Related Experiment Video
Updated: Oct 9, 2026

Multimodal Cross-Device and Marker-Free Co-Registration of Preclinical Imaging Modalities
Published on: October 27, 2023
Phase congruency: a low-level image invariant
1Department of Computer Science, University of Western Australia, Nedlands, W.A. 6907. pk@cs.uwa.edu.au
Abstract:
Phase congruency is a low-level invariant property of image features. Interest in low-level image invariants has been limited. This is surprising, considering the fundamental importance of being able to obtain reliable results from low-level image operations in order to successfully perform any higher level operations. However, an impediment to the use of phase congruency to detect features has been its sensitivity to noise. This paper extends the theory behind the calculation of phase congruency in a number of ways. An effective method of noise compensation is presented that only assumes that the noise power spectrum is approximately constant. Problems with the localization of features are addressed by introducing a new, more sensitive measure of phase congruency. The existing theory that has been developed for 1D signals is extended to allow the calculation of phase congruency in 2D images. Finally, it is argued that high-pass filtering should be used to obtain image information at different scales. With this approach, the choice of scale only affects the relative significance of features without degrading their localization.
Related Concept Videos
Perceptual Constancy
Size constancy is the recognition that an object remains the same size, even when its image on the retina changes. For instance, a bus is perceived to be large enough to carry people, even if it looks tiny from...
Gestalt Principles of Perception
Phase Contrast and Differential Interference Contrast Microscopy
In-phase-contrast microscopes, interference between light directly passing through a cell and light refracted by cellular components is used to create high-contrast, high-resolution images without staining. It is the oldest and simplest type of microscope that creates an image by altering the wavelengths of light rays passing through the specimen. Altered wavelength paths are created using an annular stop in the condenser. The annular stop produces a hollow cone of...
Convolution Properties II
The width property indicates that if the durations of input signals are T1 and T2, then the width of the output response equals the sum of both durations, irrespective of the shapes of the two functions. For instance, convolving two rectangular pulses with durations of 2 seconds and 1 second results in a function with a width of 3 seconds.
The area property asserts that the area under the...
Convolution Properties I
The commutative property reveals that the input and the impulse response of an LTI (Linear Time-Invariant) system can be interchanged without affecting the output:
Depth Perception and Spatial Vision
