Dimensional Measurement Variation of Scanned Objects Using Flatbed Scanners

摘要

This paper presents a study of the variations in the measured dimensions of objects obtained from their flatbed scanned images. Flatbed scanners have been used by other researchers to measure the dimensions of a wide variety of objects. While there is published research that considers scanner measurement variation, they lack detail on quantifying the effect of several sources of this variation. This paper investigates the effect of the object’s position relative to the scanner plate and the effect of scanning resolution on measurement. The object scanned was a high precision glass scale with photo etched graduations. A computer algorithm was developed to automatically measure the distances between the one millimeter spaced graduations on the glass scale based on its scanned images. Results showed that the measured spacing of the graduations varied in patterns depending on the position of the glass scale relative to the scanner and the scanning direction. However, there was not a clear pattern in the measured spacing as a function of scanning resolution even though the probability of detecting the graduations decreased with decreasing resolution. It was concluded that flatbed scanners can measure objects with sufficient accuracy and precision if the sources of measurement variation are quantified and minimized.