Imaging system with two level dithering using comparator

An apparatus for translating input levels of an imaging system to corresponding output levels, said apparatus comprising:

• Look Up Table (LUT) generator means for generating dither template values for the input levels of an imaging system, which has an input device which is able to represent any number of input levels provided that number is equal to or greater than two, and which has an output device in which the number of output is equal to two;
• memory means for storing the dither template values, said memory means being responsive to an address of an input cell of an input device to provide a dither template value which corresponds to the address of the input cell;
• and
• means for comparing an input level to the dither template value produced by said memory means to provide an output level which corresponds to the input level, wherein the dither template values are normalized by symmetrically distributing the dither template values between 0 and .DELTA..sub.Q, where .DELTA..sub.Q =(NIL-1)/(NOL-1), NIL is the number of input levels, and NOL is the number of output levels.

An imaging system comprising:

• an output device in which the number of output levels is equal to two;
• an input device which is capable of producing a number of input levels, the number of input levels being any number which is greater than to two;
• an image processor, coupled between said input and output devices, for translating the input levels to corresponding output levels, said image processor including:
• Look Up Table (LUT) generator means for generating dither template values for the input levels of said input device, wherein the dither template values are normalized by symmetrically distributing the dither template values between 0 and .DELTA..sub.Q, where .DELTA..sub.Q =(NIL-1)/(NOL-1), NIL is the number of input levels, and NOL is the number of output levels;
• memory means for storing the dither template values, said memory means being responsive to an address of an input cell of said input device to provide a dither template value which corresponds to the address of the input cell;
• and
• means for comparing an input level of an input cell to the dither template value produced by said memory means to provide an output level which corresponds to an input level.

A method of translating input levels of an imaging system to output levels, said method comprising the steps of:

• generating dither template values for the input levels of an imaging system, which has any number of input and two output levels, provided the number of input levels is greater than two;
• normalizing the dither template values by distributing the dither template values between 0 and .DELTA..sub.Q, where .DELTA..sub.Q =(NIL-1)/(NOL-1), NIL is the number of input levels, and NOL is the number of output levels;
• storing the dither template values in a memory means, said memory means being responsive to the address of an input cell of an input device to provide a dither template value which corresponds to the address of the input cell;
• comparing the dither template value output by the memory means in response to an address of the input cell to an input level of the input cell;
• and
• outputting an output level which corresponds to the input level based on the results of said comparing step.