Patent ID: 6922196
Filing Date: 2005-07-26
Classification: H04N

Abstract:
1. A method for transforming a digitized image, said method comprising: providing said image as a plurality of pixels, wherein data for each pixel is in a first format which is a grey scale image; and processing said data of each of said pixels by employing data from a region of interest which includes at least one pixel following said each of said pixels, and includes a plurality of neighboring pixels, and producing a second format which is a binary image, and said method further comprising determining a dynamic range of pixel values of pixels in an encompassing neighborhood of the region of interest, and wherein the step of processing includes making dynamic adjustments depending on the dynamic range of pixel values, wherein the step of making said dynamic adjustments includes producing a visually pleasing transition between text and picture areas in said image; and wherein said producing a visually pleasing transition includes: if said dynamic range is high, implying said pixels in said encompassing neighborhood of said region of interest are in a text area or a line art area or in an area of an image that has a high contrast edge, wherein the edges of said text area, line art area and area of an image having high contrast edge are sharpened by computing a pixel data threshold value for said region of interest; and comparing each pixel value in said region of interest to said pixel data threshold; if said pixel value is greater than the pixel data threshold value, a first value is placed in the corresponding position of the said second format image; if said pixel value is less than or equal to the pixel data threshold value, a second value is placed in the corresponding position of the said second format image; if said dynamic range is medium, computing a desired number of second values to be placed in said second format image in the region of interest; ordering the pixels in the region of interest according to the ordering of a predetermined halftone array; altering the order of a pixel in said ordering if said pixel has a value which is greater than the value of the next pixel in said order by a predetermined reordering threshold value; repeating said altering of the pixel order until the first and second values chosen for the second format image are no longer changed; choosing said desired number of second values for the second format from the beginning of the said order, and assigning the remaining pixels values in the region of interest to said first value; if said dynamic range is low, using said predetermined halftone array to compute said first and second values for said second format image.