PHP imagefilter and uploadify - php

Question

I have a question on how to filter image while moving the file. I used uploadify to upload image. What I did is, before he move the image to the directory, the code filter will covert the image to grayscale.
Here is my code
if (!empty($_FILES)) {
$tempFile = $_FILES['Filedata']['tmp_name'];
$targetPath = $_SERVER['DOCUMENT_ROOT'] . $_REQUEST['folder'] . '/';
$targetFile = str_replace('//','/',$targetPath) . $_FILES['Filedata']['name'];
$newImg = imagefilter($tempFile, IMG_FILTER_GRAYSCALE); // This is what I insert
move_uploaded_file($newImg,$targetFile);
echo "1";
}
The code is uploadify.php and I just inserted a filter to make it grayscale. Please help me. Thanks in advance.

Answer 1

Imagefilter works on an image resource, not a file, and also a boolean, not a new image. It's probably worth reading through the documentation, but you'll need to change your code to something along these lines
if (!empty($_FILES)) {
$tempFile = $_FILES['Filedata']['tmp_name'];
$targetPath = $_SERVER['DOCUMENT_ROOT'] . $_REQUEST['folder'] . '/';
$targetFile = str_replace('//','/',$targetPath) . $_FILES['Filedata']['name'];
// Create an image resource - exact method will depend on the image type (PNG, JPEG, etc)
$im = imagecreatefrompng($tempFile);
// Apply your filter
imagefilter($im, IMG_FILTER_GRAYSCALE);
// Save your changes
imagepng($im, $tempFile);
move_uploaded_file($tempFile,$targetFile);
echo "1";
}

Answer 2

To use imagefilter you have to load image first. Use one of GD load functions ( like: imagecreatefrompng).
Then you can use filter on loaded image. By the way check parameters for imagefilter (which requires loaded image, not path to image). Here is some example code (that replaces your imagefilter()):
// Check extension of the file, here is example if the file is png, but you have to check for extension and use specified function
$img = imagecreatefrompng($tempFile);
if( imagefilter($img, IMG_FILTER_GRAYSCALE) )
{
// success
}
else
{
// failture
}
// Save file as png to $targetFile
imagepng($img, $targetFile);
// Destroy useless resource
imagedestroy($img);