Get image height and width of image stored on Amazon S3

Getting the file size is possible by reading the Content-Length response header to a simple HEAD request for your file. Maybe your client can help you with this query. More info on the S3 API docs.

Amazon S3 just provides you with storage, (almost) nothing more. Image dimensions are not accessible through the API. You have to get the whole file, and calculate its dimensions yourself. I'd advise you to store this information in the database when uploading the files to S3, if applicable.

You can store image dimensions in user-defined metadata when uploading your images and later read this data using REST API.

Refer to this page for more information about user-defined metadata: http://docs.aws.amazon.com/AmazonS3/latest/dev/UsingMetadata.html