[edit] Last updated: Fri, 25 May 2012

imagecolorset

(PHP 4, PHP 5)

imagecolorset — 指定したパレットインデックスの色を設定する

説明

void imagecolorset ( resource $image , int $index , int $red , int $green , int $blue [, int $alpha = 0 ] )

この関数は、パレット上で指定したインデックス index を指定した色 color に設定します。実際にぬりつぶしを実行するオーバーヘッドなしにパレット上の色を使用する画像をぬりつぶしたような効果を得ることができ、便利です。

パラメータ

image: imagecreatetruecolor() のような画像作成関数が返す画像リソース。
index: パレットのインデックス。
red: 赤コンポーネントの値。
green: 緑コンポーネントの値。
blue: 青コンポーネントの値。
alpha: アルファコンポーネントの値。

返り値

値を返しません。

変更履歴

バージョン	説明
5.4.0	`alpha` パラメータが追加されました。

例

例1 imagecolorset() の例


<?php
// 300x100 の画像を作成します
$im = imagecreate(300, 100);

// 背景色を赤に設定します
imagecolorallocate($im, 255, 0, 0);

// 背景の色インデックスを取得します
$bg = imagecolorat($im, 0, 0);

// 背景色を青に設定します
imagecolorset($im, $bg, 0, 0, 255);

// 画像をブラウザに出力します
header('Content-Type: image/png');

imagepng($im);
imagedestroy($im);
?>

参考

imagecolorat() - ピクセルの色のインデックスを取得する

imagecolorsforindex

imagecolorresolvealpha

[edit] Last updated: Fri, 25 May 2012

add a note User Contributed Notes imagecolorset

Bartman 25-Aug-2009 11:12


I had the same problem as heavyraptor2 so i made this function...

<?php

function imagecolorize($im,$endcolor){

    //funcion takes image and turns black into $endcolor, white to white and

    //everything in between in corresponding gradient

    //$endcolor should be 6 char html color



    //make sure it has usable palette

    if (imageistruecolor($im)) {

        imagetruecolortopalette($im, false, 256);

    }



    //first make it gray to be sure of even results (thanks moxleystratton.com)

    //comment this loop if you want the output based on, for example, 

    //the red channel (for this take a look at the $gray-var in the last loop)

    for ($c = 0; $c < imagecolorstotal($im); $c++) {

        $col = imagecolorsforindex($im, $c);

        $gray = round(0.299 * $col['red'] + 0.587 * $col['green'] + 0.114 * $col['blue']);

        imagecolorset($im, $c, $gray, $gray, $gray);

    }



    //determine end-colors in hexdec

    $EndcolorRGB['r'] = hexdec( substr($endcolor, 0, 2));

    $EndcolorRGB['g'] = hexdec( substr($endcolor, 2, 2));

    $EndcolorRGB['b'] = hexdec( substr($endcolor, 4, 2));



    //determine gradient-delta's

    $stepR = (255-$EndcolorRGB['r'])/255.0;

    $stepG = (255-$EndcolorRGB['g'])/255.0;

    $stepB = (255-$EndcolorRGB['b'])/255.0;



    //aColor contains the 256 gradations between endcolor(i=0) and white(i=255)

    $aColor = array();

    for ($i = 0; $i<=255; $i++){

        $aColor[$i]['r'] = $EndcolorRGB['r'] + ($i*$stepR);

        $aColor[$i]['g'] = $EndcolorRGB['g'] + ($i*$stepG);

        $aColor[$i]['b'] = $EndcolorRGB['b'] + ($i*$stepB);

    }



    //for every color-index we now replace $gray-values for $aColor

    for ($c = 0; $c < imagecolorstotal($im); $c++){

        $currentColorRGB = imagecolorsforindex($im, $c);

        $gray = $currentColorRGB['red'];//image is grayscale, so red,green and blue

        // should be equal. We use this number as key of aColor

        imagecolorset($im,$c,(int)$aColor[$gray]['r'], (int)$aColor[$gray]['g'], (int)$aColor[$gray]['b']);

    }

}?>

Thomas Mueller 23-Apr-2008 07:42


Here is a function to colorize a picture gradient style.



All you have to do is to pass an img-object and an array of colors.



e.g.



$arr = array('#000000', '#990000', '#00FFFF', '#FFFFDD');

colorize ($img, $arr);



<?php

function colorize($imgdata, $palette)

{

    imageTrueColorToPalette($imgdata,false,0xFF);

    $l = count($palette)-1;

    $i = imagecolorstotal($imgdata);

    while ($i--)

    {

        list($r,$g,$b) = array_values(imageColorsForIndex($imgdata,$i));

        

        $grayscale = ($r*.3 + $g*.59 +$b*.11) / 0xFF;

        

        $pos = $l*$grayscale;

        

        $perc = $pos-floor($pos);

        

        $tbase = str_replace("#", '', $palette[$pos]);

        $baseR = hexdec(substr($tbase,0,2));

        $baseG = hexdec(substr($tbase,2,2));

        $baseB = hexdec(substr($tbase,4,2));

        

        $tmix = str_replace("#", '', $palette[$pos+1]);

        $mixR = hexdec(substr($tmix,0,2));

        $mixG = hexdec(substr($tmix,2,2));

        $mixB = hexdec(substr($tmix,4,2));

        

        $resR = $baseR+($mixR-$baseR)*$perc;

        $resG = $baseG+($mixG-$baseG)*$perc;

        $resB = $baseB+($mixB-$baseB)*$perc;

        

        imagecolorset($imgdata, $i, $resR, $resG, $resB);

    }

}

?>

heavyraptor2 at hotmail dot com 20-Feb-2008 10:08


I've been looking for a simple function which "colorizes" an image, without any success ... it looks like a lot of people mean something different with "colorizing" an image, because actually colorzing means multiplying the old color's grayscale with the new color. So a white pixel would become 100% of the colorize-to-color and a black pixel would stay black (I know I can't explain well ... I hope you understood, otherwise take a look at the example below the functions' code).



