Method and apparatus for processing scanned image

1. A method for processing a scanned image, comprising:

a shaded region extracting step of extracting a region, which is shaded by a shading object and lies in a margin in vicinity of an edge of the scanned image, as a shaded region;

a pixel value repairing step of repairing values of pixels, which lie both in a line segment and the shaded region, by using a linear model according to known values of pixels, which lie both in the line segment and the margin, the line segment passing through the shaded region and being parallel to the edge;

estimating noises of pixels, which lie both in the line segment and the shaded region, according to values of known noises of pixels, which lie both in the line segment and the margin, the line segment passing through the shaded region and being parallel to the edge; and

adding the estimated noises to the repaired values of the pixels which lie both in the line segment and the shaded region.

2. The method according to claim 1 , wherein the shaded region extracting step comprises:

providing a point in the shaded region;

estimating a central value of pixels in a small window around the point;

calculating a difference between the central value and a value of each of pixels in a big window around the point; and

extracting the shaded region according to the difference by using binarization.

3. The method according to claim 2 , wherein before the shaded region extracting step, the method further comprises:

an automatic shaded region extracting step of extracting the shaded region automatically;

not performing the shaded region extracting step in case of a successful automatic extraction; and

performing the shaded region extracting step in case of an unsuccessful automatic extraction.

4. The method according to claim 3 , wherein after the shaded region extracting step, the method further comprises:

judging whether the shaded region extraction step is successful; and

providing a user interface to enable manual extraction of the shaded region manually in case of an unsuccessful automatic extraction.

5. An apparatus for processing a scanned image, comprising:

a shaded region extracting module configured to extract a region, which is shaded by a shading object and lies in a margin in vicinity of an edge of the scanned image, as a shaded region; and

a pixel value repairing module configured to repair values of pixels, which lie both in a line segment and the shaded region, by using a linear model according to values of pixels, which lie both in the line segment and the margin, the line segment passing through the shaded region and being parallel to the edge;

a noise estimating module configured to estimate noises of pixels, which lie both in the line segment and the shaded region, according to values of known noises of pixels, which lie both in the line segment and the margin, the line segment passing through the shaded region and being parallel to the edge; and

a noise adding module configured to add the estimated noises to the repaired values of the pixels which lie both in the line segment and the shaded region.

6. The apparatus according to claim 5 , wherein the shaded region extracting module comprises:

a point providing sub-module configured to provide a point in the shaded region;

a central pixel value estimating sub-module configured to estimate a central value of pixels in a small window around the point;

a difference calculating sub-module configured to calculate a difference between the central value and a value of each of pixels in a big window around the point; and

an extracting sub-module configured to extract the shaded region according to the difference by using binarization.

7. The apparatus according to claim 6 , further comprising:

an automatic extracting module configured to extract the shaded region automatically;

wherein if the automatic extracting module extracts the shaded region successfully, the shaded region extracting module does not perform the shaded region extraction, and if the automatic extracting module extracts the shaded region unsuccessfully, the shaded region extracting module performs the shaded region extraction.

8. The apparatus according to claim 7 , further comprising:

a judging module configured to judge whether the shaded region extracting module extracts the shaded region successfully; and

a user interface configured to enable manual extraction of the shaded region if the automatic extracting module extracts the shaded region unsuccessfully.