초록 ▼

A system and method of enhancing dynamic range in images is disclosed that increases the contrast in the resulting image without requiring an increase in the dynamic range of the analog-to-digital converter used to convert the analog image signals to digital information. The system and method disclo

A system and method of enhancing dynamic range in images is disclosed that increases the contrast in the resulting image without requiring an increase in the dynamic range of the analog-to-digital converter used to convert the analog image signals to digital information. The system and method disclosed achieve this advantageous result by providing per-pixel gain control circuitry and per-pixel gain selection circuitry. The analog image signal range is segmented into a number (N) of multiple levels, where N is selected to be the desired level of enhancement. Multiple analog gain (G1) levels and multiple digital gain (G2) levels are also provided. The analog gain (G1) is selected for each image pixel based upon the segment in which that pixel falls so that the signal levels may be increased for each segment to utilize the full range (R) of the analog-to-digital converter. Once digitized, a digital gain (G2) is selected for the same pixel so that on a per-pixel basis, the total gain (G1*G2) is kept substantially constant. In this way, the dynamic range of the system is increased without needing to increase the dynamic range of the ADC. The resulting digital information is enhanced by (Log.sub.2 N) bits, and it may be companded down into a smaller bit range for a video output device by any desired transfer function during digital signal processing.

대표청구항 ▼

[ What is claimed is:] [1.] A per-pixel gain control system for image processing, comprising:a multiple level segment selector receiving pixel analog signals and having an output signal indicative of a segment within which each pixel falls on a per-pixel basis;an analog gain block receiving pixel an

[ What is claimed is:] [1.] A per-pixel gain control system for image processing, comprising:a multiple level segment selector receiving pixel analog signals and having an output signal indicative of a segment within which each pixel falls on a per-pixel basis;an analog gain block receiving pixel analog signals and having multiple selectable gain (G1) levels;an analog-to-digital converter receiving amplified analog signals from said analog gain block;a digital gain block receiving digitized data from said analog-to-digital converter and having multiple selectable gain (G2) levels; anda gain selector receiving said output signal from said multiple level segment selector and having gain select output signals applied to said analog gain block and said digital gain block on a per-pixel basis;wherein a combined per-pixel gain of said analog gain (G1) and said digital gain (G2) is substantially constant; andwherein said combined per-pixel gain is substantially equal to the number of levels (N) of said multiple level segment selector.