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Hough transforms are techniques for object detection, a critical step in many implementations of computer vision, or data mining from images. Specifically, the Randomized Hough transform is a probabilistic variant to the classical Hough transform, and is commonly used to detect curves (straight line, circle, ellipse, etc.) [1] The basic idea of Hough transform (HT) is to implement a voting ...
The Hough transform is a feature extraction technique used in image analysis, computer vision, pattern recognition, and digital image processing. [1] [2] The purpose of the technique is to find imperfect instances of objects within a certain class of shapes by a voting procedure.
The generalized Hough transform (GHT), introduced by Dana H. Ballard in 1981, is the modification of the Hough transform using the principle of template matching. [1] The Hough transform was initially developed to detect analytically defined shapes (e.g., line, circle, ellipse etc.). In these cases, we have knowledge of the shape and aim to ...
The Hough transform [3] can be used to detect lines and the output is a parametric description of the lines in an image, for example ρ = r cos(θ) + c sin(θ). [1] If there is a line in a row and column based image space, it can be defined ρ, the distance from the origin to the line along a perpendicular to the line, and θ, the angle of the perpendicular projection from the origin to the ...
Feature enhancement in an image (St Paul's Cathedral, London) using Phase Stretch Transform (PST). Left panel shows the original image and the right panel shows the detected features using PST. The phase stretch transform or PST is a physics-inspired computational approach to signal and image processing. One of its utilities is for feature ...
Because smooth surfaces are locally planar, affine invariant features are appropriate for matching: the paper detects ellipse-shaped regions of interest using both edge-like and blob-like features, and as per [Lowe 2004], finds the dominant gradient direction of the ellipse, converts the ellipse into a parallelogram, and takes a SIFT descriptor ...
The circle Hough Transform (CHT) is a basic feature extraction technique used in digital image processing for detecting circles in imperfect images. The circle candidates are produced by “voting” in the Hough parameter space and then selecting local maxima in an accumulator matrix. It is a specialization of the Hough transform.
Moreover, the Radon transform does not capture the detection of circles or ellipses, which are also very common applications of the Hough transform. Although the Wikipedia article on the Hough transform is (or at least was) not very well written, it (at least roghly) reflects the notions of how the Hough transform is taught in image processing ...