Apparatus and method for detecting horizon in sea image
AssigneeElectronics and Telecommunications Research Institute
InventorsJae Kwang Lee, Chang Joon Park, In Ho Lee
Life of this patent
Estimating the term…
Abstract
Provided is an apparatus and method for detecting a horizon which is necessary to detect a camera movement when compositing sea images in a marker-free sea-image camera tracking system. In the method, an ROI is selected near a horizon in a still image of the moving image of the sea, and each maximum point corresponding to the maximum brightness difference is detected from brightness differences between two pixels of each pair having two symmetrical pixels in each column of the ROI. The horizon is detected through a line-fitting using the maximum points. Therefore, the result of horizon detection can be very stable and a horizon can be easily detected in a sea scene having hundreds of frames.
Claims16
An apparatus, comprising:
- a region-of-interest (ROI) detection unit that detects coordinates of an ROI selected in a still image corresponding to a frame of a moving sea image;
- and
- a control unit that
- detects a horizon corresponding to a line-fitting in the ROI of the still image determined by the detected coordinates,
- calculates parameters a and b as Eigenvalues of the following matrix A,
- A
- =
-
- [
- ∑
- xrel
-
- (
- i
- )
- 2
- ∑
- xrel
-
- (
- i
- )
- *
- yrel
-
- (
- i
- )
- ∑
- xrel
-
- (
- i
- )
- *
- yrel
-
- (
- i
- )
- ∑
- yrel
-
- (
- i
- )
- 2
- ]
- ,
- where the shifted maximum points are xrel(i) and yrel(i), respectively,
- calculates a parameter c by substituting the parameters a and b and center coordinates (xm, ym) into a line equation expressed as ax+by+c=0, and
- uses the calculated parameters a, b and c in a horizon equation.
A method, comprising:
- designating an ROI (region-of-interest) in a still image corresponding to a frame of a moving sea image;
- detecting a horizon corresponding to a line-fitting in the ROI of the still image;
- calculating parameters a and b as Eigenvalues of the following matrix A,
- A
- =
- [
- ∑
- xrel
-
- (
- i
- )
- 2
- ∑
- xrel
-
- (
- i
- )
- *
- yrel
-
- (
- i
- )
- ∑
- xrel
-
- (
- i
- )
- *
- yrel
-
- (
- i
- )
- ∑
- yrel
-
- (
- i
- )
- 2
- ]
- where the shifted maximum points are xrel(i) and yrel(i), respectively;
- calculating a parameter c by substituting the parameters a and b and center coordinates (xm, ym) into a line equation expressed as ax+by+c=0;
- and
- using the calculated parameters a, b and c in a horizon equation.
Dependencies are inferred from the claim text.