Image signal processing unit for amplifying signal level of effective pixel region and method

An image signal processing unit for processing pixel signals provided by color pixels of an image device, each pixel signal including a color level signal and a black level signal superimposed on the color level signal, the processing unit comprising:

• a first amplifier to set a first amplification factor for the pixel signals for each color pixel to adjust the sensitivities of the color pixels;
• a second amplifier to amplify the pixel signals received from the first amplifier with a second amplification factor to increase a color level signal of the first adjusted pixel signals towards a maximum signal so as to have a signal intensity equivalent to a dynamic range of image processing performed in a latter stage;
• a computing unit to subtract a black level signal component, which is an analog signal, from each of the pixel signals, which are analog signals, amplified by the second amplifier and to output analog output signals;
• an A/D converter to convert the analog output signals into digital output Signals;
• a digital signal processor to process the digital output signals, and to determine a first value corresponding to the first amplification factor, a second value corresponding to the second amplification factor, and a third value corresponding to the black level signal;
• a D/A converter coupled to the computing unit;
• and
• a plurality of registers to store the first value, the second value, and the third value based on the digital signal processor, and to supply the first value to the first amplifier, to supply the second value to the second amplifier, and to supply the third value to the D/A converter,
• wherein the D/A converter converts the third value into the black level signal, and supplies the black level signal to the computing unit.