Mark E. Shafer

Design And Performance Of A CCD High-Resolution 35 mm Film Scanner

A color scanner producing high-resolution digital image data, 4096 x 6144 pixels per color from 35 mm color negative film, has been developed. A linear charge-coupled device (CCD) image sensor and mechanical translation are utilized to achieve 4425 lines per inch sampling pitch. Red, green and blue fields are scanned sequentially, each in 34 seconds. At 1.0 megapixel/second, the measured data are digitally processed to remove individual photosite variations and are transformed to log space. The processing also includes data averaging; this option provides lower spatial resolution data at higher signal-to-noise ratios. Voltage signal-to-noise ratios of 2400:1, or 67 dB, have been achieved at the highest resolution. This paper discusses the design and performance of the scanner. Measured versus computed spatial frequency response is presented. The hardware processing is described. A model for processing computational error analysis is presented along with noise measurements. Finally, special film considerations are discussed.