Quick Guide to Precision Measuring Instruments

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PG48Difference in Image QualityDifference between 2-level and 256-level gray-scale imagesSample image displayed in 2-level gray scaleSample image displayed in 256-level gray scaleVariation in Image Depending on Threshold LevelThese three pictures are the same image displayed as 2-level gray scale at different slice levels (threshold levels). In a 2-level gray-scale image, different images are provided as shown above due to a difference in slice level. Therefore, the 2-level gray scale is not used for high-precision vision measurement since numeric values will change depending on the threshold level that is set.Vision Measuring MachinesGray ScaleA PC stores an image after internally converting it to numeric values. A numeric value is assigned to each pixel of an image. Image quality varies depending on how many levels of gray scale are dened by the numeric values. The PC provides two types of gray scale: two-level and multi-level. The pixels in an image are usually displayed as 256-level gray scale.Pixels in an image brighter than a given level are displayed as white and all other pixels are displayed as black.Each pixel is displayed as one of 256 levels between black and white. This allows high-delity images to be displayed.10 25512702-levelgray scale WhiteGrayBlackMulti-levelgray scale WhiteGrayBlack10 25512702-levelgray scale WhiteGrayBlackMulti-levelgray scale WhiteGrayBlack10 25512702-levelgray scale WhiteGrayBlackMulti-levelgray scale WhiteGrayBlack10 25512702-levelgray scale WhiteGrayBlackMulti-levelgray scale WhiteGrayBlack