کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
4033752 | 1603203 | 2013 | 10 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Pooling of first-order inputs in second-order vision Pooling of first-order inputs in second-order vision](/preview/png/4033752.png)
• Standard 2nd-order vision model implies low 2nd-order high frequency sensitivity.
• Broadly tuned 1st-order channels improve high-frequency sensitivity.
• Cross-carrier adaptation study supports broadly tuned 1st-stage filters.
• Lowpass CSF at low 1st-order contrast suggests pooling standard 1st- order channels.
The processing of texture patterns has been characterized by a model that first filters the image to isolate one texture component, then applies a rectifying nonlinearity that converts texture variation into intensity variation, and finally processes the resulting pattern with mechanisms similar to those used in processing luminance-defined images (spatial-frequency- and orientation-tuned filters). This model, known as FRF for filter rectify filter, has the appeal of explaining sensitivity to second-order patterns in terms of mechanisms known to exist for processing first-order patterns. This model implies an unexpected interaction between the first and second stages of filtering; if the first-stage filter consists of narrowband mechanisms tuned to detect the carrier texture, then sensitivity to high-frequency texture modulations should be much lower than is observed in humans. We propose that the human visual system must pool over first-order channels tuned to a wide range of spatial frequencies and orientations to achieve texture demodulation, and provide psychophysical evidence for pooling in a cross-carrier adaptation experiment and in an experiment that measures modulation contrast sensitivity at very low first-order contrast.
Journal: Vision Research - Volume 91, 18 October 2013, Pages 108–117