imagecharup
Here's a very simple function that basically does the same as imagecolorallocate(), only without needing an image resource to work.
<?php
function createcolor($r, $g, $b) {
return hexdec(str_pad(dechex($r), 2, 0, STR_PAD_LEFT).str_pad(dechex($g), 2, 0, STR_PAD_LEFT).str_pad(dechex($b), 2, 0, STR_PAD_LEFT));
}
/* As said earlier, this function does the exact same thing as imagecolorallocate(), without needing an image resource. This means that the following two blocks of code result in the exact same thing: */
//Block 1
$color = colorcreate(105, 199, 204);
//Block 2
$img = imagecreatetruecolor(100, 100); //the arguments here don't really matter
$color = imagecolorallocate($img, 105, 199, 204);
imagedestroy($img);
?>
imagecolorallocate
(PHP 4, PHP 5)
imagecolorallocate — 为一幅图像分配颜色
说明
int imagecolorallocate
( resource $image
, int $red
, int $green
, int $blue
)
imagecolorallocate() 返回一个标识符，代表了由给定的 RGB 成分组成的颜色。red ，green 和 blue 分别是所需要的颜色的红，绿，蓝成分。这些参数是 0 到 255 的整数或者十六进制的 0x00 到 0xFF。imagecolorallocate() 必须被调用以创建每一种用在 image 所代表的图像中的颜色。
Note: 第一次对 imagecolorallocate() 的调用会给基于调色板的图像填充背景色，即用 imagecreate() 建立的图像。
Example#1 imagecolorallocate() 例子
<?php
$im = imagecreate('example.jpg', 100, 100);
// 背景设为红色
$background = imagecolorallocate($im, 255, 0, 0);
// 设定一些颜色
$white = imagecolorallocate($im, 255, 255, 255);
$black = imagecolorallocate($im, 0, 0, 0);
// 十六进制方式
$white = imagecolorallocate($im, 0xFF, 0xFF, 0xFF);
$black = imagecolorallocate($im, 0x00, 0x00, 0x00);
?>
如果分配失败则返回 -1。
add a note
User Contributed Notesimagecolorallocate
shinesoldier at gmail dot com
07-May-2009 07:16
07-May-2009 07:16
federicot at gmail dot com
21-May-2008 10:08
21-May-2008 10:08
Little correction to marc-gutt's regural expression to validate hex color values. You can use this little function:
<?php
// Validate an hex color string. Return true if valid, false otherwise
function validateHexColor($color) {
$color = substr($color, 0, 7);
return preg_match('/#[0-9a-fA-F]{6}/', $color);
}
?>
djcassis at gmail dot com
22-Nov-2007 04:06
22-Nov-2007 04:06
I also find the following useful when dealing with HTML hexadecimal colors :
<?php
$color = '#FFffFF';
print_r(sscanf($color, '#%2x%2x%2x'));
?>
outputs :
Array
(
[0] => 255
[1] => 255
[2] => 255
)
Ludo
25-Oct-2007 05:35
25-Oct-2007 05:35
When working on an existant GIF images, if the number of different colours has reached the limits of the GIF format, imagecolorallocate will not use to the colour you ask her within the parameters, she will apply black !
That's a problem when generating images "on-the-fly" with many manipulations, from a GIF image.
To go round the problem, you have to convert the GIF image into a PNG one, and then you can work on the PNG and everything will be ok.
