Resolution
the level of detail of an image
the level of detail of an image
The RGB colour model utilizes the additive model in which red, green, and blue light are combined in various ways to create other colours. The very idea for the model itself and the abbreviation "RGB" come from the three primary colours in additive light models.
To help you get your bearings, you can choose to display Rulers. [View --> Rulers] Rulers appear along the top and the left side of the Stage.The ruler is measured in pixels. 