Method and apparatus for compensating data image reproduced from holographic system
View Patent ↗The present invention provides a method and apparatus for preprocessing a page image reproduced from a storage medium in a holographic system. The present invention calculates pixel sums for each lines in the page image to select a maximum sum, calculates a modified maximum sum using the modified maximum sum and its neighboring sums, determines a compensation location for distorted pixels using the modified maximum sum and performs over-sampling a data image with reference to the compensation location of magnified pixels, to thereby compensate the data image with high precision in sub-pixels.
1. An apparatus for preprocessing a page image reproduced from a storage medium in a holographic system, wherein the page image includes a data image and upper, lower, left and right borders surrounding the data image, the apparatus comprising:
means for calculating pixel sums for each lines in the page image to select a maximum sum among the calculated sums at each upper, lower, left and right corner in the page image, wherein a pixel location corresponding to the maximum sum corresponds to a border;
means for calculating a modified maximum sum using the maximum sum and its neighboring sums, wherein a pixel location corresponding to the modified maximum sum corresponds to a modified location of the border;
means for calculating a distortion error between the position of the border and the modified location of the border to determine whether the calculated distortion error exceeds a half pixel;
means for determining a compensation location for distorted pixels using the modified maximum sum when it is determined that the calculated distortion error exceeds the half pixel; and
means for over-sampling pixels in the data image with reference to the compensation location.
2. The apparatus of claim 1 , wherein the means for calculating a modified maximum sum performs a curve fitting to find out the modified maximum sum,
wherein curve fitting is expressed as the Least Square Polynomial as follows:
Y=M 0 +M 1 X 1 + . . . +M (k−1) X (k−1) +M k X k
where k is a positive integer, Y denotes a maximum sum and its neighboring sums, and X denotes lines having the maximum sum and its neighboring sums.
3. The apparatus of claim 2 , wherein means for determining a compensation location performs a curve fitting to find out the compensation location,
wherein the curve fitting is expressed as the Least Square Polynomial as follows:
Y=M 0 +M 1 X 1 + . . . +M (k−1) X (k−1) +M k X k
where k is a positive integer, Y denotes a modified maximum sum and X denotes a line having the modified maximum sum.
4. The apparatus of claim 1 , wherein the neighboring sums include the sums arranged at left and right hands of the maximum sum.
5. The apparatus of claim 1 , wherein the compensation location represents a point where skipping three pixels at the time of over-sampling.
6. A method of preprocessing a page image reproduced from a storage medium in a holographic system, wherein the page image includes a data image and upper, lower, left and right borders surrounding the data image, the method comprising:
(a) the holographic system performing the steps of:
(b) calculating pixel sums for each lines in the page image to select a maximum sum among the calculated sums at upper, lower, left and right corner in the page image, wherein a pixel location corresponding to the maximum sum corresponds to a border location;
(c) calculating a modified maximum sum using the maximum sum and its neighboring sums, wherein a pixel location corresponding to the modified maximum sum corresponds to a modified location of the border;
(d) calculating a distortion error between the position of the border and the modified location of the border to determine whether the calculated distortion error exceeds a half pixel;
(e) determining a compensation location for distorted pixels using the modified maximum sum when it is determined that the calculated distortion error exceeds the half pixel; and
(f) over-sampling pixels in the data image with reference to the compensation location.
7. The method of claim 6 , wherein the step of calculating a modified maximum sum performs a curve fitting to find out the modified maximum sum,
wherein curve fitting is expressed as the Least Square Polynomial as follows:
Y=M 0 +M 1 X 1 + . . . +M (k−1) X (k−1) +M k X k
where k is a positive integer, Y denotes a maximum sum and its neighboring sums, and X denotes lines having the maximum sum and its neighboring sums.
8. The method of claim 7 , wherein the step of determining a compensation location performs a curve fitting to find out the compensation location,
wherein the curve fitting is expressed as the Least Square Polynomial as follows:
Y=M 0 +M 1 X 1 + . . . +M (k−1) X (k−1) +M k X k
where k is a positive integer, Y denotes a modified maximum sum and X denotes a line having the modified maximum sum.
9. The method of claim 6 , wherein the neighboring sums include the sums arranged at left and right hands of the maximum sum.
10. The method of claim 6 , wherein the compensation location represents a point where skipping three pixels at the time of over-sampling.