After a few months of testing image optimization solutions by TinyPNG and ImageMagick I have found that actually, there is another way of storing images in Kentico that has not been covered yet: Product Images. If you open the Products application, go to any product and look at the Image field, guess where and how this image is stored?
The correct answer would be - this is a Meta File (check out CMS_MetaFile table in the database), and neither a Media File or a Page Attachment. Meta Files are classified as Object Attachments. And they require a separate route of processing. You can find it supported in the updated vesions of these Nuget packages:
Just run the Nuget package update command, rebuild your projects and run - as simple as that!
Update-Package DeleteAgency.Kentico12.TinyPng -- or -- Update-Package DeleteAgency.Kentico12.ImageMagick
Kentico 11 support
Keeping it short for today, these image optimization packages are now also available for Kentico 11:
Install-Package DeleteAgency.Kentico11.TinyPng -- or -- Install-Package DeleteAgency.Kentico11.ImageMagick
Optimized images and happy coding to all of you!