In order to reduce aliasing as much as possible in a display apparatus
that has a delta arrangement type screen, an image filter for performing
a neighborhood operation is incorporated as a previous stage of a screen
driving circuit. The image filter realizes low pass filtering including
space frequency limitation in the diagonal direction that is suitable for
a display on the delta arrangement type screen. Coefficients that
constitute the filter matrix are optimized so that frequency components
that exceed a Nyquist limit in the delta arrangement are suppressed.
Coefficients that give optimal filter characteristics for any scale of
filter matrix are defined by an expression.