Measurement of muscle fibre diameter by computer-aided image analysis

We describe an experiment to measure widths of muscle fibres by four methods, one manual and three based on interactive computer graphics using an image analyser. In all cases the width is defined as the length of a line associated with the fibre. This line may be defined by the observer directly or deduced by the computer from the fibre outline defined by the observer. Interactive computer graphics allow the speed to be increased fivefold with no loss in reproducibility in return for a small investment in software development. The speed might be further increased, perhaps tenfold, by the use of computerized image analysis based on densitometry but the number of analyses required per annum is not sufficient to justify the larger investment in software development that this would entail. The cost might be further decreased by the use of a simpler computer system.