Abstract
Purpose: Can reduced brightness of natural images be compensated by increasing luminance contrast?
Method: Four human subjects were asked to match the brightness of complex stimuli by adjusting luminance contrast in a dark surround. Method of adjust was used to find the point of subjective isoluminance across 60% to 150% of brightness. A sigmoidal function was used to modulate the luminance contrast of natural images.
Results: Consistent results for 70% to 110% of brightness were found among the four subjects. In this range, the luminance contrast is an inverse linear function of brightness with virtually identical constants for the four subjects. Beyond this range, however, the matching became difficult and led to diverse results.
Conclusion: This finding can be applied to display design. For example, increasing contrast can enhance image quality when the luminance is reduced to save power consumption of portable electronic devices. The high-dynamic range algorithms can also employ this finding to increase the apparent contrast of natural images.