For example :
<?php
// first, convert into a PNG image
$handle = imagecreatefromgif('my_image.gif');
imagepng($handle, 'my_image.png');
imagedestroy($handle);
// then, you can work on it
$handle = imagecreatefrompng('my_image.png');
/*
* work on the image
*/
imagegif($handle);
?>
William Barath
29-Sep-2007 07:15
29-Sep-2007 07:15
Lots of hsv2rgb commentary but no working example, so here's mine:
<?php // hsv2rgb example translated from ImageMagick C code
function hsv2rgb($h, $s, $v)
{
$s /= 256.0;
if ($s == 0.0) return array($v,$v,$v);
$h /= (256.0 / 6.0);
$i = floor($h);
$f = $h - $i;
$p = (integer)($v * (1.0 - $s));
$q = (integer)($v * (1.0 - $s * $f));
$t = (integer)($v * (1.0 - $s * (1.0 - $f)));
switch($i) {
case 0: return array($v,$t,$p);
case 1: return array($q,$v,$p);
case 2: return array($p,$v,$t);
case 3: return array($p,$q,$v);
case 4: return array($t,$p,$v);
default: return array($v,$p,$q);
}
}
$image = ImageCreateTrueColor(256,128);
for ($y=0; $y<64; $y++) for($x=0; $x<256; $x++){
list($r,$g,$b) = hsv2rgb($x | 7,255,($y*4) |7);
$color = ($r << 16 ) | ($g << 8) | $b;
imagesetpixel($image, $x, $y-4, $color);
}
for ($y=64; $y<128; $y++) for($x=0; $x<256; $x++){
list($r,$g,$b) = hsv2rgb($x|7,((127-$y)*4)|7,255);
$color = ($r << 16) | ($g << 8) | $b;
imagesetpixel($image, $x, $y-4, $color);
}
for ($y=120; $y<128; $y++) for($x=0; $x<256; $x++){
$color = (($x |7) << 16) | (($x |7) << 8) | ($x |7);
imagesetpixel($image, $x, $y, $color);
}
header("Content-Type: image/png");
imagepng($image);
?>
info at marc-gutt dot de Marc Gutt
04-Aug-2007 08:50
04-Aug-2007 08:50
rgb from hex without creating a new function or using split features:
<?php
$color = 'FF9900';
$color = imagecolorallocate($im, hexdec('0x' . $color{0} . $color{1}), hexdec('0x' . $color{2} . $color{3}), hexdec('0x' . $color{4} . $color{5}));
?>
You can validate $color with preg_match('#[a-z0-9]{6}#i', $color) if necessary.
picklecj at rose-hulman dot edu
13-Jun-2007 11:15
13-Jun-2007 11:15
Another solution to color limitation issues when creating gradients. This file takes width (px) and left and right colors (hex) and makes a gradient while only allocating 250 colors.
<?php
$leftR = hexdec(substr($_GET["left"],0,2));
$leftG = hexdec(substr($_GET["left"],2,2));
$leftB = hexdec(substr($_GET["left"],4,2));
$rightR = hexdec(substr($_GET["right"],0,2));
$rightG = hexdec(substr($_GET["right"],2,2));
$rightB = hexdec(substr($_GET["right"],4,2));
$image=imagecreate($_GET["width"],1);
for($i=0;$i<250;$i++) {
$colorset[$i] = imagecolorallocate($image, $leftR + ($i*(($rightR-$leftR)/250)), $leftG + ($i*(($rightG-$leftG)/250)), $leftB + ($i*(($rightB-$leftB)/250)));
}
for($i=0;$i<($_GET["width"]);$i++) {
imagesetpixel ($image, $i, 0, $colorset[(int)($i/($_GET["width"]/250))] );
}
header("Content-type: image/png");
imagepng($image);
imagedestroy($image);
?>
example: gradient.php?width=640&left=000000&right=FF0000
Makes a 640px-wide image that fades from black to red.
LPEspecial at home dot nl
19-Sep-2006 11:04
19-Sep-2006 11:04
This might help someone who want to use 'ImageColorAllocate ' with a hex value
<?php
function ImageColorAllocateFromHex ($img, $hexstr)
{
$int = hexdec($hexstr);
return ImageColorAllocate ($img,
0xFF & ($int >> 0x10),
0xFF & ($int >> 0x8),
0xFF & $int);
}
?>
behun at webconsult dot sk
27-Aug-2006 04:56
27-Aug-2006 04:56
Also, when you need more then 256 colors, use imagecreatetruecolor function. With this function you can use unlimited number of colors.
