MODELING THE DEPENDENCE OF CONTRAST SENSITIVITY ON GRATING AREA AND SPATIAL-FREQUENCY
MODELING THE DEPENDENCE OF CONTRAST SENSITIVITY ON GRATING AREA AND SPATIAL-FREQUENCY
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DOI：
10.1016/0042-6989(93)90235-o
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发表时间：
1993-12-01
期刊：
影响因子：
1.8
通讯作者：
NASANEN, R
中科院分区：
文献类型：
--
作者：
ROVAMO, J;LUNTINEN, O;NASANEN, R
我们在检测任务中将人类中央凹视觉系统建模为简单的图像处理器，其包括（i）由于眼睛的光学传递函数而进行的低通滤波，（ii）神经源的高通滤波，（iii）添加内部神经噪声，以及（iv）通过局部匹配滤波器进行检测。它的检测效率的光栅是恒定的，直到一个临界面积，但随着面积的增加而下降。为了测试模型，我们测量了迈克尔逊对比灵敏度作为光栅面积的函数，在空间频率为0.125-32 c/deg的简单的垂直和圆形余弦光栅。在圆形光栅中，亮度作为光栅场半径的函数被正弦调制。在协议的模型，在所有的空间频率的对比灵敏度增加成比例的平方根的光栅面积在小面积。当光栅面积超过临界面积时，在大的光栅面积处，增加饱和，对比灵敏度变得与面积无关。因此，在小的光栅区域，空间积分服从Piper定律。空间整合的临界区域，标志着派珀定律的终止，在低空间频率下的立体度是恒定的，但在中等和高空间频率下与空间频率的平方成反比。在低空间频率下，通过空间积分可获得的最大对比灵敏度与空间频率成比例地增加，但在高空间频率下，其与增加的空间频率的立方成比例地降低。增加是由于神经源的高通滤波（侧抑制），减少主要是由于眼睛的光学传递函数。我们的模型解释了对比敏感度数据总方差的95%。
We modelled the human foveal visual system in a detection task as a simple image processor comprising (i) low-pass filtering due to the optical transfer function of the eye, (ii) high-pass filtering of neural origin, (iii) addition of internal neural noise, and (iv) detection by a local matched filter. Its detection efficiency for gratings was constant up to a critical area but then decreased with increasing area. To test the model we measured Michelson contrast sensitivity as a function of grating area at spatial frequencies of 0.125-32 c/deg for simple vertical and circular cosine gratings. In circular gratings luminance was sinusoidally modulated as a function of the radius of the grating field. In agreement with the model, contrast sensitivity at all spatial frequencies increased in proportion to the square-root of grating area at small areas. When grating area exceeded critical area, the increase saturated and contrast sensitivity became independent of area at large grating areas. Spatial integration thus obeyed Piper's law at small grating areas. The critical area of spatial integration, marking the cessation of Piper's law, was constant in solid degrees at low spatial frequencies but inversely proportional to spatial frequency squared at medium and high spatial frequencies. At low spatial frequencies the maximum contrast sensitivity obtainable by spatial integration increased in proportion to spatial frequency but at high spatial frequencies it decreased in proportion to the cube of the increasing spatial frequency. The increase was due to high-pass filtering of neural origin (lateral inhibition) and the decrease was mainly due to the optical transfer function of the eye. Our model explained 95% of the total variance of the contrast sensitivity data.