All regions inside specified areas of interest are called “foreground”. All surrounding regions are called “background”. The Inner and Outer radio buttons correspond respectively to foreground and background and enable you to choose which part of an image the AOI processing will affect.
In MrSID encoding, “inner” and “outer” are not specifically referred to except when using the mask method, as noted below. Either the foreground or background is given preference by the difference in weight between them as specified by the compression ratio of the foreground and that of the area(s) of interest.
In JP2 encoding using the weight and shift methods, selecting the “Weight Inner” or the “Shift Inner” button preserves the quality of the foreground at the expense of the surrounding regions. Similarly, selecting “Weight Outer” or “Shift Outer” preserves the quality of the background at the expense of the foreground.
The mask method renders either the foreground (by selecting the Inner check box) or background (by selecting the Outer check box) as a solid color.