Convert JPG/GIF image to PNG in PHP?

Question

Possible Duplicate of
Convert jpg image to gif, png & bmp format using PHP

I have a PHP form that allows image uploads and checks exif_imagetype(); to make sure an image is valid.

However, I want all formats, PNG, JPG, JPEG, and GIF, to end up being PNG once submitted.

How can I go about doing this?

Answer 1

You just need imagepng() then. In fact it almost becomes a one-liner:

 imagepng(imagecreatefromstring(file_get_contents($filename)), "output.png"); 

You would use $_FILES["id"]["tmp_name"] for the filename, and a different output filename obviously. But the image format probing itself would become redundant.

Answer 2

Based on what kind of image it is you could select the correct function to open the file:

$extension = strtolower(pathinfo($filename, PATHINFO_EXTENSION));  switch ($extension) {     case 'jpg':     case 'jpeg':        $image = imagecreatefromjpeg($filename);     break;     case 'gif':        $image = imagecreatefromgif($filename);     break;     case 'png':        $image = imagecreatefrompng($filename);     break; } 

Then you just save the file using:

imagepng($image, $new_filename, $quality); 

It might be worth noting that this will only parse the actual extension and not really validate so the file is in the specific format. For instance, you could take a jpg image and just change the extension to png. So a better approach is to use the exif_imagetype() which will return the type of image not depending on the actual extension.

Answer 3

<form method="post" enctype="multipart/form-data">
<input type="file" name="image" />
<input type="submit" name="submit" value="Submit" />
</form>

<?php
if(isset($_POST['submit']))
{
    if(exif_imagetype($_FILES['image']['tmp_name']) ==  IMAGETYPE_GIF) 
    {
        $newpng = 'image.png';
        $png = imagepng(imagecreatefromgif($_FILES['image']['tmp_name']), $newpng);
    }
    elseif(exif_imagetype($_FILES['image']['tmp_name']) ==  IMAGETYPE_JPEG) 
    {
        $newpng = 'image.png';
        $png = imagepng(imagecreatefromjpeg($_FILES['image']['tmp_name']), $newpng);
    }
    else //already png
    {
        $newpng = 'image.png';
    }       
}
?>