Method and apparatus for coalescing a grayscale image and rendering the coalesced grayscale image as a binary image
AssigneeLaserMaster Corporation
InventorsSteven L. Lidke, Reed R. Esau
Life of this patent
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Abstract
Pixels in a grayscale image are identified for coalescing based on a corresponding value in a threshold matrix. This threshold matrix value is then used to determine both the color and number of pixels to be coalesced at this location. Grayscale pixels are then coalesced based on pixels which will ultimately be the same color as the identified pixel. The coalesced grayscale image is then compared on a pixel-by-pixel basis to corresponding values in the threshold matrix to determine a halftone image.
Claims14
A method of forming a halftone image from a grayscale image, the method including:
- identifying intensity threshold values from a lookup table for each of a plurality of selected pixel positions in the grayscale image;
- and
- coalescing similar grayscale pixels in the grayscale image neighboring each selected pixel position based on the intensity threshold value associated with the selected pixel position and intensity information of neighboring pixels to form coalesced grayscale image information.
A method of forming halftone pixels to form a halftone image from grayscale pixels arranged to form a grayscale image comprising:
- rearranging grayscale pixels in selected local neighborhoods comprising a plurality of grayscale pixels within the grayscale image based on an intensity value associated with a selected local neighborhood and intensity values of neighboring pixels within the selected local neighborhood;
- and
- converting grayscale pixels resulting from the rearranging grayscale pixels step to form halftone pixels forming a halftone image.
A printing device for receiving a grayscale image and providing a corresponding halftone image, the printing device comprising:
- storage means for storing a lookup table having threshold values associated with each pixel within the grayscale image;
- means for identifying intensity threshold values from the lookup table for each of a plurality of selected pixel positions in the grayscale image;
- means for coalescing similar grayscale pixels in the grayscale image neighboring each selected pixel position based on the intensity threshold value associated with the selected pixel position and intensity information of neighboring pixels to form coalesced grayscale image information;
- and
- means for comparing coalesced grayscale image information on a pixel by pixel basis with corresponding intensity threshold values from the lookup table to form a halftone image.
A method for rendering a halftone image from a grayscale image including:
- identifying grayscale pixels within the grayscale image for coalescing based on a comparison of a lookup table value corresponding to each grayscale pixel with a preselected range of values;
- identifying a halftone pixel color for each grayscale pixel identified for coalescing based on a comparison of grayscale pixel intensity with a corresponding lookup table value;
- and
- coalescing grayscale pixels neighboring each grayscale pixel identified for coalescing that if coalesced has the same color as the corresponding grayscale pixel identified for coalescing.
Dependencies are inferred from the claim text.