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Digg  imagecolorallocate
Allocate a color for an image
(PHP 4, PHP 5)
Example 989. imagecolorallocate() example<?phpRelated Examples ( Source code ) » imagecolorallocate Examples ( Source code ) » Draw Filled Arc Examples ( Source code ) » Drawing a Circle Examples ( Source code ) » Drawing a Circle with imagearc() Examples ( Source code ) » Paint string value with different colors and position Examples ( Source code ) » Draw char with color Examples ( Source code ) » Draw string and fill rectangle Examples ( Source code ) » Using a Bounding Box to Center Text Examples ( Source code ) » Drawing a Square and a string Examples ( Source code ) » Draw Filled Ellipse Examples ( Source code ) » Draw ellipse Examples ( Source code ) » Filled ellipse Examples ( Source code ) » Set font Examples ( Source code ) » Create Color for paint Examples ( Source code ) » Color Examples ( Source code ) » Writing a String with imageTTFtext() Code Examples / Notes » imagecolorallocate18-jan-2005 10:23
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! ludo
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); ?> sw
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"); ?> aaron
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); ?> doiveo
This will help anyone trying to control font colors in a JPEG. You have to create a temporary image first, allocate the colors then merge the images before it works. Go figure. $im_size = GetImageSize ( "MySource.jpg" ); $imageWidth = $im_size[0]; $imageHeight = $im_size[1]; $im = imageCreate( $imageWidth, $imageHeight ); // - or with GD 2+ - // $im = imageCreateTrueColor( $imageWidth, $imageHeight ); // do all your color allocations here $font_color_black = ImageColorAllocate( $im, 0,0,0); $im2 = ImageCreateFromJPEG("MySource.jpg"); ImageCopy ($im,$im2,0,0,0,0, $imageWidth, $imageHeight); ImageDestroy ($im2); ...finish as you please using the $im var. mail
This nifty function will produce the negative of a given image! <?php /******************************** Code by Kailash Nadh http://kailashnadh.name usage: img2neg("my_pic.jpg"); *********************************/ function img2neg($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); } ?> jernberg
this might help someone, how to allocate an color from an html color-definition: $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, $blue ); lpespecial
This might help someone who want to use 'ImageColorAllocate ' with a hex value function ImageColorAllocateFromHex ($img, $hexstr) { $int = hexdec($hexstr); return ImageColorAllocate ($img, 0xFF & ($int >> 0x10), 0xFF & ($int >> 0x8), 0xFF & $int); } bob
The first color allocated will not fill the background if you use a true color image from imagecreatetruecolor().
smoli
Some of you maybe want to use HSV color model for drawing color selectors and circles: <? function &colormap_hsv_to_rgb($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; } ?> info
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. vassilis dourdounis
Regarding the problem people mention during the creation of gradients. Color allocation can only be done 255 times if your image is being created with imagecreate(). Use imagecreatetruecolor() if you want more colors. avi
quote from "tim at phantomrpg dot com" Here is a simpler way of using a hex color with ImageColorAllocate(). sscanf("FFFF00", "%2x%2x%2x", $red, $green, $blue); $stringColor=ImageColorAllocate($image,$red,$green,$blue); I made it into a simple function: <?php function fromhex($string){ GLOBAL $image; sscanf($string, "%2x%2x%2x", $red, $green, $blue); return ImageColorAllocate($image,$red,$green,$blue); } //Example for calling a hex color: ImageFill($image, 0, 0, fromhex('FFFFFF')); ?> william barath
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); ?> bisqwit
Looks like this function only allows allocating of 256 distinct colours. So this code: <?php $im = ImageCreate(500,200); for($a=0; $a<500; $a++) { $c = 128 + sin($a) * 127; ImageLine($im, $a,0, $a,199, ImageColorAllocate($im, $c,$c,$c)); } ob_start(); ImageJpeg($im, '', 75); $s = ob_get_contents(); ob_end_clean(); header('Content-type: image/jpeg'); header('Content-length: '.strlen($s)); print $s; will make an image that has changing colours at the first 256 pixel columns only. The rest are gray. miked
improvement upon fromhex function by avi at amarcus dot com <?php function fromhex($string,&$image) { sscanf($string, "%2x%2x%2x", $red, $green, $blue); return ImageColorAllocate($image,$red,$green,$blue); } //Example for calling a hex color: ImageFill($image, 0, 0, fromhex('FFFFFF')); ?> leif
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 $im as your image, it is now grayscale .... andreoli dot carlo
hsl to RGB (not yet optimized but it function) function hslToRgb ($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); } erik
Hi, During developing a gradient method I discovered that there can only be 255 colors allocated somehow... So the first 255 are going ok and after these the colorallocate function returns -1. My work around for this problem was to put the allocated color in an array and check if this variable exists before calling imagecolorallocate again. Did not had this problem again and my gradient scaled well after discovering this :) This is the piece of code that created a gradient PNG. The code is top down programmed and not put in a function or class yet. Because the code is 124 lines of code I've put the script at my website: http://beta.phpcastle.com/snippets/PHP/Image+Gradient (website still beta :P) I hope someone can use this addition marszysz
hex2color once again: this is the simplest possible method :) <?php $htmlcolor = "FF9900"; $color = hexdec ($htmlcolor); ?> Let's face the truth: for the truecolor images, imagecolorallocate doesn't allocate anything, but simply makes a hex representation of color, treats it as one large hex number, and calculates an int value from it. Oh, it's probably a good idea to validate $htmlcolor first, like: <?php if (!eregi('^[0-9a-f]{6}$', $htmlcolor)) die ("bad color"); ?> zigbigidorlu
Here's a very simple and very effective code to change a HEX color to RGB. ------------------------- function HEX2RGB($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); } ------------------------- carlosreche
Here is an easier way to set the color without use imagecolorallocate(); <?php $image = imagecreatetruecolor(); imagefill($image, 0, 0, 0xFFFFFF); // white color (#FFFFFF) ?> Use hexadecimal values just like you do in HTML codes: 0xFF0000 = red 0x00FF00 = green 0x0000FF = blue 0xFFFF00 = yellow ... and so on Hope this will help many people... Carlos Reche tim
Here is a simpler way of using a hex color with ImageColorAllocate(). sscanf("FFFF00", "%2x%2x%2x", $red, $green, $blue); $stringColor=ImageColorAllocate($image,$red,$green,$blue); Hope it helps someone. bruceb
Doiveo's suggestion for getting the font colors to behave with JPEG's does (at least for PHP 4.1.2 - GD version 1) stop the problem (that I had) with fonts becoming outlined instead of solid, however the font colors were still incorrect. There is however a much simpler (and faster) solution, just use imageColorClosest instead of imageColorAllocate, e.g: $near_white = imageColorClosest($img, 255,255,255); imageTTFtext($img, 10, 0, 20, 20, $near_white, "font file path", "text to add to JPEG"); For most JPEG's there should be a fairly close matching color to the one you want to use. timo dot witte
Do not use the hsv2rgb function from tyberis it calculates invalid output! There are 3 jumps in the resulting colorbar if you loop do a 0-360 for hue, saturation and value is calculated correctly.
picklecj
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. mlse
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. behun
Also, when you need more then 256 colors, use imagecreatetruecolor function. With this function you can use unlimited number of colors.
bisqwit
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. jasper
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. tyberis
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])); } } ?> chris
<?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); ?> mv
<? /** * 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); ?> |
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