PHP内存不足更改内存大小没有帮助

我尝试用imagecopyresampled更改调整大小的图像。问题是我有非常大的图像，它是25000像素x 25000像素。我试着在本地主机上启动，我的电脑安装了8gb RAM。PHP我得到错误：

Fatal error: Out of memory (allocated 1844969472) (tried to allocate 86400 bytes)

我尝试在php.ini文件memory_limit=6144M和php文件ini_set('memory_limit', '-1');中增加内存大小，但这对没有帮助

me代码：

public function copyResample($pasteStartX, $pasteStartY, $startCopyX, $startCopyY, $dstWidth, $dstHeight, $srcWidth, $srcHeight, $outputPathToFileWOExt) {
    $dstImage = imagecreatetruecolor($dstWidth, $dstHeight);
    switch ($this->getMimeType()) {
        case 'image/jpg':
        case 'image/jpeg':
            $srcImage = imagecreatefromjpeg($this->getPathToFile());
            break;
        case 'image/png':
            $srcImage = imagecreatefrompng($this->getPathToFile());
            break;
        case 'image/gif':
            $srcImage = imagecreatefromgif($this->getPathToFile());
            break;
        default:
            throw new Exception("File is not an image, please use another file type.", 1);
    }
    imagecopyresampled($dstImage, $srcImage, $pasteStartX, $pasteStartY, $startCopyX, $startCopyY, $dstWidth, $dstHeight, $srcWidth, $srcHeight);
    switch ($this->getMimeType()) {
        case 'image/jpg':
        case 'image/jpeg':
            if (imagetypes() && IMG_JPG) {
                imagejpeg($dstImage, $outputPathToFileWOExt . "." . $this->getExt());
            }
            break;
        case 'image/png':
            if (imagetypes() && IMG_PNG) {
                imagepng($dstImage, $outputPathToFileWOExt . "." . $this->getExt());
            }
            break;
        case 'image/gif':
            if (imagetypes() && IMG_GIF) {
                imagegif($dstImage, $outputPathToFileWOExt . "." . $this->getExt());
            }
            break;
    }
}