Methods and systems for segmenting a digital image into regions
Aspects of the present invention relate to methods and systems for segmenting a digital image into regions. A frequency-of-occurrence of image values may be determined excluding a portion of pixels in a digital image. An image value associated with a peak in the frequency-of-occurrence of image values may be identified and associated with an image label. Pixel locations may be labeled based on the associated labels and image values. Additionally, unreliable pixels may be determined and labeled based on the associated labels and image values.
1. A method for segmenting a digital image into regions, said method comprising:
a. in a computing system comprising at least one computing device, determining a frequency-of-occurrence of a plurality of pixel values in a digital image comprising pixels, wherein said determining comprises excluding at least one of said pixels in said digital image from said determining;
b. identifying at least one pixel value associated with a peak frequency-of-occurrence;
c. associating said at least one pixel value with an image label, thereby producing an association between said at least one pixel value and said image label;
d. determining a candidate pixel location in said digital image;
e. labeling said candidate pixel location based on said association;
f. determining an unreliable-pixel location in said digital image, wherein said unreliable-pixel location is not said candidate pixel location;
g. determining a class label for said unreliable-pixel location based on said association between said at least one pixel value and said image label;
h. accumulating a frequency-of-occurrence of said image label among a plurality of neighboring pixel labels; and
i. labeling said unreliable-pixel location based on a comparison between a threshold value and said frequency-of-occurrence of said image label among said plurality of neighboring pixel labels.
2. The method of claim 1 , wherein said plurality of neighboring pixel labels is associated with a four-nearest-neighbor neighborhood in relation to said unreliable-pixel location.
3. The method of claim 1 , wherein said plurality of neighboring pixel labels is associated with a neighborhood of previously scanned neighboring pixels.
4. The method of claim 1 further comprising generating a look-up-table wherein said look-up-table comprises said association between said at least one pixel value and said image label.
5. The method of claim 1 wherein said determining a frequency-of-occurrence further comprises generating a histogram.
6. The method of claim 5 further comprising smoothing said histogram.
7. The method of claim 1 wherein said at least one excluded pixel in said digital image comprises a pixel that is a portion of a text region.
8. The method of claim 1 wherein said determining a candidate pixel location comprises one or more of a uniformity measure, a variance measure, and a text measure.
9. The method of claim 1 wherein said image label indicates a local background region.
10. A system for classifying a region in a digital image, said system comprising:
a. a counter, in a computing device, for counting a frequency-of-occurrence of a plurality of pixel values in a digital image comprising pixels, wherein said counting comprises excluding at least one of said pixels in said digital image from said counting;
b. an identifier for identifying at least one pixel value associated with a peak frequency-of-occurrence;
c. an associator for associating said at least one pixel value with an image label, thereby producing an association between said at least one pixel value and said image label;
d. a first determiner for determining a candidate pixel location in said digital image;
e. a first labeler for labeling said candidate pixel location in said digital image based on said association;
f. a second determiner for determining an unreliable-pixel location in said digital image, wherein said unreliable-pixel location is not said candidate pixel location;
g. a labeler determiner for determining a class label for said unreliable-pixel location based on said association between said at least one pixel value and said image label;
h. an accumulator for accumulating a frequency-of-occurrence of said image label among a plurality of neighboring pixel labels; and
i. an unreliable-pixel labeler for labeling said unreliable-pixel location based on a comparison between a threshold value and said frequency-of-occurrence of said image label among said plurality of neighboring pixel labels.
11. The system of claim 10 , wherein said plurality of neighboring pixel labels is associated with a four-nearest-neighbor neighborhood in relation to said unreliable-pixel location.
12. The system of claim 10 , wherein said plurality of neighboring pixel labels is associated with a neighborhood of previously scanned neighboring pixels.
13. The system of claim 10 further comprising a generator for generating a look-up-table wherein said look-up-table comprises said association between said at least one pixel value and said image label.
14. The system of claim 10 wherein said at least one excluded pixel in said digital image comprises a pixel that is a portion of a text region.
15. The system of claim 10 wherein said plurality of pixel values comprise color values in a luminance-chrominance color space.
16. The system of claim 10 wherein said image label indicates a local background region.