
// There is message board at the following address:
//
// http://php.amnuts.com/forums/index.php
//
// Please use that to post up any comments, questions, bug reports, etc. You
// can also use the board to show off your use of the script.
//
// License
//
// This class is available free of charge for personal or non-profit work. If
// you are using it in a commercial setting, please contact php@amnuts.com for
// payment and licensing terms.
//
// Support
//
// If you like this script, or any of my others, then please take a moment
// to consider giving a donation. This will encourage me to make updates and
// create new scripts which I would make available to you. If you would like
// to donate anything, then there is a link from my website to PayPal.
//
// Examples
//
// $img = imagecreatefromjpeg('original.jpg');
// Image::colourise($img, '4c63f2');
// imagejpeg($img, 'processed.jpg', 90);
//
// $img = imagecreatefromjpeg('original.jpg');
// Image::threshold($img, 128);
// imagejpeg($img, 'processed.jpg', 90);
//
// $img = imagecreatefromjpeg('original.jpg');
// Image::greyscale($img);
// imagejpeg($img, 'processed.jpg', 90);
//
// $hex = '#45F2C3';
// $hls = Image::rgb2hls(Image::hex2rgb($hex));
// $hls[0] = 192;
// $hls[2] = 0.15;
// echo Image::rgb2hex(Image::hls2rgb($hls));
//
// print_r(Image::colourRange('#cccccc', '#ffffff', 10));
//
class Image
{
/**
* Gathers the GD version information
*
* Sometimes a check for the GD version like this:
*
* (function_exists('imagecreatetruecolor')) ? 2 : 1;
*
* can fail. This method retrieves the GD information based on what PHP
* reports to be installed. It can return the parsed version as an array,
* or just the major version if you want to do a simple check.
*
* @return int|array
* @param bool $justMajor
* @access public
*/
function getGDVersion($justMajor = true)
{
static $version = array();
if (empty($version)) {
ob_start();
phpinfo();
$buffer = ob_get_contents();
ob_end_clean();
if (preg_match('|<B>GD Version</B></td><TD ALIGN="left">([^<]*)</td>|i', $buffer, $matches)) {
$version = explode('.', $matches[1]);
} else if (preg_match('|GD Version </td><td class="v">bundled \(([^ ]*)|i', $buffer, $matches)) {
$version = explode('.', $matches[1]);
} else if (preg_match('|GD Version </td><td class="v">([^ ]*)|i', $buffer, $matches)) {
$version = explode('.', $matches[1]);
}
}
return ($justMajor) ? $version[0] : $version;
}
/**
* Return an RGB colour value array of the pixel at given location.
*
* The array is returned as: array(0 => r, 1 => g, 2 => b)
*
* @return array
* @param resource &$im a reference to the image
* @param int $x coordinate
* @param int $y coordinate
* @access public
*/
function getPixelRGB(&$im, $x, $y)
{
$rgb = imagecolorat($im, $x, $y);
return array(($rgb >> 16) & 0xFF, ($rgb >> 8) & 0xFF, $rgb & 0xFF);
}
/**
* A simple metric for colour distance in RGB space
*
* The arrays are expected to be of the format:
* array(0 => r, 1 => g, 2 => b)
*
* @return float
* @param array $rgb1
* @param array $rgb2
* @access public
*/
function colourDistance($rgb1, $rgb2)
{
return sqrt(3 * ($rgb2[0] - $rgb1[0]) * ($rgb2[0] - $rgb1[0]) + 4 * ($rgb2[1] - $rgb1[1]) *
($rgb2[1] - $rgb1[1]) + 2 * ($rgb2[2] - $rgb1[2]) * ($rgb2[2] - $rgb1[2]));
}
/**
* Convert a hex colour string into an rgb array.
*
* Handles colour string in the following formats:
*
* o #44FF55
* o 4FF55
* o #4F5
* o 4F5
*
* @return array
* @param string $hex
* @access public
*/
function hex2rgb($hex)
{
$hex = @preg_replace('/^#/', '', $hex);
if (strlen($hex) == 3) {
$v = explode(':', chunk_split($hex, 1, ':'));
return array(16 * hexdec($v[0]) + hexdec($v[0]), 16 * hexdec($v[1]) + hexdec($v[1]), 16 * hexdec($v[2]) + hexdec($v[2]));
} else {
$v = explode(':', chunk_split($hex, 2, ':'));
return array(hexdec($v[0]), hexdec($v[1]), hexdec($v[2]));
}
}
/**
* Convert an rgb array into a hex colour string.
