Abstract
We have studied a new metric for color image noise (graininess) evaluation that is also applied to monochrome images. Graininess would be the most important and basic attributes for pictorial images, and Graininess Scale (GS) has been widely used as a noise perception model. Similar to the treatment adopted in the GS, we have computed Lightness Noise (LN) by using the lightness instead of the reflection density and by using a new sensitivity function based on a model describing our observations. But LN would not be sufficient for chromatic images as it is. So, we focused our attention on the fluctuations of both chroma and hue-angle on color images as these decrease perceived color image quality. Chromatic Noise (CN) has computed by using these fluctuations with consideration to spatial filters by the human visual system. Finally, we have obtained Graininess Index (GI) by using both LN and CN. To confirm our approach, we made subjective assessments for test patches, and got good relationship (γ=0.91) between GI and subjective evaluated levels.
