Instituto Óptica, Consejo Superior de Investigaciones Científicas-CSIC, Madrid, Spain.
PLoS One. 2013 Aug 14;8(8):e70856. doi: 10.1371/journal.pone.0070856. eCollection 2013.
The image formed by the eye's optics is blurred by the ocular aberrations, specific to each eye. Recent studies demonstrated that the eye is adapted to the level of blur produced by the high order aberrations (HOA). We examined whether visual coding is also adapted to the orientation of the natural HOA of the eye.
Judgments of perceived blur were measured in 5 subjects in a psychophysical procedure inspired by the "Classification Images" technique. Subjects were presented 500 pairs of images, artificially blurred with HOA from 100 real eyes (i.e. different orientations), with total blur level adjusted to match the subject's natural blur. Subjects selected the image that appeared best focused in each random pair, in a 6-choice ranked response. Images were presented through Adaptive Optics correction of the subject's aberrations. The images selected as best focused were identified as positive, the other as negative responses. The highest classified positive responses correlated more with the subject's Point Spread Function, PSF, (r = 0.47 on average) than the negative (r = 0.34) and the difference was significant for all subjects (p<0.02). Using the orientation of the best fitting ellipse of angularly averaged integrated PSF intensities (weighted by the subject's responses) we found that in 4 subjects the positive PSF response was close to the subject's natural PSF orientation (within 21 degrees on average) whereas the negative PSF response was almost perpendicularly oriented to the natural PSF (at 76 degrees on average).
The Classification-Images inspired method is very powerful in identifying the internally coded blur of subjects. The consistent bias of the Positive PSFs towards the natural PSF in most subjects indicates that the internal code of blur appears rather specific to each subject's high order aberrations and reveals that the calibration mechanisms for normalizing blur also operate using orientation cues.
眼睛的光学系统形成的图像会因每个眼睛特有的眼像差而变得模糊。最近的研究表明，眼睛适应于由高阶像差（HOA）产生的模糊程度。我们研究了视觉编码是否也适应于眼睛的自然 HOA 的方向。
在受“分类图像”技术启发的心理物理程序中，我们在 5 名受试者中测量了感知模糊的判断。受试者呈现了 500 对图像，这些图像通过 100 只真实眼睛（即不同的方向）的 HOA 人为地模糊化，总模糊程度调整为与受试者的自然模糊相匹配。受试者在随机对中选择每个图像中看起来最聚焦的图像，在 6 个选择的排序响应中进行选择。图像通过对受试者的像差进行自适应光学校正来呈现。被选为最佳聚焦的图像被确定为阳性反应，其他为阴性反应。最高分类的阳性反应与受试者的点扩散函数（PSF）相关性更高（平均为 0.47），而与阴性反应（平均为 0.34）的相关性较低，并且所有受试者的差异均显著（p<0.02）。使用角平均积分 PSF 强度的最佳拟合椭圆的方向（由受试者的响应加权），我们发现，在 4 名受试者中，阳性 PSF 反应接近受试者的自然 PSF 方向（平均在 21 度以内），而阴性 PSF 反应几乎垂直于自然 PSF（平均在 76 度）。
受分类图像启发的方法在识别受试者内部编码的模糊方面非常有效。大多数受试者的阳性 PSF 偏向于自然 PSF 的一致偏差表明，模糊的内部代码似乎特定于每个受试者的高阶像差，并且揭示了用于标准化模糊的校准机制也使用方向线索进行操作。
