imagecolorset()

(PHP 4, PHP 5, PHP 7)

给指定调色板索引设定颜色

说明

本函数将调色板中指定的索引设定为指定的颜色。对于在调色板图像中创建类似区域填充（flood-fill）的效果很有用，免去了真的去填充的开销。

参见imagecolorat()。

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 
If you want to convert a Color image to Grayscale without creating a blotchy image, use this color calculation: 
If you are creating a palette image from scratch you have to use imagecolorallocate() for each index before you can use imagecolorset() on it.
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); 
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).

Example of usage:

Enjoy
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; $c 
This function change colors of an image with ranges 0>100 for each primary color:
int ImageSelectiveColor (int im, int red, int green, int blue)
im is image pointer
red, green and blue are ranges 0->100
function ImageSelectiveColor($im,$red,$green,$blue)
 {
 for($i=0;$i255)$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;
 
 }
I had the same problem as heavyraptor2 so i made this function...

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