<?php

function image_colorize(&$img,$rgb) {

  imageTrueColorToPalette($img,true,256);

  $numColors = imageColorsTotal($img);



  for ($x = 0; $x < $numColors; $x++) {

    list($r,$g,$b) = array_values(imageColorsForIndex($img,$x));



    // calculate grayscale in percent

    $grayscale = ($r + $g + $b) / 3 / 0xff;



    imageColorSet($img,$x,

      $grayscale * $rgb[0],

      $grayscale * $rgb[1],

      $grayscale * $rgb[2]

    );

  }



  return true;

}

?>



Example of usage:

<?php

$color = array(0xff,0xaa,0x2a); // color to convert to

$url = 'http://sundog.net/images/uploads/1_google_logo.jpg';

$img = imageCreateFromJpeg($url);



image_colorize($img,$color);



header('Content-type: image/gif');

imageGif($img);

exit;

?>



Enjoy

admin at phpgfx dot com 25-Aug-2007 08:37


Here is a function to turn an image into pure black and white



<?php



function imagepurebw( $img, $amount = 383 ) {

    $total = imagecolorstotal( $img );

    for ( $i = 0; $i < $total; $i++ ) {

        $index = imagecolorsforindex( $img, $i );

        array_pop( $index );

        $color = ( array_sum( $index ) > $amount ) ? 255 : 0;

        imagecolorset( $img, $i, $color, $color, $color );

    }

}



?>

moxleystratton.com 05-Oct-2006 12:59


If you want to convert a Color image to Grayscale without creating a blotchy image, use this color calculation:

<?php

function imagetograyscale($im)

{

    if (imageistruecolor($im)) {

        imagetruecolortopalette($im, false, 256);

    }



    for ($c = 0; $c < imagecolorstotal($im); $c++) {

        $col = imagecolorsforindex($im, $c);

        $gray = round(0.299 * $col['red'] + 0.587 * $col['green'] + 0.114 * $col['blue']);

        imagecolorset($im, $c, $gray, $gray, $gray);

    }

}

?>

dade dot c at email dot it 02-Oct-2004 10:47


this is helpful if you would like to implement a color theme system in your website... try it out

Davide Candiloro Italy



function colorize ($pngpath, $r, $g, $b) 

/*

REQUIRES: $pngpath to be a valid path of a greyscale PNG-8 image with 64 colors palette

          $r, $g, $b to be integers in the range 0..255

EFFECTS: returns the png image colorized with the color represented by $r, $g, $b.

*/

{

    header("Content-type: image/png");

    $im = imagecreatefrompng("images/table.png");



    imagetruecolortopalette($im, FALSE, 256); 

   

      for ($c = 0; $c < 64; $c++){ /*64 is the number of colors in the PNG-8 palette*/

        $col = imagecolorsforindex($im, $c);           

        imagecolorset ( $im, $c, $r*$col['red']/256, $g*$col['green']/256, $b*$col['blue']/256); /*replaces original greyscale palette with a colorized one*/

     }



    imagepng($im);

    imagedestroy($im);

}

m4551 at abasoft dot it 23-Apr-2004 06:19


here's a function to greyscale an image even from a truecolor source (jpeg or png).



slightly poor quality, but very fast...



function imagegreyscale(&$img, $dither=1) {    

    if (!($t = imagecolorstotal($img))) {

        $t = 256;

        imagetruecolortopalette($img, $dither, $t);    

    }

    for ($c = 0; $c < $t; $c++) {    

        $col = imagecolorsforindex($img, $c);

        $min = min($col['red'],$col['green'],$col['blue']);

        $max = max($col['red'],$col['green'],$col['blue']);

        $i = ($max+$min)/2;

        imagecolorset($img, $c, $i, $i, $i);

    }

}

info at devking dot com 08-Aug-2002 11:20


here's a simple function to greyscale an image...



function imagecolorgrey( &$img ) {

 for( $i=0; $i<imagecolorstotal( $img ); $i++ ) {

  $c = ImageColorsForIndex( $img, $i );

  $t = ($c["red"]+$c["green"]+$c["blue"])/3;

  imagecolorset( $img, $i, $t, $t, $t );    

 }

}

olivier at moostik dot net 12-Jul-2001 02:49


This function change colors of an image with ranges 0>100 for each primary color:





int ImageSelectiveColor (int im, int red, int green, int blue)





im is image pointer


red, green and blue are ranges 0->100





function ImageSelectiveColor($im,$red,$green,$blue)


 {


  for($i=0;$i<imagecolorstotal($im);$i++)


   {


    $col=ImageColorsForIndex($im,$i);


    $red_set=$red/100*$col['red'];


    $green_set=$green/100*$col['green'];


    $blue_set=$blue/100*$col['blue'];


    if($red_set>255)$red_set=255;


    if($green_set>255)$green_set=255;


    if($blue_set>255)$blue_set=255;


    imagecolorset($im,$i,$red_set,$green_set,$blue_set);


    


   }


  return $im;


 


 }

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