Black ink use determination methods and black ink use determination device

摘要

PROBLEM TO BE SOLVED: To prevent deterioration in quality of a recorded image by replacing each signal with black ink and recording the resulting signal when all density levels of each received signal are over a prescribed threshold level. SOLUTION: In the case that all density levels of each input signal are more than a prescribed threshold level, the signal is replaced with black ink and the resulting signal is recorded. The black ink use discrimination device receives a multi-value color signal from an input terminal 101 and an N-value processing section 102 applies N value error spread processing (N is an integer being 2 or over) to any of multi-value color signals 0-(N-1) sequentially from a low density to a high density to conduct N-value processing. A multi-value comparison section 105 applies threshold level discrimination as to whether or not three primary colors configuring the multi-value color signal have a prescribed density or over and the discrimination result is outputted to an image signal selection section 104. An image signal selection section 104 selects a signal receive from the N value processing section 102 or a signal received from a black signal generating section 103 depending on a signal received from a multi- value comparator section 105 and outputs the selected signal to a printer section 106.