Php Resizing image increase image size

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 (https://www.php.net/manual/en/image.constants.php look for PNG_FILTER_*).

See: https://www.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.