# Research on Authentic Signature Identification Method Integrating Dynamic and Static Features
## 4 Results
### Feature Extraction
#### 4.1.2 Static Feature Extraction  
Static features are the features extracted from offline signature images, which are similar to the results of visual analysis. They mainly distinguish different writers by analyzing the image structure, including the shape, position and writing style of the signature. The characteristics of the combined signatures are different through the different treatment methods of different strokes by the writers and the extracted static characteristics have a certain relationship with the public's cognitive judgment, which is easier for the public to understand.  
1. Aspect ratio It is the horizontal and vertical span of the signature image, such as Figure 12, which reflects the habits of the writer when writing the signature, such as flat or rounded. Although this is not a unique key feature, the writing characteristics reflected by the aspect ratio are less likely to change for different writers.
2. Area  
Figure 11: Minimum velocity.  
Figure 10: Maximum velocity.  
The area is the most basic feature to describe the size of the block pattern. The pattern area in the image can be represented by the number of pixels in the same marked area, as shown in Figure 13. This refers to the total number of pixels after the binarization image and the sample area reflect the size of signatures of different people to a certain extent. It is informative to supplement with the aspect ratio feature.  
The center of gravity of the signature is the center point of the weight for the whole signature, as shown in Figure 14. The center of gravity is the foundation of writing and a good grasp of the center of gravity will result in flatter words, which will vary from writer to writer.  
Among the axes that pass through the center of gravity of the graph, the longest axis is called the principal axis of the graph. The angle between the principal axis and the i-axis is called the principal axis direction angle \(\theta\), as in Figure 15, which can be used to represent the position of the signature graph.  
(5) Quadrilateral defining signature structure  
Figure 14: Graphic center of gravity. (**a**) A signature with a center of gravity A; (**b**) a signature with a center of gravity B.  
Figure 12: Aspect ratio. (**a**) A signature with a certain aspect ratio A; (**b**) a signature with a certain aspect ratio B.  
Figure 13: Area.  
For the signature, which has obvious personalized features and is not easy to change, it is possible to find some representative features that make a significant contribution to distinguishing different signatures. The strokes, such as horizontal, vertical, apostrophe, down, dot and hook, are all handled differently by different signers and the shape of the structural quadrilateral formed is also completely different. According to this feature, the general writing characteristics of the writer can be deduced. We processed the refined sample image to find the most edge points of the image in the four directions of up, down, left and right and connected the four edge points, in turn, to get a quadrilateral, as in Figure 16. When reflecting personal characteristics, we extract the four internal angles of the quadrilateral of the edge points.  
(6) Chain code for signature quadrilateral  
Starting from the construction of a vertex of a quadrilateral, mark the edges in anti-clockwise order and classify the boundary between each edge and the horizontal direction into chain codes of 0-7 different numbers, as shown in Figure 17. The chain code is adjusted on the basis of the direction of the meter character grid. According to the floating offset, when people write horizontally and vertically, the original direction of the meter character grid is expanded by 45 degrees to both sides; that is, the angle of each direction has a limit of 45 degrees, which can well eliminate the error caused by different handwriting