Automated segment-based visual enhancement of photographs
Saumil A. Bhukhanwala, Tenkasi V. Ramabadran · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 1993
In this paper we describe an automated method for the enhancement of digital photographic images. The enhancement incorporates the basic photographic principle that films have best detail in mid-tones and suppressed detail toward the extremes. This means that the subject or the visually strong areas must comprise of mid-tones in order to have good detail. Hence appropriate regions of visual significance within an image are first identified based on the features of focus, contrast, and texture. Enhancement of the image then follows by a gray level transformation of different pixels using a simulated exposure-density curve of photographic films. The enhancement is influenced strongly by the visually significant areas rather than the entire image (global statistics). This allows the subject or important areas to be enhanced to an optimum level (mid-tones) rather than achieving good overall balance but with a dull (over-exposed or underexposed) subject.