Verbaken J H, Jacobs R J
Ophthalmic Physiol Opt. 1985;5(4):459-65.
Whilst most optometrists today are aware of the need for a practical method of measuring the contrast sensitivity function (CSF), cost and length of testing have usually precluded this measurement. As the Arden Grating Test is a screening test for normal CSF, and since many patients with low vision cannot see any of its gratings, there is a need for a test with an extended contrast range which is calibrated to allow quantitative measurement of contrast thresholds in the clinic. This paper discusses the problems associated with the use of the photographic process to manufacture such a test. A series of stimuli covering a wide range of contrasts were manufactured photographically and evaluated photometrically and psychophysically to validate the photographic process. The results show that the photographic techniques can be controlled sufficiently to enable the manufacture of stimuli of the required contrasts and that, at low contrasts where calibration is inaccurate or impossible, the contrasts produced are linearly related to exposure. The results also show that the illumination and observation conditions need to be accurately controlled for the plate contrast to be unaffected by veiling glare.
虽然如今大多数验光师都意识到需要一种实用的方法来测量对比敏感度函数（CSF），但测试成本和时长通常使这种测量无法实现。由于阿登光栅测试是对正常CSF的筛查测试，而且许多低视力患者看不到其任何光栅，因此需要一种具有扩展对比度范围的测试，该测试经过校准，以便在临床中对对比阈值进行定量测量。本文讨论了使用照相工艺制作此类测试所涉及的问题。通过照相制作了一系列涵盖广泛对比度的刺激物，并进行了光度测量和心理物理学评估，以验证照相工艺。结果表明，照相技术能够得到充分控制，从而制造出所需对比度的刺激物，并且在低对比度情况下，校准不准确或无法校准时，所产生的对比度与曝光呈线性关系。结果还表明，为使平板对比度不受杂散光影响，需要精确控制照明和观察条件。
