Abstract: A display system for converting first gray level signals of N bits/dot each, representing 2.sup.N gray levels, to second gray level signals of M bits/dot each, representing 2.sup.M gray levels, where N is an integer larger than or equal to 2 and M is an integer satisfying N>M.gtoreq.1, by separating each of the first gray level signals of N bits into higher M bits and lower N-M bits and respectively using the N-M bit values to select an appropriate table from among 2.sup.N-M tables, each of which stores a distinctive set of P.times.Q modification values satisfying P.times.Q.gtoreq.2.sup.N-M, then respectively adding the M bits and each of the modification values of said selected table to generate P.times.Q second gray level signals, and supplying the resulting second gray level signals to a display device of 2.sup.M gray levels. The first gray level signals may be supplied to a display device of 2.sup.N gray levels having a smaller number of display dots than the display device of 2.sup.M gray levels.

Abstract: A heat exchanger for lowering the temperature of exhaust gas emitted from an internal combustion engine has a container body adapted to store water which serves a heat exchanging medium therein, an exhaust gas discharging chamber adapted to discharge the exhaust gas from the engine into the water in the form of gas-bubbles, a partition member mounted above the surface of water stored within said container body so as to catch splash of water, water-bubbles and vapor generated by evaporation of water and drop them within the container body; an exhaust gas inlet formed in the peripheral side surface of the container body and connected to exhaust pipe for the engine; an exhaust gas introduction passage for connecting the exhaust gas inlet and the exhaust gas discharging chamber; an exhaust gas exit chamber defined in the uppermost part of the inside of the container body; and an exhaust gas outlet pipe connected to the top of said container body to discharge the exhaust gas within the exhaust gas discharge chambe