Image processing apparatus which provides an indication of whether an odd or an even field is displayed

An image display system comprising:

• a plurality of registers, each for storing predetermined data;
• a CPU (central processing unit);
• internal devices, each performing a different task;
• means for counting dot clock signals and horizontal synchronizing signals;
• means responsive to the counting means for detecting whether odd or even fields of the image are being displayed, whether a display period or a fly-back period is in process, and which raster number in a horizontal display period is being displayed;
• means for supplying the data detected by the detecting means to at least one of said registers;
• wherein the CPU monitors a current condition of a displayed image and controls the internal devices at exact timings given in accordance with the data stored in said registers;
• and
• means for selectively displaying an image in one of a plurality of display modes, said modes comprising a non-interlace mode, a general interlace mode, and an interlace mode with a 1/2 dot shift.