Resolving Multisample Images
During the resolve the samples corresponding to each pixel location in the source are converted to a single sample before being written to the destination. If the source formats are floating-point or normalized types, the sample values for each pixel are resolved in an implementation-dependent manner. If the source formats are integer types, a single sample’s value is selected for each pixel.
Using a Resolve Attachment you can "downsample" an image. I assume this can be more efficient than issuing a vkCmdResolveImage
after the renderpass.