Quantitative densitometry of autoradiograms: digital images representative of optical density

Abstract

Microcomputer software has been developed to control video acquisition of 1024 x 1024 digital autoradiogram images which represent true optical density (OD). Since video cameras are sensitive to intensity (I), background correction and conversion to OD must be accomplished in software. The software linearizes camera output against an optical step tablet of known ODs and creates a 'look-up table' through which captured images are passed. This procedure allows the accurate and rapid conversion of a large number of images. The user is directed through the calibration and capture procedures; safeguards are included to ensure that the resultant images are correctly calibrated. The algorithms used in these programs accommodate the limited computing power available in microcomputers. The use of a commercially available graphics library will enhance the portability to multiple hardware configurations. This software is a low-cost alternative for the capture of digital images needed for quantitative densitometry.