Patent ID: 6166824
Filing Date: 2000-12-26
Classification: H04N

Abstract:
A print data processing apparatus comprising:a memory that stores dot image data;a plurality of irreversible compression devices that can be started when a capacity of the memory is insufficient to store dot image data, the irreversible compression devices irreversibly compressing the dot image data by thinning the dot image data and storing the compressed dot image data into the memory wherein the irreversible compression devices include:a simple thinning device that, if the dot image data is character data, symbol data, or data binarized in an error diffusion mode, deletes every other row of dot data and every other column of dot data,a second thinning device that, if the dot image data has been binarized in a fatting dithering mode, reduces the amount of the dot image data using error evaluation of rows and columns of dot data; anda third thinning device that, if the dot image data has been binarized in Bayer dithering mode, reduces the amount of the dot image data using weighted error evaluation of rows and columns of dot data;a compression mode selection device that, if the capacity of the memory is insufficient to store dot image data, selects one of the plurality of irreversible compression devices depending on whether the dot image data is at least one of character data, symbol data, draft printing data or image data and starts the selected irreversible compression device; anda printing device that prints the dot image data which has been compressed and stored in the memory by the selected irreversible compression device.