Patent ID: 7826616

Claim:
A method of converting an image bitmap comprising: defining a current rectangular region of the image bitmap; quantifying spectral characteristics of the current rectangular region; dividing the current rectangular region into four rectangular sub-regions in response to the spectral characteristics being greater than a predetermined threshold value; tagging the current rectangular sub-region as a terminal rectangular region in response to the spectral characteristics being less than or equal to the predetermined threshold value; tagging each rectangular sub-region as a terminal rectangular region in response to the size of the rectangular sub-region being less than or equal to a predetermined threshold value; defining one of the non-terminal rectangular sub-regions as the current rectangular region and repeating the above until all rectangular regions are tagged terminal; determining color characteristics for each of the terminal rectangular regions; and determining a split point common to all four rectangular sub-regions for subdividing the current rectangular region, wherein determining a split point comprises determining a center-of-gravity of the rectangular region based on color values of pixels in the rectangular region and an average luminance value of the rectangular region.