Analysis of sharpness increase by image noise
Analysis of sharpness increase by image noise
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图像噪声引起的清晰度增加分析
DOI：
10.1117/12.806078
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发表时间：
2009
期刊：
影响因子：
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通讯作者：
Hiroyuki Kobayashi
中科院分区：
文献类型：
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作者：
T. Kurihara;N. Aoki;Hiroyuki Kobayashi
受图像噪声导致锐度增加的报道的启发，我们研究了噪声如何影响锐度感知。我们首先使用带有不同数量噪声的树皮自然图像，看看噪声是否会增强清晰度。虽然结果显示，随着噪声量的增加，清晰度下降，一些观察者似乎感知到更多的清晰度随着噪声的增加，而其他人没有。接下来，我们使用1D和2D单频模式作为刺激，试图减少这种变化的判断。结果表明，对于较高频率的刺激，锐度随着噪声量的增加而降低，而对于较低频率的刺激，锐度在一定的噪声水平下增加。从这个结果，我们认为图像噪声可能会降低边缘的清晰度，但能够提高图像中的低频分量或纹理的清晰度。为了证明这一预测，我们再次使用第一个实验中使用的自然图像进行实验。通过分别对图像的边缘或纹理部分施加噪声来产生刺激。实验结果表明，在边缘区域加入噪声，只会降低图像的清晰度，而在纹理区域加入噪声，则会提高图像的清晰度。我们认为正是噪声和纹理的相互作用使图像锐化。
Motivated by the reported increase in sharpness by image noise, we investigated how noise affects sharpness perception. We first used natural images of tree bark with different amounts of noise to see whether noise enhances sharpness. Although the result showed sharpness decreased as noise amount increased, some observers seemed to perceive more sharpness with increasing noise, while the others did not. We next used 1D and 2D uni-frequency patterns as stimuli in an attempt to reduce such variability in the judgment. The result showed, for higher frequency stimuli, sharpness decreased as the noise amount increased, while sharpness of the lower frequency stimuli increased at a certain noise level. From this result, we thought image noise might reduce sharpness at edges, but be able to improve sharpness of lower frequency component or texture in image. To prove this prediction, we experimented again with the natural image used in the first experiment. Stimuli were made by applying noise separately to edge or to texture part of the image. The result showed noise, when added to edge region, only decreased sharpness, whereas when added to texture, could improve sharpness. We think it is the interaction between noise and texture that sharpens image.