[FIXED] Why do images saved to file differ in size from resources with imagejpeg()?

Issue

I'm generating thumbnails from images automatically with the PHP GD library.
I then save the resized image to a file using imagejpeg() with 95% quality.

When I output this file using echo file_get_contents($file), the filesize of the image is always about 2.5 - 4 times as large compared to when I directly output the resized image to the browser using imagejpeg($resource_handle).

Google PageSpeed also tells me images could be compressed by 75%, which confirms the 1/4 ratio noticed.

What could be the reason for this?

Solution

I found the manual (http://php.net/manual/en/function.imagejpeg.php) mentions that the default (without passing the quality argument) quality setting is around 75%.

This explains why outputting an image directly without any other arguments passed to imagejpeg() results in a smaller image then when setting a quality higher than 75 manually.

Answered By - Bastiaan ten Klooster

Answer Checked By - Willingham (PHPFixing Volunteer)