SW
14-Jan-2006 06:00
14-Jan-2006 06:00
This works! A Black-Image with vertical centered white Aliased Arial-Text and same left and right margin - used for Menu-Buttons.
<?php
function createImgText ($string="", $fontsize=0, $marginX=0, $imgH=0 , $fontfile="", $imgColorHex="", $txtColorHex=""){
if($string!=""){
Header("Content-type: image/png");
//
$spacing = 0;
$line = array("linespacing" => $spacing);
$box = @imageftbbox($fontsize,0,$fontfile,$string,$line)
or die("ERROR");
$tw=$box[4]-$box[0]; //image width
$marginY = $imgH - (($imgH - $fontsize) / 2);
$imgWidth = $tw + (2*$marginX);
$im = ImageCreate($imgWidth, $imgH);
$int = hexdec($imgColorHex);
$arr = array("red" => 0xFF & ($int >> 0x10),
"green" => 0xFF & ($int >> 0x8),
"blue" => 0xFF & $int);
$black = ImageColorAllocate($im, $arr["red"], $arr["green"], $arr["blue"]);
$int = hexdec($txtColorHex);
$arr = array("red" => 0xFF & ($int >> 0x10),
"green" => 0xFF & ($int >> 0x8),
"blue" => 0xFF & $int);
$white = ImageColorAllocate($im, $arr["red"], $arr["green"], $arr["blue"]);
ImageFtText($im, $fontsize, 0, $marginX, $marginY, $white, $fontfile, $string, array());
ImagePng($im);
ImageDestroy($im);
}else{
echo "ERROR!";
}
}
createImgText ("Hello World", 9, 10, 18, "arial.ttf", "000000", "FFFFFF");
?>
mlse
15-Nov-2005 05:49
15-Nov-2005 05:49
Another more general variation on the theme using the same naming conventions as the hexdec and dechex built-in functions ...
Prototype:
array hexrgb ( string hex_string )
Returns:
An associative array of the RGB components specified in hex_string.
hexrgb() example:
<?php
$rgb = hexrgb("0xAABBCC");
print_r($rgb);
?>
Output is:
Array
(
[red] => 170
[green] => 187
[blue] => 204
)
Implementation:
<?php
function hexrgb ($hexstr)
{
$int = hexdec($hexstr);
return array("red" => 0xFF & ($int >> 0x10),
"green" => 0xFF & ($int >> 0x8),
"blue" => 0xFF & $int);
}
?>
The output of hexdec can then be passed to imagecolorallocate and manipulated as required.
Zigbigidorlu at hotmail dot com
07-Oct-2005 03:05
07-Oct-2005 03:05
Here's a very simple and very effective code to change a HEX color to RGB.
<?php
function HEX2RGB($color){
$color_array = array();
$hex_color = strtoupper($color);
for($i = 0; $i < 6; $i++){
$hex = substr($hex_color,$i,1);
switch($hex){
case "A": $num = 10; break;
case "B": $num = 11; break;
case "C": $num = 12; break;
case "D": $num = 13; break;
case "E": $num = 14; break;
case "F": $num = 15; break;
default: $num = $hex; break;
}
array_push($color_array,$num);
}
$R = (($color_array[0] * 16) + $color_array[1]);
$G = (($color_array[2] * 16) + $color_array[3]);
$B = (($color_array[4] * 16) + $color_array[5]);
return array($R,$G,$B);
unset($color_array,$hex,$R,$G,$B);
}
?>
mail at kailashnadh dot name
28-Jun-2005 10:47
28-Jun-2005 10:47
This nifty function will produce the negative of a given image!