*
* Handles colour string in the following formats:
*
* o #44FF55
* o 4FF55
* o #4F5
* o 4F5
*
* @return array
* @param string $hex
* @access public
*/
function rgb2hex($rgb, $adHash = true)
{
return sprintf("%s%02X%02X%02X", ($adHash ? '#' : ''), $rgb[0], $rgb[1], $rgb[2]);
}
/**
* Convert an RGB array into HLS colour space.
*
* Expects array(r, g, b) where r, g, b in [0,255]. The HLS array is
* returned as array(h, l, s) where h is in [0,360], l and s in [0,1].
*
* Function adapted from 'Computer Graphics: Principles and Practice',
* by Foley, van Dam, Feiner and Hughes. Chapter 13; Achromatic and
* Colored Light.
*
* @return array
* @param array $rgb
* @access public
*/
function rgb2hls($rgb)
{
for ($c=0; $c<3; $c++) {
$rgb[$c] = $rgb[$c] / 255;
}
$hls = array(0, 0, 0);
$max = max($rgb);
$min = min($rgb);
$hls[1] = ($max + $min) / 2;
if ($max == $min) {
$hls[0] = null;
$hls[2] = 0;
} else {
$delta = $max - $min;
$hls[2] = ($hls[1] <= 0.5) ? ($delta / ($max + $min)) : ($delta / (2 - ($max + $min)));
if ($rgb[0] == $max) {
$hls[0] = ($rgb[1] - $rgb[2]) / $delta;
} else if ($rgb[1] == $max) {
$hls[0] = 2 + ($rgb[2] - $rgb[0]) / $delta;
} else {
$hls[0] = 4 + ($rgb[0] - $rgb[1]) / $delta;
}
$hls[0] *= 60;
if ($hls[0] < 0) {
$hls[0] += 360;
}
if ($hls[0] > 360) {
$hls[0] -= 360;
}
}
ksort($hls);
return $hls;
}
/**
* Convert HLS colour space array to RGB colour space.
*
* Expects HLS array as array(h, l, s) where h in [0,360], l and s each
* in [0,1]. Returns array(r, g, b) where r, g, and b each in [0, 255]
*
* Function adapted from 'Computer Graphics: Principles and Practice',
* by Foley, van Dam, Feiner and Hughes. Chapter 13; Achromatic and
* Colored Light.
*
* @return array
* @param array $hls
* @access public
*/
function hls2rgb($hls)
{
$rgb = array(0, 0, 0);
$m2 = ($hls[1] <= 0.5) ? ($hls[1] * (1 + $hls[2])) : ($hls[1] + $hls[2] * (1 - $hls[1]));
$m1 = 2 * $hls[1] - $m2;
if (!$hls[2]) {
if ($hls[0] === null) {
$rgb[0] = $rgb[1] = $rgb[2] = $hls[1];
} else {
return false;
}
} else {
$rgb[0] = Image::_hVal($m1, $m2, $hls[0] + 120);
$rgb[1] = Image::_hVal($m1, $m2, $hls[0]);
$rgb[2] = Image::_hVal($m1, $m2, $hls[0] - 120);
}
for ($c=0; $c<3; $c++) {
$rgb[$c] = round($rgb[$c] * 255);
}
return $rgb;
}
/**
* Hue value checker for HSL colour space routine.
*
* @return float
* @param float $n1
* @param float $n2
* @param float $h
* @access private
* @see Image::hls2rgb()
*/
function _hVal($n1, $n2, $h)
{
if ($h > 360) {
$h -= 360;
} else if ($h < 0) {
$h += 360;
}
if ($h < 60) {
return $n1 + ($n2 - $n1) * $h / 60;
} else if ($h < 180) {
return $n2;
} else if ($h < 240) {
return $n1 + ($n2 - $n1) * (240 - $h) / 60;
} else {
return $n1;
}
}
/**
* Convert an RGB array into HSV (aka HSB) colour space.
*
* Expects array(r, g, b) where r, g, b in [0,255]. The HSV array is
* returned as array(h, s, v) where h is in [0,360], s and v in [0,1].
*
* Function adapted from 'Computer Graphics: Principles and Practice',
* by Foley, van Dam, Feiner and Hughes. Chapter 13; Achromatic and
* Colored Light.
