Photographic equidensitometry of metaphase chromosomes

Summary Photographic equidensitometry, which is a procedure to obtain specific lines or symbols for points of equal optical density, has been utilized in the study of chromosome images. Equidensitometric techniques, using a special contour film, permitted three approaches, namely, production of line equidensities (in the form of families, sequences and contour maps), color equidensities (color conversion of line sequences), and screen equidensities (substituting characteristic symbols for densities). All these techniques have proved very useful to analyze images of metaphase chromosomes and occurrence of spontaneous banding patterns, by showing the precise distribution and relative values of the grey gradient. This report demonstrates the potential of photographic equidensitometrical procedures for chromosome studies, which obviates the need to purchase elaborate equipment.