Converting PNG to JPEG file

问题

I have a script to convert PNG files to JPEG files. Except, I'm not exactly sure how it works. What do use for $outputPngFile and $outputJpgFile? Can I do this with a tmp file, like when the user is uploading it? Then, how do I access the new file to move it to the proper image directory?

function pngTojpg($image, $outputPngFile, $outputJpgFile, $quality) {
$image = imagecreatefrompng($image);

//Save the png image
imagepng($image, $outputPngFile);         

//Save the jpeg image
imagejpeg($image, $outputJpgFile, $quality);

// Free up memory
imagedestroy($image);
}

回答1:

<?php
$image = imagecreatefrompng('yourlocation/image.png');
imagejpeg($image, 'yournewlocation/image.jpg', 70);
imagedestroy($image);
?>

回答2:

It would probably help you to know that you're using the GD library that has been bundled with PHP.

What the function is doing is taking a path to a png image ($image), loading it into a GD resource that can be manipulated within PHP (imagecreatefrompng), saving the image as a png to the png output path ($outputPngFile), then saving the image as a jpg to the jpg output path ($outputJpgFile) with a particular compression factor ($quality), and finally destroying the image resource object, since it isn't needed anymore.

Since it's saving the image as a png as well, the function was obviously intended to be used to save an image from either an external source (given by a URL) or temporary files from a user upload. You can do either, PHP doesn't care so long as the path you provide to the image file is valid.

来源：https://stackoverflow.com/questions/14220191/converting-png-to-jpeg-file

标签

php