JPS6419875A - Mh encoding circuit - Google Patents

Abstract

PURPOSE:To shorten an encoding time by equipping a detecting circuit to detect that all bits of one word of an image data signal are in the same color and an adding circuit to execute the adding of a continuous picture element number for every detection. CONSTITUTION:In a picture element number counting circuit 11, the image data signal is fetched from a data bus 1 to a register 2 for every word, next, moved to a shift register 2 and after that, a run length is counted by a counter 5 while it is shifting for every bit. In a white black and black white changing point detecting circuit 4, when a change from white to black or from black to white is detected, the code of a value shown by the counter 5 is immediately indexed from a code table 6 and the code is outputted to an output 9. On the other hand, when image data are fetched to the register 2 and the one word is detected to be all white or all black by an all white and all black detecting circuit 7, 16 is added to the value of the counter by an adding circuit 8. In such a case, the data are not moved to the shift register 3.