An apparatus for processing data describing an image is provided with an input device, a binarizing device, a correcting device, a driving pulse generating device, and an adjusting device. The input device inputs the data. The binarizing device performs a binarizing calculation on the input data. The correcting device corrects the binarizing calculation when a pixel that needs adjustment of a driving pulse thereof has been identified based on the binarized data. The driving pulse generating device generates driving pulses based on the binarized data. The adjusting device adjusts the driving pulse when the pixel that needs adjustment of the driving pulse thereof has been identified based on the binarized data.