A sampling approach to ultra-fast object location
Davies, E.R.
Real-Time Imaging, 7, no. 4, 339–355 (2001)
This paper presents new work to
determine lowest bounds on the computation needed to locate objects in digital
images. While it was originally applied to the rapid location of cereal grains
for real-time inspection, the concepts are now being found useful as a rigorous
starting point for understanding general visual search, and have an interesting
relationship with the saccades of the human visual system. During 2007 this
generalisation has been published in an Electronics Letter (43(9), 508), and
slightly more fully in VIE 2007: a full version of the paper has been invited for
the journal AMCS and is in press.
Design of efficient line segment detectors for cereal grain inspection
Davies, E.R., Bateman, M., Mason, D.R., Chambers, J. and Ridgway, C.
Pattern Recogn. Lett., 24, nos. 1–3, 421–436 (2003)
This paper arose from a grant from the Home-Grown Cereals
Authority to carry out research in conjunction with DEFRA. It presents the
design of sensitive, robust, real-time algorithms for locating insects amongst
cereal grains. The algorithms take the form of efficient bar detectors, and have
been shown to be more effective than detectors based on edge detection. They
generalise to use as streak detectors, and significant interest has been shown
in their use for totally different applications, such as locating veins in human
retinal images. Thus the methodology is highly generic, applying well outside
the area of original motivation.
An analysis of the geometric distortions produced by
median and related image processing filters
Davies, E.R.
invited review in Advances in Imaging and Electron Physics, 126, 93–193 (2003)
This paper encapsulates and significantly extends Roy's work in understanding the exact
extent of the geometric distortions produced by median and related filters
(whose aim is largely to eliminate noise from digital images). While a continuum
approximation gave useful results, later discrete structural analysis eventually
led to essentially exact agreement between theory and experiment, so that the
subject could be regarded as satisfactorily closed, at least for grey-scale
images. This work includes theoretical models and experimental tests of the
shifts produced by the whole family of rank-order filters, and as such has
strong relevance and importance for mathematical morphology.
Mode filters and their effectiveness for processing colour images
Charles, D. and Davies, E.R.
Imaging Science, 52, no. 1, 3–25 (2004)
This paper investigates
the properties of mode filters in grey and colour images, and extends the work
of the previous paper (a) to the colour domain and (b) to provide detailed explanations of
the performance of mode filters. Somewhat surprisingly, it also shows
astonishing performance when applied to colour images with up to 70% impulse
noise, removing the noise almost completely and amounting to a breakthrough for
the low computation colour mode filter that had been devised in this work.
Hitherto, mode filters seemed to be mainly useful for image enhancement, but
their use for gross noise suppression is entirely new.