An image encoding device is provided that can transmit encoded image data without
lowering the frame rate even when the transmission speed of the transmission path
is lowered. An encoded region designator selects the region that is to be encoded,
in the input image, depending on the bit rate of the transmission path. Only such
a region that is designated by the encoded region designator is encoded. The encoded
region designator may be one which selects the region that is to be encoded, according
to the bit rate of the transmission path, and the motion vector detected by the
image encoding circuit. As an alternative, an encoded region designator may be
used which selects the region that is to be encoded according to the bit rate of
the transmission path, and the information on the designated region supplied from
the outside. Also, a selector limiting the number of bits of the signal from the
image signal input circuit may be provided, and when the bit rate of the transmission
path is lowered, the number of bits of the input image may be adaptively switched.
