DIGITAL PROCESSING METHOD
There are numerous types of known surface defects that might occur
on the copper plate of an optical disc namely: water break, spotting
out, scratching, pitting , smut and etc. The gray
images of a optical disc microstructure are obtained from a CCD camera.
We can determine the difference of gray level in defected and non-defected
areas by analyzing and comparing the gray images of effected plates. The
results obtained provide an easy and effective method to detect defects.
One proceed with a series of digital image processing techniques namely
filtering, inverse, Laplican, scaling, normalized and binary operations.
According to the binary image version a computer programmer could easily
develop programs to distinguish the defected images from the non-defected
images by gray level discrepancy. Fig.2 highlights the (a) original defected
image (b) the binary image and (c) pixelized image. But the further classification
of defects on an optical disc is very time consuming, so a neural network
operation is needed.
(a) original defect image (b) binary image
(c) pixelized image
Fig. 2 image processing
For example, Here we show how to identify the defects of water break.
A modified recognition neural network is applied. The algorithm and network
topology are described below. First, we introduce the network architecture.
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