A 3D-polar Coordinate Colour Representation Suitable for Image Analysis
نویسندگان
چکیده
The processing and analysis of colour images has become an important area of study and application. The representation of the RGB colour space in 3D-polar coordinates (hue, saturation and brightness) can sometimes simplify this task by revealing characteristics not visible in the rectangular coordinate representation. The literature describes many such spaces (HLS, HSV, etc.), but many of them, having been developed for computer graphics applications, are unsuited to image processing and analysis tasks. We describe the flaws present in these colour spaces, and present three prerequisites for 3D-polar coordinate colour spaces well-suited to image processing and analysis. We then derive 3D-polar coordinate representations which satisfy the prerequisites, namely a space based on the norm which has efficient linear transform functions to and from the RGB space; and an improved HLS (IHLS) space. The most important property of this latter space is a “well-behaved” saturation coordinate which, in contrast to commonly used ones, always has a small numerical value for near-achromatic colours, and is completely independent of the brightness function. Three applications taking advantage of the good properties of the IHLS space are described: the calculation of a saturation-weighted hue mean and of saturation-weighted hue histograms, and feature extraction using mathematical morphology. 1Updated July 16, 2003. 2Jean Serra is with the Centre de Morphologie Mathématique, Ecole des Mines de Paris, 35 rue Saint-Honoré, 77305 Fontainebleau cedex, France.
منابع مشابه
Colour Image Analysis in 3D-Polar Coordinates
The use of 3D-polar coordinate representations of the RGB colour space is widespread, although many of these representations, such as HLS and HSV, have deficiencies rendering them unsuitable for quantitative image analysis. Three prerequisites for 3D-polar coordinate colour spaces which do not suffer from these deficiencies are suggested, and the results of the derivation of three colour spaces...
متن کاملCircular Statistics Applied to Colour Images
Three methods for summarising the characteristics of colour images are presented. They all rely on the ability to represent colours in terms of a 3D-polar coordinate system having independent brightness and saturation coordinates. The methods discussed are: hue statistics and saturation-weighted hue statistics, saturation-weighted hue histograms, and colour statistics histograms. The latter are...
متن کاملPhysics-based Segmentation of Colour Images in Spherical Coordinates
We present image segmentation and highlight detection algorithms based on the dichromatic reflection model. For image segmentation, we use the model prediction that objects of a certain colour produce lines (the matte lines) radiating away from the origin of the RGB colour space. These lines therefore show up as peaks in a 2-dimensional histogram of the angular coordinates of a spherical polar ...
متن کاملModelling and segmentation of colour images in polar representations
The suitability of polar representation for quantitative image processing tasks is investigated. The classical colour polar-based representations (HLS, HSV, etc.) lead to brightness and saturation with nonconsistent properties. After a short critical analysis of the gamma correction, a new polar representation using the L1 norm is proposed. It satisfies several quantitative requirements. The re...
متن کامل