*
* @return array
* @param array $rgb
* @access public
*/
function rgb2hsv($rgb)
{
for ($c=0; $c<3; $c++) {
$rgb[$c] = $rgb[$c] / 255;
}
$hsv = array(0, 0, 0);
$max = max($rgb);
$min = min($rgb);
$hsv[2] = $max;
$hsv[1] = ($max) ? (($max - $min) / $max) : 0;
if (!$hsv[1]) {
$hsv[0] = null;
} else {
$delta = $max - $min;
if ($rgb[0] == $max) {
$hsv[0] = ($rgb[1] - $rgb[2]) / $delta;
} else if ($rgb[1] == $max) {
$hsv[0] = 2 + ($rgb[2] - $rgb[0]) / $delta;
} else {
$hsv[0] = 4 + ($rgb[0] - $rgb[1]) / $delta;
}
$hsv[0] *= 60;
if ($hsv[0] < 0) {
$hsv[0] += 360;
}
}
ksort($hsv);
return $hsv;
}
/**
* Convert HSV colour space array to RGB colour space.
*
* Expects HLS array as array(h, s, v) where h in [0,360], s and v each
* in [0,1]. Returns array(r, g, b) where r, g, and b each in [0, 255]
*
* Function adapted from 'Computer Graphics: Principles and Practice',
* by Foley, van Dam, Feiner and Hughes. Chapter 13; Achromatic and
* Colored Light.
*
* @return array
* @param array $hsv
* @access public
*/
function hsv2rgb($hsv)
{
if (!$hsv[1]) {
if ($hsv[0] === null) {
$rgb[0] = $rgb[1] = $rgb[2] = $hsv[2];
} else {
return false;
}
} else {
if ($hsv[0] == 360) {
$hsv[0] = 0;
}
$hsv[0] /= 60;
$i = floor($hsv[0]);
$f = $hsv[0] - $i;
$p = $hsv[2] * (1 - $hsv[1]);
$q = $hsv[2] * (1 - ($hsv[1] * $f));
$t = $hsv[2] * (1 - ($hsv[1] * (1 - $f)));
switch ($i) {
case 0:
$rgb[0] = $hsv[2];
$rgb[1] = $t;
$rgb[2] = $p;
break;
case 1:
$rgb[0] = $q;
$rgb[1] = $hsv[2];
$rgb[2] = $p;
break;
case 2:
$rgb[0] = $p;
$rgb[1] = $hsv[2];
$rgb[2] = $t;
break;
case 3:
$rgb[0] = $p;
$rgb[1] = $q;
$rgb[2] = $hsv[2];
break;
case 4:
$rgb[0] = $t;
$rgb[1] = $p;
$rgb[2] = $hsv[2];
break;
case 5:
$rgb[0] = $hsv[2];
$rgb[1] = $p;
$rgb[2] = $q;
break;
}
}
for ($c=0; $c<3; $c++) {
$rgb[$c] = round($rgb[$c] * 255);
}
return $rgb;
}
/**
* Converts an image resource into a grey-scale version
*
* @return void
* @param resource &$im a reference to the image
* @access public
*/
function greyscale(&$im)
{
$sx = imagesx($im);
$sy = imagesy($im);
for ($x = 0; $x < $sx; $x++) {
for ($y = 0; $y < $sy; $y++) {
$rgb = Image::getPixelRGB($im, $x, $y);
$colour = ($rgb[0] + $rgb[1] + $rgb[2]) / 3;
imagesetpixel($im, $x, $y, imagecolorallocate($im, $colour, $colour, $colour));
}
}
}
/**
* Converts an image resource into a threshold black/white version.
*
* The threshold level is a value from 0 to 255 (black to white), and any
* pixel with a colour below that value will be turned black, and any
* pixel above that value will be turned white.
*
* @return void
* @param resource &$im a reference to the image
* @param int $level
* @access public
*/
function threshold(&$im, $level = 128)
{
$sx = imagesx($im);
$sy = imagesy($im);
$black = imagecolorallocate($im, 0, 0, 0);
$white = imagecolorallocate($im, 255, 255, 255);
for ($x = 0; $x < $sx; $x++) {
for ($y = 0; $y < $sy; $y++) {
$rgb = Image::getPixelRGB($im, $x, $y);
$intensity = ($rgb[0] + $rgb[1] + $rgb[2]) / 3;
imagesetpixel($im, $x, $y, ($intensity < $level ? $black : $white));
}
}
}
/**
* Colourises an image based on given colour.
