It works now!
Before applying, I tried to look at
http://www.php.net/manual/en/function.fopen.php
Newbie advice: The little "b" for binary operations is very
essential when working with PHP4 and Apache on the win32 platform. fread()
only reads a couple of hundred bytes when reading for example an image
without "b".
// Read tempfile data into $thumb_img.
$thumb_file_size = filesize('C:\\Temp\\temp.jpg');
$fp = fopen('C:\\Temp\\temp.jpg', "rb");
$thumb_data = addslashes (fread ($fp, $thumb_file_size));
fclose ($fp);
unlink('C:\\Temp\\temp.jpg');
This case can be closed then, I hope it will help you to improve again your excellent application!