Patent ID: 7844118

Claim:
A method for processing image data, the method comprising: receiving contone image data via an input device, the image data comprising a plurality of pixels; using a processor to process the image data and determine a presence of thin lines, wherein each determined thin line comprises at most four pixels along its width, the processing including: (a) processing the image data using a first thin line detection method to determine a first result for the presence of thin lines, the processing comprising: establishing a window comprising a pixel of interest and neighboring pixels; determining a minimum value and a maximum value in a selected subset of pixels in the window; thresholding the pixel of interest and neighboring pixels of the window using thresholds; converting the pixels in the window, after thresholding, into a binary window of image data comprising a plurality of binary pixels, the binary pixels including a number of on and off pixels; determining characteristics associated with the on pixels in each row and column of the binary window; thresholding the characteristics associated with the on pixels and off pixels of the binary window; determining if a thin line exists in the window based on the thresholding of the characteristics associated with the on pixels and off pixels; and classifying the pixel of interest as an edge pixel that is part of a thin line if it is determined that the thin line exists; (b) processing the image data using a second thin line detection method to determine a second result for the presence of thin lines, the processing comprising: establishing a window comprising a pixel of interest and neighboring pixels, the window comprising a plurality of predetermined regions; determining a minimum value and a maximum value of a selected subset of pixels in the window; thresholding the pixel of interest and neighboring pixels of the window using a first set of thresholds; counting a number of pixels in each of the predetermined regions of the window after applying the first set of thresholds; thresholding the counted number of pixels using a second set of thresholds; determining if a thin line exists in the window based on the thresholding of the counted number of pixels; and classifying the pixel of interest as an edge pixel that is part of a thin line if it is determined that the thin line exists and that the pixel of interest is part of the thin line; and combining the first result and the second result of the processed image data from the first thin line detection method and the second thin line detection method to produce a thin line determination in the image data.