<?php
/********************************
Code by Kailash Nadh
http://kailashnadh.name
usage:
img2neg("my_pic.jpg");
*********************************/
function img2neg($pic) {
header("Content-type: image/jpeg");
$source=imagecreatefromjpeg($pic); // Source
$width=imagesx($source); $height=imagesy($source);
$im = imagecreatetruecolor($width, $height); // Our negative img in the making
for($y=0; $y < $height; $y++) {
for($x=0; $x < $width; $x++) {
$colors=imagecolorsforindex($source, imagecolorat($source, $x,$y));
// this is what makes the colors negative
$r=255-$colors['red'];
$g=255-$colors['green'];
$b=255-$colors['blue'];
$test=imagecolorallocate($im, $r,$g,$b);
imagesetpixel($im,$x, $y, $test);
}
}
imagejpeg($im);
imagedestroy($im);
}
?>
andreoli dot carlo at libero dot it
08-Jun-2005 09:38
08-Jun-2005 09:38
hsl to RGB
(not yet optimized but it function)
<?php
function hslToRgb ($h, $s, $l) {
if ($h>240 || $h<0) return array(0,0,0);
if ($s>240 || $s<0) return array(0,0,0);
if ($l>240 || $l<0) return array(0,0,0);
if ($h<=40) {
$R=255;
$G=(int)($h/40*256);
$B=0;
}
elseif ($h>40 && $h<=80) {
$R=(1-($h-40)/40)*256;
$G=255;
$B=0;
}
elseif ($h>80 && $h<=120) {
$R=0;
$G=255;
$B=($h-80)/40*256;
}
elseif ($h>120 && $h<=160) {
$R=0;
$G=(1-($h-120)/40)*256;
$B=255;
}
elseif ($h>160 && $h<=200) {
$R=($h-160)/40*256;
$G=0;
$B=255;
}
elseif ($h>200) {
$R=255;
$G=0;
$B=(1-($h-200)/40)*256;
}
$R=$R+(240-$s)/240*(128-$R);
$G=$G+(240-$s)/240*(128-$G);
$B=$B+(240-$s)/240*(128-$B);
if ($l<120) {
$R=($R/120)*$l;
$G=($G/120)*$l;
$B=($B/120)*$l;
}
else {
$R=$l*((256-$R)/120)+2*$R-256;
$G=$l*((256-$G)/120)+2*$G-256;
$B=$l*((256-$B)/120)+2*$B-256;
}
if ($R<0) $R=0;
if ($R>255) $R=255;
if ($G<0) $G=0;
if ($G>255) $G=255;
if ($B<0) $B=0;
if ($B>255) $B=255;
return array((int)$R,(int)$G,(int)$B);
}
?>
mv at brazil dot com
16-Mar-2005 03:34
16-Mar-2005 03:34
<?php
/**
* Create a image bar using lib GD
* Ege. <img src="color_sample.php?color=FF0000" width="10 height="30">
*/
// Split the HTML color representation
$hexcolor = str_split($_GET["color"], 2);
// Convert HEX values to DECIMAL
$bincolor[0] = hexdec("0x{$hexcolor[0]}");
$bincolor[1] = hexdec("0x{$hexcolor[1]}");
$bincolor[2] = hexdec("0x{$hexcolor[2]}");
$im = ImageCreate(100, 100);
$colorallocate = ImageColorAllocate($im, $bincolor[0], $bincolor[1], $bincolor[2]);
ImageFilledRectangle($im, 0, 0, 100, 100, $colorallocate);
header('Content-Type: image/png');
ImagePNG($im);
?>
19-Jan-2005 06:23
When you are using truecolor images, you can also use bitwise operations to generate the color:
<?php
$color = ($r << 16) | ($g << 8) | $b; // 2261213
?>
This is identical to the imagecolorallocate() function, in truecolor images!
aaron at parecki dot com
22-Dec-2004 06:10
22-Dec-2004 06:10
This will let you tint an image to any specific color. The blacks of the source image become your specified color, and the whites remain white. Works best for colorizing greyscale images.
