S3 post operations will store the image into a configured AWS S3 bucket. To achieve that, the S3 credentials (access key id, and secret access key) are needed in addition to an already created bucket. Optionally, you can configure a path inside the bucket and also the object metadata that will be sent with the image (besides the Content-Type which will be of the image type). It is recommended to create a separate credential pairs just for imager200 with access to the bucket only. If you are planning to add the ACL (e.g public-read, private…) to the object metadata (x-amz-acl), the credentials user need to have PutObjectAcl permission, otherwise the post operation will fail.