black watermark

[ricmetal]

hi guys

i need some help

i am trying to create a resized image with a watermark, from an uploaded image..

the image is getting uploaded and resized but the watermark doesnt appear correct.

instead of a transparent watermark, there's a black square in it's place.

this is my code

$tempfile = $_FILES['filename']['tmp_name'];
$src = imagecreatefromjpeg($tempfile);
list($origWidth, $origHeight) = getimagesize($tempfile);
// creating png image of watermark
$watermark = imagecreatefrompng('../imgs/watermark.png');
// getting dimensions of watermark image
$watermark_width = imagesx($watermark);
$watermark_height = imagesy($watermark);
// placing the watermark
$dest_x = $origWidth / 2 - $watermark_width / 2;
$dest_y = $origHeight / 2 - $watermark_height / 2;
imagecopyresampled($src, $watermark, $dest_x, $dest_y, 0, 0, $watermark_width, $watermark_height, $origWidth, $origHeight);
imagealphablending($src, true);
imagealphablending($watermark, true);
imagejpeg($src,$galleryPhotoLocation,100); // $galleryPhotoLocation is correct. the image gets uploaded successfully..

 

 

[ricmetal]

so i managed to get the script working with imagecopy, instead of imagecopyresampled.

but i don't understand the difference between the two. could anyone explain? thanks

[Psycho]

so i managed to get the script working with imagecopy, instead of imagecopyresampled.

but i don't understand the difference between the two. could anyone explain? thanks

 

Have you tried reading the manual for those two functions?

http://php.net/manual/en/function.imagecopyresampled.php

http://us3.php.net/manual/en/function.imagecopy.php

 

And I don't mean just skimming the description. Typically, if there are certain issues that can be encountered with a function the information is there if you take the time to read it. Specifically, I see this in the manual page for imagecopyresampled()

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 don't know if that is the cause of the problem you experienced, but it definitely sounds like a possibility.

[ricmetal]

thanks damato

that's probably it.

i should read the manual in more detail!