Patent ID: 11956402
Assignee: HEWLETT-PACKARD DEVELOPMENT COMPANY, L.P.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 13:
14. Non-transitory machine readable medium storing instructions which, when executed, cause a processor to:
derive a halftone threshold matrix from a greyscale image having a first number of grey levels and a plurality of non-binary pixels, wherein each non-binary pixel is associated with a grey level;
wherein deriving the halftone threshold matrix comprises:
increasing the number of grey levels in the image to a second number of grey levels by:
ordering the non-binary pixels based on their grey level;
taking then non-binary pixels in pixel order and the grey levels of the second number of grey levels in grey level order, allocate a grey level of the second number of grey levels to each non-binary pixel, evenly distributing the non-binary pixels between the grey levels; and
deriving a threshold value for each non-binary pixel which is proportional to the grey level of the non-binary pixel; wherein

the halftone threshold matrix comprises the threshold values for the non-binary pixels.