Image Resolutions

Images are 2 dimensional, X * Y.

If image contains the whole earth, ie, full 360° x 180° and is WGS84 (aka EPSG:4326) projection then

Size Minutes latitude, and longitude at the equator
360x180 1 pixel per 60 minutes(1°)
720x360 1 pixel per 30 minutes latitude
1440x720 1 pixel per 15 minutes latitude
2880x1440 1 pixel per 7.5 minutes latitude
5400x2700 1 pixel per 4 minutes latitude
10800x5400 1 pixel per 2 minutes latitude
21600x10800 1 pixel per 1 minutes latitude
86400x43200 1 pixel per 1/4 minutes (15 Seconds) latitude
1296000x648000 1 pixel per 1/60 minutes(1 Second) latitude

1 minute of latitude, and longitude at the equator, is 1 nautical mile.

1 Nautical Mile = 1 minute = 60 seconds,

1 second = 1/60 Nautical Mile = 0.0191796575 Miles = 0.03086666…KM = 30.8666666…meters