| 摘要 |
A method for measuring a halftone dot area rate, i.e. a halftone picture density, in a densitometer or halftone dot area rate measuring means. A light beam is emitted by a light source and impinges upon an object to be measured. The light beam passes through or is reflected from the object to be measured and is received by a photoelectric element. An aperture diameter is selected such that, when the halftone dot area rate in a reference surface which has a screen pitch equal to that of the measured surface is approximately 50%, the ratio of the area of the dark portions to the area of the light portions of the halftone dots included within the aperture diameter, i.e. the measured surface, is substantially 1:1.
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