Php Resizing image increase image size - php

Question

I'm creating thumnails of uploaded file.
if image width and height are greater than 200 than then i re size them to 200px.
Here is code i used to do that:
if (file_exists($old_file)) {
$path_parts = pathinfo($old_file);
$extension = $path_parts['extension'];
$filename_path = $filepath . $filename;
$destination_path = $filename_path;
if (strtolower($extension) == "jpg" || strtolower($extension) == "jpeg") {
$uploadedfile = $old_file;
$src = imagecreatefromjpeg($uploadedfile);
} else if (strtolower($extension) == "png") {
$uploadedfile = $old_file;
$src = imagecreatefrompng($uploadedfile);
} else {
$uploadedfile = $old_file;
$src = imagecreatefromgif($uploadedfile);
}
list($width, $height) = getimagesize($uploadedfile);
$newwidth = $Size['width'];
$newheight = $Size['height'];
if ($width <= $newwidth && $height <= $newheight) {
$newwidth = $width;
$newheight = $height;
$tmp = imagecreatetruecolor($width, $height);
} else {
if ($width > $height) {
$newheight = ($height / $width) * $newwidth;
$tmp = imagecreatetruecolor($newwidth, $newheight);
} else {
$newwidth = ($width / $height) * $newheight;
$tmp = imagecreatetruecolor($newwidth, $newheight);
}
}
if ((strtolower($extension) == "png") OR (strtolower($extension) == "gif")) {
imagealphablending($tmp, false);
imagesavealpha($tmp, true);
$transparent = imagecolorallocatealpha($tmp, 255, 255, 255, 127);
imagefilledrectangle($tmp, 0, 0, $newwidth, $newheight, $transparent);
}
imagecopyresampled($tmp, $src, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
if (strtolower($extension) == "jpg" || strtolower($extension) == "jpeg") {
imagejpeg($tmp, $destination_path, 100);
} elseif (strtolower($extension) == "png") {
imagepng($tmp, $destination_path, 5);
} else {
imagegif($tmp, $destination_path);
}
chmod($destination_path, 0777);
imagedestroy($src);
imagedestroy($tmp);
ob_flush();
flush();
ob_end_flush();
return true;
} else {
return false;
}
it re size the large images to 200px by 200px but image size is increased in (byte and kb etc increased).
I tried uploading 8kb png file, and new thumbnail file size was 28kb?
Tried googling but didn't find anything helpful
Thanks.

Answer 1

Your source image is compressed, after parsing it you get a true color image, which is uncompressed. Then you save it with a compression level of 5 (in the case of PNG), which is pretty low compression, thus a higher filesize.
Try a higher compression, like 9, for example. Also try adding a combination of filters to decrease filesize (http://us3.php.net/manual/en/image.constants.php look for PNG_FILTER_*).
See: http://us3.php.net/manual/en/function.imagepng.php
http://en.wikipedia.org/wiki/Portable_Network_Graphics#Compression
http://en.wikipedia.org/wiki/Portable_Network_Graphics#File_size_factors
The GD library doesn't appear to provide any interfaces to let you in on low-level PNG data, but you can theoretically find out the source compression level and filters, by using other bindings or trying to read it manually.
http://www.libpng.org/pub/png/spec/1.2/PNG-Compression.html
http://www.libpng.org/pub/png/spec/1.2/PNG-Filters.html
The same may happen with JPG and GIF.