Method for entropy-based determination of object edge curves

• US 8,682,067 B2
• Filed: 02/09/2010
• Issued: 03/25/2014
• Est. Priority Date: 02/19/2009
• Status: Active Grant

• Current Assignee: Airbus Defence and Space GmbH
• Original Assignee: EADS Deutschland GmbH (Airbus SE)
• Inventors: Hiebl, Manfred
• Primary Examiner(s): Wu, Jingge
• Application Number:
  US13/202,246
• Publication Number:
  US 20120033877A1
• Time in Patent Office: 1,505 Days
• Field of Search: 382/165, 382/173
• US Class Current: 382/165
• CPC Class Codes: G06T 2207/10024 Color image
• CPC Class Codes: G06T 2207/10036 Multispectral image; Hyperspectral image
• CPC Class Codes: G06T 2207/10048 Infrared image
• CPC Class Codes: G06T 2207/20012 Locally adaptive
• CPC Class Codes: G06T 2207/20076 Probabilistic image processing
• CPC Class Codes: G06T 2207/30184 Infrastructure
• CPC Class Codes: G06T 2207/30212 Military
• CPC Class Codes: G06T 2207/30252 Vehicle exterior; Vicinity of vehicle
• CPC Class Codes: G06T 7/13 Edge detection
• CPC Class Codes: G06T 7/143 involving probabilistic approaches, e.g. Markov random field [MRF] modelling
• CPC Class Codes: G06V 10/443 by matching or filtering
• CPC Class Codes: G06V 20/13 Satellite images

Abstract

In a method for determining object edge curves in a recorded image of a multispectral camera, the image recorded is converted into a false color image, hue value from the HSV color space is assigned to each pixel in the false color image such that the hue value corresponds to a hue angle on a predetermined color circle, and the pixels are classified as object pixels and background pixels, such that those pixels with hue values that are within a predetermined value range are defined as the object pixels. An entropy profile is then determined by way of a displaceable evaluation window, such that the entropy of mixing S is calculated for each pixel from the object pixels and background pixels according to the equation:

$S=-k\left(n_A\ln \frac{n_A}{n_A+n_B}+n_B\ln \frac{n_B}{n_A+n_B}\right)$
where n_A denotes the number of object pixels within the evaluation window, n_B denotes the number of background pixels within the evaluation window and k is a proportionality factor.

Claims

1. A method for determining object edge curves in a recorded image of a multispectral camera comprising:

converting the image recorded into a false color image,

assigning a hue value from a HSV color space to each pixel in the false color image, such that the hue value corresponds to a hue angle on a predetermined color circle,

classifying the pixels as object pixels and background pixels, such that pixels with hue values that are within a predetermined value range are defined as the object pixels,

determining an entropy profile, by way of a displaceable evaluation window, such that the entropy of mixing S is calculated for each pixel in the recorded image from the object pixels and background pixels according to the equation

2. The method according to claim 1, wherein, for determining the entropy profile, the entropy of mixing is calculated in an evaluation window of a predefinable length and width, such that the evaluation window is displaceable via the pixel classification created and the calculated entropy of mixing S assigned to the respective main pixel of the evaluation window, and further comprising shifting the evaluation window by at least one pixel in a direction of length, width, or both length and width, and repeatedly determining the entropy profile until an entropy of mixing has been assigned to each pixel.