imagepalettetotruecolor

(PHP 5 >= 5.5.0, PHP 7, PHP 8)

imagepalettetotruecolor — Converts a palette based image to true color

说明

imagepalettetotruecolor ( GdImage $image ) : bool

Converts a palette based image, created by functions like imagecreate() to a true color image, like imagecreatetruecolor().

参数

image: 由图象创建函数(例如imagecreatetruecolor())返回的图象资源。

返回值

Returns true if the convertion was complete, or if the source image already is a true color image, otherwise false is returned.

更新日志

版本	说明
8.0.0	`image` expects a GdImage instance now; previously, a resource was expected.

范例

Example #1 Converts any image object to true color


<?php
// Backwards compatiblity
if(!function_exists('imagepalettetotruecolor'))
{
    function imagepalettetotruecolor(&$src)
    {
        if(imageistruecolor($src))
        {
            return(true);
        }

        $dst = imagecreatetruecolor(imagesx($src), imagesy($src));

        imagecopy($dst, $src, 0, 0, 0, 0, imagesx($src), imagesy($src));
        imagedestroy($src);

        $src = $dst;

        return(true);
    }
}

// Helper closure
$typeof = function() use($im)
{
    echo 'typeof($im) = ' . (imageistruecolor($im) ? 'true color' : 'palette'), PHP_EOL;
};

// Create a palette based image
$im = imagecreate(100, 100);
$typeof();

// Convert it to true color
imagepalettetotruecolor($im);
$typeof();

// Free the memory
imagedestroy($im);
?>

以上例程会输出：

typeof($im) = palette
typeof($im) = true color

参见

imagecreatetruecolor() - 新建一个真彩色图像
imageistruecolor() - 检查图像是否为真彩色图像

User Contributed Notes

walf - iftfy 17-Mar-2017 03:46


here the working version of walf's solution



<?php

// Backwards compatiblity

if (!function_exists('imagepalettetotruecolor')) {

    function imagepalettetotruecolor(&$src) {

        if (imageistruecolor($src)) {

            return true;

        }



        $dst = imagecreatetruecolor(imagesx($src), imagesy($src));

     

        imagealphablending($dst, false);//prevent blending with default black

        $transparent = imagecolorallocatealpha($dst, 255, 255, 255, 127);//change the RGB values if you need, but leave alpha at 127

        imagefilledrectangle($dst, 0, 0, imagesx($src), imagesy($src), $transparent);//simpler than flood fill

        imagealphablending($dst, true);//restore default blending



        imagecopy($dst, $src, 0, 0, 0, 0, imagesx($src), imagesy($src));

        imagedestroy($src);



        $src = $dst;

        return true;

    }

}

?>

Polda18 30-Apr-2014 02:44


PHP ver 5.4.24 does not support this function (it has not been defined). To get rid of this, you must copy image resource to new image created by function imagecreatetruecolor();



Example with image loaded from GIF file:



$image  = imagecreatefromgif("path/to/gif/file.gif");  //create an image from GIF

$width  = imagesx($image);                             //get width of source image

$height = imagesy($image);                             //get height of source image

$image2 = imagecreatetruecolor($width,$height);        //create new image of true colors with given width and height

imagecopy($image2,$image,0,0,0,0,$width,$height);      //copy source image to new one



header("Content-Type: image/jpeg");                    //set header for JPG image

imagejpg($image2);                                     //render JPg image into browser



imagedestroy($image);                                  //free up memory

imagedestroy($image2);

walf 21-Mar-2014 06:20


The backwards compatibility example does not preserve transparency. You must first wipe out the default black background on the new image:



<?php

// Backwards compatiblity

if (!function_exists('imagepalettetotruecolor')) {

    function imagepalettetotruecolor(&$src) {

        if (imageistruecolor($src)) {

            return true;

        }



        $dst = imagecreatetruecolor(imagesx($src), imagesy($src));

        

        imagealphablending($dst, false);//prevent blending with default black

        $transparent = imagecolorallocatealpha($new_image, 255, 255, 255, 127);//change the RGB values if you need, but leave alpha at 127

        imagefilledrectangle($dst, 0, 0, $imagesx($src), imagesy($src), $transparent);//simpler than flood fill

        imagealphablending($dst, true);//restore default blending



        imagecopy($dst, $src, 0, 0, 0, 0, imagesx($src), imagesy($src));

        imagedestroy($src);



        $src = $dst;

        return true;

    }

}

?>