Features:

• Reduce image file size (according with image quality level defined in settings)
• Smaller image file size = increase website speed
• Quality levels accepted (between 0 and 100)
• No external services required (extension use GD Library)
• No files overwrited VQMOD used (OC 1.5.x) and  modification system for OC 2.0.x
• Quality level 0: worst image quality, smallest file size
• Quality level 100: best image quality, biggest file size 
• Default Opencart Quality level is 90.