| Summary: | 碩士 === 國立中山大學 === 機械與機電工程學系研究所 === 96 === “Mura” is a local lightness variation without a clear contour on a uniform surface image, which imparts an unpleasant sensation to human vision.
In this study, a Haar wavelet transform (WT) method is proposed to detect the mura of the polarizer. Because of the WT capability of multi-resolution analysis for digital images, the difference of gray level between neighbor pixels in different scale of an image can be analyzed by the WT high frequency coefficient. As a result, different size muras at different location can be segmented.
Because the Haar WT cannot extract all the high frequency coefficient from an image at one time, the original image is decomposed into an main image and a subimage at the beginning. The applying the WT technique to extract all the high frequency coefficients from these two images. There exist three types of mura consisting of line mura, band mura, and area mura. Experiments were extensively conducted on different frequencies and sizes of these muras. Experimental results show that the presented approach is able to detect all the line muras, but some band and area muras.
The result of this study can be extended to the future researches regarding mura properties and detection methods.
|
|---|
