METHOD AND SYSTEM FOR DECODING TWO-DIMENSIONAL CODE USING WEIGHTED AVERAGE GRAY-SCALE ALGORITHM

• US 20180137321A1
• Filed: 01/15/2018
• Published: 05/17/2018
• Est. Priority Date: 07/23/2015
• Status: Active Grant

• Current Assignee: Fujian Landi Commercial Technology Company Limited
• Original Assignee: Fujian Landi Commercial Equipment Co., Ltd. (Ingenico Group SA)
• Inventors: Jiang, Shengzhang, Wu, Weidong
• Granted Patent: US 10,108,835 B2
• Time in Patent Office: Days
• CPC Class Codes: G06K 7/10 by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
• CPC Class Codes: G06K 7/1417 2D bar codes
• CPC Class Codes: G06T 7/12 Edge-based segmentation
• CPC Class Codes: G06T 7/136 involving thresholding
• CPC Class Codes: G06T 7/187 involving region growing; involving region merging; involving connected component labelling

Abstract

The invention provides a method and system for decoding two-dimensional code using weighted average gray-scale algorithm. The method comprises: segmenting a received two-dimensional code image into bit regions each containing one bit data; presetting a shifting threshold, and shifting four original boundary lines of the bit region outwards by a distance of the shifting threshold to obtain four preset boundary lines; calculating an average gray-scale value of the bit region using the weighted average algorithm by taking an overlapping area between pixels inside the four preset boundary lines and the bit region as a weight; binarizing the two-dimensional code image according to the average gray-scale value of the bit region; and decoding the two-dimensional code image. The influence of the pixels which have an overlapping area with the bit region on the average gray-scale value of the bit region is considered, and the decoding accuracy and success rate are high.

Claims

1. A method for decoding two-dimensional code using weighted average gray-scale algorithm, characterized by comprising:

segmenting a received two-dimensional code image into bit regions each containing one bit data;

presetting a shifting threshold, and shifting four original boundary lines of the bit region outwards by a distance of the shifting threshold to obtain four preset boundary lines;

calculating an average gray-scale value of the bit region using the weighted average algorithm by taking an overlapping area between pixels inside the four preset boundary lines and the bit region as a weight;

binarizing the two-dimensional code image according to the average gray-scale value of the bit region; and

decoding the binarized two-dimensional code image.

2. The method for decoding two-dimensional code using weighted average gray-scale algorithm according to claim 1, wherein the shifting threshold is less than or equal to the width of one pixel.

3. The method for decoding two-dimensional code using weighted average gray-scale algorithm according to claim 1, wherein a solution of calculating the overlapping area between pixels inside the four preset boundary lines and the bit region includes:

finding all the pixels inside the four preset boundary lines;

selecting one selected point from the pixels and recording coordinates of the selected point and a position relationship between the selected point and boundary lines of the pixels;

calculating distances from the selected point to the four original boundary lines of the bit region and their position relationships;

calculating a length and a width of the overlapping area between the pixels and the bit region; and

calculating the overlapping area between the pixels and the bit region.

4. The method for decoding two-dimensional code using weighted average gray-scale algorithm according to claim 3, wherein the selected point is any one of the pixels.

5. The method for decoding two-dimensional code using weighted average gray-scale algorithm according to claim 3, wherein calculating an average gray-scale value of the bit region using the weighted average algorithm by taking the overlapping area between pixels inside the four preset boundary lines and the bit region as a weight specifically includes:

assuming that k represents the number of pixels inside the four preset boundary lines, P_i, represents pixels, where i=1, 2, . . . , k, S_i represents the overlapping area between the pixels P_i and the bit region, S represents the area of the bit region, Gp_i represents the gray-scale value of the pixels P_i, and Gave represents the average gray-scale value of the bit region, then the average gray-scale value Gave of the bit region is;

6. The method for decoding two-dimensional code using weighted average gray-scale algorithm according to claim 3, wherein calculating an average gray-scale value of the bit region using the weighted average algorithm by taking the overlapping area between pixels inside the four preset boundary lines and the bit region as a weight specifically includes:

assuming that k represents the number of pixels inside the four preset boundary lines, P_i represents pixels, where i=1, 2, . . . , k, S_i represents the overlapping area between the pixels P_i and the bit region, Gp_i represents the gray-scale value of the pixel P_i, and Gave represents the average gray-scale value of the bit region, then the average gray-scale value Gave of the bit region is;

7. The method for decoding two-dimensional code using weighted average gray-scale algorithm according to claim 1, wherein binarizing the two-dimensional code image according to the average gray-scale value of the bit region specifically includes:

calculating a gray-scale threshold of the two-dimensional code image according to the average gray-scale value of the bit region by using the Otsu method; and

binarizing the bit region according to the gray-scale threshold so as to obtain the binarization of the two-dimensional code image.

8. The method for decoding two-dimensional code using weighted average gray-scale algorithm according to claim 1, wherein binarizing the two-dimensional code image according to the average gray-scale value of the bit region specifically includes:

calculating a gray-scale threshold of the two-dimensional code image according to the average gray-scale value of the bit region by using the average value algorithm; and

binarizing the bit region according to the gray-scale threshold so as to obtain the binarization of the two-dimensional code image.

9. A system for decoding two-dimensional code using weighted average gray-scale algorithm, characterized by comprising:

a segmenting module which is configured for segmenting a received two-dimensional code image into bit regions each containing only one bit data;

a shifting module which is configured for shifting four original boundary lines of the bit region outwards by a distance of the shifting threshold to obtain four preset boundary lines;

a calculating module which is configured for calculating an average gray-scale value of the bit region using the weighted average algorithm by taking the overlapping area between pixels inside the four preset boundary lines and the bit region as a weight;

a binarizing module which is configured for binarizing the two-dimensional code image according to the average gray-scale value of the bit region; and

a decoding module which is configured for decoding the binarized two-dimensional code image.