A Two-dimensional Adjustment Tool for Color Image Enhancement

摘要

One- and two-dimensional adjustment tools were tested to find ways to make the enhancement of photographic color images as easy and quickly as possible. Visually assessed image quality was defined as a function of two global image properties for various test images. The emphasis was on the brightness/contrast combination. Results showed that the location of the maximum and the shape of these (two-dimensional) quality functions varied considerably from image to image. Moreover, in many cases it proved to be difficult to attain optimum quality when image properties were adjusted separately. Often several additional iteration rounds (i.e. repetitive back and forth movement of the two sliders) were needed. To avoid this, a two-dimensional adjustment tool was developed. This tool gives the user real-time visual feedback and an opportunity to adjust two selected variables simultaneously simply by using a mouse to move a cursor on a two-dimensional plane. Two-dimensional image adjustment proved to be more efficient (i.e. faster) than two one-dimensional adjustments. Tests with brightness/contrast adjustment showed that 2-D adjustment is much quicker when the original adjustment variables are far from their optimum values and when the test person is well-trained. If the person is not well-trained, two-dimensional adjustment should be combined with automatic guidance.