Method and apparatus for correcting perspective of road image

Patent metadata

Field	Value
Publication number	US-12423853-B2
Application number	US-202217976367-A
Country	US
Kind code	B2
Filing date	Oct 28, 2022
Priority date	Dec 21, 2021
Publication date	Sep 23, 2025
Grant date	Sep 23, 2025

Abstract

A method and apparatus for processing an image. The method may include: acquiring a top view of a road; identifying a position of a lane line from the top view; cutting the top view into at least two areas, and determining, according to the position of the lane line in each area, a width of a lane in the each area and an average width of the lane in the top view; calculating a first perspective correction matrix by optimizing a first loss function, the first loss function being used to represent a difference between the width of the lane in the each area and the average width of the lane in the top view; and performing a lateral correction on the top view through the first perspective correction matrix to obtain a first corrected image.

First claim

What is claimed is:

1. A method for processing an image, comprising:
acquiring a top view of a road;
identifying a position of a lane line from the top view;
cutting the top view into at least two areas, and determining, according to the position of the lane line in each area, a width of a lane in the each area and an average width of the lane in the top view;
calculating a first perspective correction matrix by optimizing a first loss function, the first loss function being used to represent a difference between the width of the lane in the each area and the average width of the lane in the top view; and
performing a lateral correction on the top view through the first perspective correction matrix to obtain a first corrected image.

2. The method according to claim 1 , further comprising:
identifying a dashed lane line from the top view;
determining a length of the dashed lane line in the each area and an average length of the dashed lane line in the top view;
calculating a second perspective correction matrix by optimizing a second loss function, the second loss function being used to represent a difference between the length of the dashed lane line in the each area and the average length of the dashed lane line in the top view; and
performing a longitudinal correction on the first corrected image through the second perspective correction matrix to obtain a second corrected image.

3. The method according to claim 1 , wherein the identifying the position of the lane line from the top view comprises:
identifying a pixel and type of the lane line from the top view through a semantic segmentation model, to generate a semantic segmentation image; and
extracting the position of the lane line from the semantic segmentation image.

4. The method according to claim 3 , wherein the extracting the position of the lane line from the semantic segmentation image comprises:
transforming the semantic segmentation image into a binary image;
performing a contour detection on the binary image to obtain a rectangular contour;
splitting the rectangular contour into a plurality of segments along a direction of a long side of the rectangular contour, and performing the contour detection on each segment again to generate a plurality of sub-contours;
extracting a center line of each sub-contour rectangle as a linear vector of the lane line; and
fitting the linear vector of the lane line through a quadratic curve, and predicting and supplementing a missing part of the lane line.

5. The method according to claim 1 , wherein the determining, according to the position of the lane line in the each area, the width of the lane in the each area and the average width of the lane in the top view comprises:
performing a near neighbor search on the identified lane line, and pairing each two lane lines to obtain a matching pair set, wherein each matching pair corresponds to one lane;
calculating, for each lane, a lane width of a middle position of the each area as a width of the lane in the each area; and
calculating the average width of the lane in the top view based on the width of the lane in the each area.

6. The method according to claim 2 , wherein the determining the length of the dashed lane line in the each area and the average length of the dashed lane line in the top view comprises:
using, for the each area, a length of a complete dashed lane line in middle of the area as the length of the dashed lane line in the area; and
calculating the average length of the dashed lane line based on the length of the dashed lane line in the each area.

7. The method according to claim 1 , wherein the acquiring the top view of the road comprises:
acquiring a panoramic view of the road; and
transforming the panoramic view into the top view through a perspective projection method.

8. An electronic device, comprising:
at least one processor; and
a memory, communicatively connected to the at least one processor,
wherein the memory stores an instruction executable by the at least one processor, and the instruction is executed by the at least one processor, to enable the at least one processor to perform operations, the operations comprising:
acquiring a top view of a road;
identifying a position of a lane line from the top view;
cutting the top view into at least two areas, and determining, according to the position of the lane line in each area, a width of a lane in the each area and an average width of the lane in the top view;
calculating a first perspective correction matrix by optimizing a first loss function, the first loss function being used to represent a difference between the width of the lane in the each area and the average width of the lane in the top view; and
performing a lateral correction on the top view through the first perspective correction matrix to obtain a first corrected image.

9. The electronic device according to claim 8 , further comprising:
identifying a dashed lane line from the top view;
determining a length of the dashed lane line in the each area and an average length of the dashed lane line in the top view;
calculating a second perspective correction matrix by optimizing a second loss function, the second loss function being used to represent a difference between the length of the dashed lane line in the each area and the average length of the dashed lane line in the top view; and
performing a longitudinal correction on the first corrected image through the second perspective correction matrix to obtain a second corrected image.

10. The electronic device according to claim 8 , wherein the identifying the position of the lane line from the top view comprises:
identifying a pixel and type of the lane line from the top view through a semantic segmentation model, to generate a semantic segmentation image; and
extracting the position of the lane line from the semantic segmentation image.

11. The electronic device according to claim 10 , wherein the extracting the position of the lane line from the semantic segmentation image comprises:
transforming the semantic segmentation image into a binary image;
performing a contour detection on the binary image to obtain a rectangular contour;
splitting the rectangular contour into a plurality of segments along a direction of a long side of the rectangular contour, and performing the contour detection on each segment again to generate a plurality of sub-contours;
extracting a center line of each sub-contour rectangle as a linear vector of the lane line; and
fitting the linear vector of the lane line through a quadratic curve, and predicting and supplementing a missing part of the lane line.

12. The electronic device according to claim 8 , wherein the determining, according to the position of the lane line in the each area, the width of the lane in the each area and the average width of the lane in the top view comprises:
performing a near neighbor search on the identified lane line, and pairing each two lane lines to obtain a matching pair set, wherein each matching pair corresponds to one lane;
calculating, for each lane, a lane width of a middle position of the each area as a width of the lane in the each area; and
calculating the average width of the lane in the top view based on the width of the lane in the each area.

13. The electronic device according to claim 9 , wherein the determining the length of the dashed lane line in the each area and the average length of the dashed lane line in the top view comprises:
using, for the each area, a length of a complete dashed lane line in middle of the area as the length of the dashed lane line in the area; and
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Assignees

• Beijing Baidu Netcom Sci & Tech Co Ltd

Inventors

• Cai Junjie
• Zhong Kai
• Yang Jianzhong
• Xia Deguo
• Zhang Tongbin
• Lu Zhen

Classifications

• G06T2207/30256

  Lane; Road marking · CPC title

• G06V20/588 Primary

  Recognition of the road, e.g. of lane markings; Recognition of the vehicle driving pattern in relation to the road · CPC title

• G06V10/44

  Local feature extraction by analysis of parts of the pattern, e.g. by detecting edges, contours, loops, corners, strokes or intersections; Connectivity analysis, e.g. of connected components · CPC title

• G06T5/80

  Geometric correction · CPC title

• G06V10/24

  Aligning, centring, orientation detection or correction of the image · CPC title