It seems that WordPress Media Library is compressing uploaded jpeg images by default to 90% of their original quality.. While this is done order to save your hosting bandwidth sometimes it doesn't work that good especially if your website is oriented to selling or re-selling images .. Navigate to 'Add New in the plugins dashboard. Search for 'Disable JPEG Image Compression. Activate the plugin on the Plugin dashboard... Disable JPEG Image Compression is open software. The following people have contributed to this plugin... Interested in development.., check out SVN repository, or subscribe to the development log by RSS...
Read more