Quantitative characterization of muscle fiber by image analysis

Abstract

The paper describes a method for measuring a set of quantitative parameters — structural parameters (area, perimeter, diameters, shape factors) and parameters depending on gray-levels (average luminance and fiber type) in muscle fiber sections. Analysis is performed on a set of serially cut, transverse sections, obtained after a biopsy. A field selected on a serial cutting set is numerized with a CCD black and white video camera. It produces a set of monochrome digital images which are the input data for a model. The method first delineates each fiber section on the image called the reference cutting, calculates the structural parameters and then attempts to follow them on the other images of the set to integrate the other desired parameters, i.e., those depending on gray-levels. The method is semi-automatic. The two main steps (fiber section extraction and fiber section following) are designed to be used on the same principle: first, a completely automatic result is computed using appropriate digital image processing; second, this result is presented to the operator in order to be interactively validated. The software called RACINE (which implements the method) has been used successfully for several years by different laboratories of the French National Institute of Agronomic Research (INRA) on several kinds of animal muscles — pork, chicken, trout, beef, rabbit, mutton and turkey. The method allows measurements at fibre section scale on samples as large as several thousand fibres, providing improvements in speed, accuracy and statistical reliability of analyses. The main applications concern meat quality control during livestock production and genetic selection.