<?php
$r = 224;
$g = 192;
$b = 0;
$source_file = "picture.jpg";
$im_src = ImageCreateFromJpeg($source_file);
$im_tint = ImageCreate(imagesx($im_src),imagesy($im_src));
for ($c = 0; $c < 255; $c++) {
ImageColorAllocate($im_tint, max($r,$c), max($g,$c), max($b,$c));
}
ImageCopyMerge($im_tint,$im_src,0,0,0,0, imagesx($im_src), imagesy($im_src), 100);
ImageDestroy($im_src);
header("Content-type: image/jpeg");
imagejpeg($im_tint);
?>
tyberis
28-Nov-2004 08:58
28-Nov-2004 08:58
2 functions to convert from HSV colorspace (hue/saturation/brightness) to RGB (red/green/blue) colorspace and back.
<?php
// $c = array($red, $green, $blue)
// $red=[0..1], $green=[0..1], $blue=[0..1];
function rgb2hsv($c) {
list($r,$g,$b)=$c;
$v=max($r,$g,$b);
$t=min($r,$g,$b);
$s=($v==0)?0:($v-$t)/$v;
if ($s==0)
$h=-1;
else {
$a=$v-$t;
$cr=($v-$r)/$a;
$cg=($v-$g)/$a;
$cb=($v-$b)/$a;
$h=($r==$v)?$cb-$cg:(($g==$v)?2+$cr-$cb:(($b==$v)?$h=4+$cg-$cr:0));
$h=60*$h;
$h=($h<0)?$h+360:$h;
}
return array($h,$s,$v);
}
// $c = array($hue, $saturation, $brightness)
// $hue=[0..360], $saturation=[0..1], $brightness=[0..1]
function hsv2rgb($c) {
list($h,$s,$v)=$c;
if ($s==0)
return array($v,$v,$v);
else {
$h=($h%=360)/60;
$i=floor($h);
$f=$h-$i;
$q[0]=$q[1]=$v*(1-$s);
$q[2]=$v*(1-$s*(1-$f));
$q[3]=$q[4]=$v;
$q[5]=$v*(1-$s*$f);
//return(array($q[($i+4)%5],$q[($i+2)%5],$q[$i%5]));
return(array($q[($i+4)%6],$q[($i+2)%6],$q[$i%6])); //[1]
}
}
?>
[1] - EDITOR NOTE: THIS IS A FIX FROM "hc at hob(removethis)soft dot net".
smoli at paranoya dot ch
20-Jul-2004 02:10
20-Jul-2004 02:10
Some of you maybe want to use HSV color model for drawing color selectors and circles:
<?php
function &colormap_hsv_to_rgb($h, $s, $v)
{
$ret = new stdClass();
if($s == 0)
{
$ret->r = $v;
$ret->g = $v;
$ret->b = $v;
return $ret;
}
else
{
$h = floatval($h) / 255.0;
$s = floatval($s) / 255.0;
$v = floatval($v) / 255.0;
$hue = $h;
if($hue == 1.0)
$hue = 0.0;
$hue *= 6.0;
$i = intval($hue);
$f = $hue - floatval($i);
$w = $v * (1.0 - $s);
$q = $v * (1.0 - ($s * $f));
$t = $v * (1.0 - ($s * (1.0 - $f)));
switch($i)
{
case 0: $ret->r = $v; $ret->g = $t; $ret->b = $w; break;
case 1: $ret->r = $q; $ret->g = $v; $ret->b = $w; break;
case 2: $ret->r = $w; $ret->g = $v; $ret->b = $t; break;
case 3: $ret->r = $w; $ret->g = $q; $ret->b = $v; break;
case 4: $ret->r = $t; $ret->g = $w; $ret->b = $v; break;
case 5: $ret->r = $v; $ret->g = $w; $ret->b = $q; break;
}
}
$ret->r = intval($ret->r * 255.0);
$ret->g = intval($ret->g * 255.0);
$ret->b = intval($ret->b * 255.0);
return $ret;
}
?>
jernberg at fairytale dot se
06-Mar-2004 02:43
06-Mar-2004 02:43
this might help someone, how to allocate an color from an html color-definition:
<?php
$fg = "#ff0080";
$red = 100;
