When setting up your online store, it is always advisable to specify a general image dimensions for your products which will dramatically help your buyers easily find the right product they are looking and make your product standout.
Just navigate to Catalog -> Preferences -> Item Tab -> Photos Section
This is a general preferences that handle all image upload in your store and automatically generate image dimensions base on the provided values. All uploaded product and category images are set to the default values specified in this area if you leave the option empty.
(1)You cannot resize a product image size higher than specified in the general preferences. If you have 500x500 default image dimension, you can only resize your image between 0 - 500 px. (2) All uploaded images are automatically resized base on the dimension specified in the general preferences upon upload. If you change the dimension in the general preferences after the images are uploaded, the changes won't take effect. It will affect only to new uploaded image. (3) Each product and category can be configured to display different images sizes. However you can only specify image dimensions within the minimum and maximum image dimension specified in general preferences.
You can specify the photo and downloadable file format, and maximum file size to keep your site organize.
Just navigate to Catalog -> Preferences -> Item Tab -> Photos and Media Section
You cannot set your downloadable max. size and photo max. size higher than your server max file upload. To increase your website maximum file upload, it needs to be done through your site php.ini.
