Banding is a printer artifact perceived as one dimensional luminance variations across the print-out caused by the vibrations of different printer components. In the printing industry, banding is considered to be one of the worst defects that dominates overall perceived image quality. Understanding the visibility of banding will help us in developing strategies to reduce the banding artifact. We developed a softcopy environment to conduct various experiments for investigating the visibility of banding. This environment includes the methodology to duplicate the print on the monitor, and a banding extraction technique. This technique enables us to freely adjust the magnitude of banding of any printer. We validated the accuracy of this methodology by conducting a banding matching experiment. We used this platform to conduct banding visibility assessment experiments. One of them was a banding discrimination experiment. The results showed that
for the printers investigated, a reduction of 6.5% in the banding magnitude will be just noticeable by an average observer. We were also able to find the detection thresholds of banding in grayscale images for three laser electrophotographic printers. The detection threshold of the best printer was about 50% of its original banding. So there is still plenty of room to reduce the visibility of the banding artifact. We were also able to compare the banding visibility of different printers quantitatively by conducting a cross-platform experiment. This methodology can form the basis for a metric for visibility of banding.
We present a new CRT characterization technique that improves the accuracy of the characterization. This is achieved by optimizing the linear transformation matrix of the two stage model in the uniform CIE/L*a*b* space. We also introduce an approach to improve the characterization performance for low luminance colors. These methods are used to calibrate two CRT monitors and better accuracies are obtained compared to existing methods, especially for low luminance colors. We present a systematic way to adjust the white point of the monitor using hardware settings. This allows us to adjust the
monitor white accurately without losing any digital counts which is the case if a software approach is used. We propose a novel search algorithm to achieve very high accuracy calibration for experiments where a limited number of colors has to be displayed. We apply this search algorithm to the case of monochrome image display application and verify the performance our method.