For many microstock agencies the minim is MP3-5. Alamy requires 48 MB in uncompressed version. This is not the file size of the jpg file. Depending on you program for resizing your image, it may tell you in the resize screen what the uncompressed size is. Usually the resolution ~5100 x ~3400 is ok to reach the 48 MB uncompresse size. Alamy will warn you when you are uploading the image and it is to small. You can start out with jpg files from your camera, but raw is probably better. Depending on your camera MP size you are ok with the upsizing or if you start out with a to small MP size then the images will become to soft of pixelated.
