Abstract: The tonal resolution of an image scanner is improved by adjusting the dynamic range of an analog-to-digital converter of the scanner. A preview scan of the image is made. The image data from the preview scan is then analyzed to determine a maximum intensity and a minimum intensity. The value of the maximum intensity is used to set a white intercept of the image scanner such that a maximum digital value of the analog-to-digital converter corresponds to the maximum intensity present in the image data from the preview scan. The minimum intensity is used to set a black intercept of the image scanner such that the minimum intensity in the image data from the preview scan corresponds to the minimum digital number output by the analog-to-digital converter. Tonal resolution of the image scanner is optimized then by performing a final scan of the image with the analog-to-digital converter programmed to reflect the new white intercept and black intercept values.

Abstract: An image capture system comprising a scanner having a 10-bit analog-to-digital converter. The scanner operates within an environment that includes a host computer that is configured to accept 8-bit data. The contrast enhancement of the scanner is improved by applying an improved tonal adjustment on a scanned image. The host computer connected to the scanner provides an 256-value to 256-value look-up table (i.e., the 8-bit tone map) to the scanner. The scanner generates an interpolated 1024-level to 256-level look-up table (i.e., a 10-bit tone map) from the 256-level to 256-level look-up table. The 1024-value to 256-value look-up table is generated by using linear interpolation and extrapolation. The scanner can thus provide better contrast enhancements without having to modify the software running on the host computer.

Abstract: A method for dynamically determining and adjusting the color balance of the light strip along one edge of the scanned area and adjusting the gains of independently controlled red, green and blue channels of a CCD array. Alternatively, the gain of one color channel may be held constant and measured to determine the light intensity of the light source as the temperature of the light source varies. The power to the light is then changed to maintain the intensity of the light source within a predetermined range. The three color channels are then compared to a predetermined color balance. If the color balance is outside of a predetermined range, the other two color channels gains are varied in order to maintain the color balance between the three color channels.