Apparatus and method for improving image quality in a image sensor

The invention proposes an apparatus and method for improving image quality for the images captured by the device for recording an image by using the CMOS image sensor. To this end the present invention, to adjust the black level for the captured image signal, and expand the brightness of the image signal can express through the knee correction on the image signal of which the black level adjustment. Also to be made prior to the interpolation of the gamma correction for the image signal to restore the defective pixel. CMOS image sensor, black level, knee correction, white balance, gamma correction