Image Upload Quality

[geogal]

Hi all,

I have a script that works wonderfully with uploading an image, resizing it, placing it into a file and calling it out from a database. This has worked for several months.

Now I'm getting bad image quality when I upload that I've never seen before. All of my photos are coming out blue. This sounds stupid, but I didn't touch my script and I can't figure out why the quality is sometimes good and sometimes bad (it's not constant). The files I'm uploading are regular .JPG files, which the script converts to .PNGs.

Here is the script that processes the upload:

<?

If ($btnMain){

$date = date("gismdY");
$rand = rand(1,20);

list(,$type) = split("\.",$_FILES['userfile']['name'],2);

switch($type)
{
    case "jpg":
         $oldImage=imageCreateFromJPEG($_FILES['userfile']['tmp_name']);
        break;
    default:
        die('Unsupported image type. Please upload .jpg files only.');
}

$image = $oldImage;
$width = imagesx($image);
$height = imagesy($image);

if ($width > 150)
{
$new_width = 150;
$new_height = ($new_width * $height) / $width;
}
else
{
$new_width = $width;
$new_height = $height;
}

$newImage = imagecreate($new_width,$new_height);

imagecopyresized($newImage,$image,0,0,0,0,$new_width,$new_height,$width,$height);

imagePNG($newImage,"../../images/inventory/$date.$rand.png");

move_uploaded_file($_FILES['userfile']['tmp_name'],"../../images/inventory/$date.$rand.$png");
imagedestroy($image);
imagedestroy($newImage);

$query = "UPDATE inventory SET image='../../images/inventory/$date.$rand.png' WHERE ID = $iID";
$result = mysql_query($query);
move_uploaded_file($FileToUpload, "../../images/inventory/$date.$rand.png");

?>

Like I said, the actual process works, but the images are terrible. I noticed while looking at the PNGs that they are being converted to Index Color. Can this be the problem?

Thanks for any help.

Geogal

[jopie916]

I looked up imagecopyresized() in my php manual, it says:

Note: There is a problem due to palette image limitations (255+1 colors). Resampling or filtering an image commonly needs more colors than 255, a kind of approximation is used to calculate the new resampled pixel and its color. With a palette image we try to allocate a new color, if that failed, we choose the closest (in theory) computed color. This is not always the closest visual color. That may produce a weird result, like blank (or visually blank) images. To skip this problem, please use a truecolor image as a destination image, such as one created by imagecreatetruecolor().

I hope that's helpful, I noticed you're not using "imagecreatetruecolor()" in your code.

If that dosen't work, my first guess would be something like a altered or corrupted color pallette, if that's possible (I really don't know much about that).

[Weedpacket]

Yes, I recall this happening to me, now; after upgrading from GDLib 1.x to version 2, all those truecolour->indexed conversions turned to custard. Using the truecolour functions worked.

I guess there's no desire on GDLib's authors to address this, as the only file format worth mentioning that doesn't support truecolour images is a format that GDLib doesn't support anyway. (Which would be why the quality of the colour mapping has degraded.)

[geogal]

Thanks, both of you, for the feedback! Jopie916, the imageTrueColor worked like a charm. My hosting company must have upgraded the GDlib recently, because I hadn't had this problem until now.

Thanks again, from me and my company's client!

Geogal