$green = 100;
$blue = 100;
if( eregi( "[#]?([0-9a-f]{2})([0-9a-f]{2})([0-9a-f]{2})", $fg, $ret ) )
{
$red = hexdec( $ret[1] );
$green = hexdec( $ret[2] );
$blue = hexdec( $ret[3] );
}
$text_color = ImageColorAllocate( $img1, $red, $green, $blue );
?>
chris at drunkenpirates dot co dot uk
14-Sep-2003 08:44
14-Sep-2003 08:44
<?php
/*
An example combining the use of ImageColorAllocate, Imagesetpixel, Imagecopyresized and some basic Trig
*/
Header("Content-type: image/png");
$height = 128;
$width = 128;
$imA = ImageCreate($width, $height);
$imB = ImageCreate($width*4, $height*4);
$bckA = ImageColorAllocate($imA, 0,0,0);
$bckB = ImageColorAllocate($imB, 0,0,0);
//GENERATE GRAY SCALE PALLETE
for($c=0;$c<256;$c++){
ImageColorAllocate($imA, $c, $c, $c);
}
//PRODUCE DATA
$m=rand(0,10);
for($c=0;$c<128;$c++){
$s= (sin( deg2rad($c*360*$m/128) )+1)*127;
$col_arr[$c]=$s;
}
for($y=0;$y<$height;$y++){
for($x=0;$x<$width;$x++){
$imgA[$x][$y]=$col_arr[$x];
}
}
for($y=0;$y<$height;$y++){
for($x=0;$x<$width;$x++){
$imgB[$x][$y]=$col_arr[$y];
}
}
//SET PIXELS
for($y=0;$y<$height;$y++){
for($x=0;$x<$width;$x++){
$imgC[$x][$y]=$imgA[$x][$y]+$imgB[$x][$y];
$s=$imgC[$x][$y]/2;
Imagesetpixel($imA,$x,$y,$s);
}
}
//RESIZE IMAGE FOR DISPLAY
Imagecopyresized ($imB, $imA, 0, 0, 0, 0, $width*4, $height*4, $width, $width);
ImagePNG($imB);
?>
leif at harmsen dot net
16-Apr-2003 10:31
16-Apr-2003 10:31
I was unable to get any of the posted methods for converting colour to grayscale to work. The problem appears to be the way gd creates images from jpeg inconsistently over various versions. Eventually I wrote my own that works for me - this approach allocates the 256 color pallete first. You can also play with separate $r, $g, $b variables before using imagecolorallocate in order to tone or tint the image.
<?php
$resource = 'whatever.jpg';
$im_size = GetImageSize($resource);
$imageWidth = $im_size[0];
$imageHeight = $im_size[1];
$im = imageCreate($imageWidth,$imageHeight);
for ($c = 0; $c < 256; $c++) {
ImageColorAllocate($im, $c,$c,$c);
}
$im2 = ImageCreateFromJpeg($resource);
ImageCopyMerge($im,$im2,0,0,0,0, $imageWidth, $imageHeight, 100);
ImageDestroy($im2);
?>
go on using $im as your image, it is now grayscale ....
jasper at pointless dot net
21-Jan-2003 09:20
21-Jan-2003 09:20
a patch to php 4.3.0 to add imagecolorallocatealpha is here:
http://pointless.net/~jasper/php-4.3.0-imagecolorallocatealpha.patch
cd php-4.3.0/ext/gd
patch < path/to/patch
and recompile and reinstall.
bisqwit at iki dot fi
17-Feb-2002 12:30
17-Feb-2002 12:30
Actually, you can't allocate more than 256 colours for an paletted image (ImageCreate).
Use ImageCreateTrueColor instead. For it to work, you need libgd version 2 support in php though.