*
* The colour to use as the shade/tint can be passed and as hex colour
* string or as an RGB array.
*
* @return void
* @param resource &$im a reference to the image
* @param string|array $setColour
* @access public
*/
function colourise(&$im, $setColour)
{
if (is_string($setColour)) {
$hls = Image::rgb2hls(Image::hex2rgb($setColour));
} else {
$hls = Image::rgb2hls($setColour);
}
$sx = imagesx($im);
$sy = imagesy($im);
for ($x = 0; $x < $sx; $x++) {
for ($y = 0; $y < $sy; $y++) {
$rgb = Image::getPixelRGB($im, $x, $y);
$pxhls = Image::rgb2hls($rgb);
$pxhls[0] = $hls[0];
$pxhls[2] = $hls[2];
$rgb = Image::hls2rgb($pxhls);
imagesetpixel($im, $x, $y, imagecolorallocate($im, $rgb[0], $rgb[1], $rgb[2]));
}
}
}
/**
* @see Image::colourise()
*/
function colorize(&$im, $setColour)
{
Image::colourise($im, $setColour);
}
/**
* Sepia tone an image.
*
* @return void
* @param resource &$im a reference to the image
* @access public
*/
function sepia(&$im)
{
$sx = imagesx($im);
$sy = imagesy($im);
for ($x = 0; $x < $sx; $x++) {
for ($y = 0; $y < $sy; $y++) {
$rgb = Image::getPixelRGB($im, $x, $y);
$pxhls = Image::rgb2hls($rgb);
$pxhls[0] = 0.30;
$pxhls[2] = 0.25;
$rgb = Image::hls2rgb($pxhls);
imagesetpixel($im, $x, $y, imagecolorallocate($im, $rgb[0], $rgb[1], $rgb[2]));
}
}
}
/**
* Get a range of colours over a certain number of steps,
*
* Given two different colours, this method will give you a range of
* colours over a certain number of steps from the first colour to the
* second. If the two input colours are in hex format, then the array
* returned will consist of hex values. If the two colours are passed
* as arrays, then the returned array will consist of arrays. If there
* is a mix of hex and rgb arrays then the returned array will also be
* returned in that format.
*
* If the $trueSteps parameter is true, then the range will go from
* colour one to colour two in $steps, returning $steps + 1 colours.
* If set to false, it will just return $steps colours (as most people
* might expect).
*
* @return array
* @param string|array $startColour
* @param string|array $endColour
* @param int $steps
* @param boolean $trueSteps
* @access public
*/
function colourRange($startColour, $endColour, $steps, $trueSteps = false)
{
$range = array();
$saveType = 0;
if (is_array($startColour) && is_array($endColour)) {
$saveType = 1;
} else if (is_string($startColour) && is_array($endColour)) {
$saveType = 2;
} else if (is_array($startColour) && is_string($endColour)) {
$saveType = 3;
}
$s = (is_string($startColour)) ? Image::hex2rgb($startColour) : $startColour;
$e = (is_string($endColour)) ? Image::hex2rgb($endColour) : $endColour;
if (!$trueSteps) {
--$steps;
}
for ($i = 0; $i <= $steps; $i++) {
$rgb = array();
$rgb[0] = round($s[0] + ($i * ($e[0] - $s[0]) / $steps));
$rgb[1] = round($s[1] + ($i * ($e[1] - $s[1]) / $steps));
$rgb[2] = round($s[2] + ($i * ($e[2] - $s[2]) / $steps));
switch($saveType) {
case 3:
$range[] = array($rgb, Image::rgb2hex($rgb));
break;
case 2:
$range[] = array(Image::rgb2hex($rgb), $rgb);
break;
case 1:
$range[] = $rgb;
break;
default:
$range[] = Image::rgb2hex($rgb);
break;
}
}
return $range;
}
/**
* @see Image::colourRange()
*/
function colorRange($startColour, $endColour, $steps, $trueSteps = false)
{
return Image::colourRange($startColour, $endColour, $steps, $trueSteps);
}
}
?>
17.73kb in size
last modified May 6, 2006 at 9:55pm
11263 views, 6454 downloads
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