1. A solid-state image sensor, comprising: a plurality of pixels which are formed in matrix form on a semiconductor substrate, each pixel having a photoelectric converting element which outputs an electric signal obtained by photoelectric conversion; a read-out circuit configured to read out the electric signals outputted from the plurality of pixels; and a signal processing section configured to perform signal processing with respect to the electric signals read out from the read-out circuit, wherein the plurality of pixels includes: a plurality of first pixels which leads incident light of a visible light wavelength band to a corresponding photoelectric conversion element via a transparent layer; a plurality of second pixels, each having a first color filter having a higher transmissivity in a first visible light wavelength band within the visible light wavelength band, as compared to a transmissivity in a first remaining portion of the visible light wavelength band outside the first visible wavelength band; a plurality of third pixels, each having a second color filter having a higher transmissivity in a second visible light wavelength band, different from the first visible light wavelength band, within the visible light wavelength band, as compared to a transmissivity in a second remaining portion of the visible light wavelength band outside the second visible wavelength band; and a plurality of fourth pixels, each having a third color filter having a higher transmissivity in a third visible light wavelength band, different from the first and second visible light wavelength bands, within the visible light wavelength band, as compared to a third remaining portion of the visible light wavelength band outside the third visible wavelength band, wherein the signal processing section includes: a color acquisition section configured to acquire a first color data value C 1 , a second color data value C 2 , a third color data value C 3 and a white color data value W in a target pixel block including a plurality of pixels to perform signal process; a color separation processing section configured to separate the white data value into a plurality of colors based on the following Expressions (2) to (4) to generate the first color data value C 1 w of a first color, the second color data value C 2 w of a second color and the third color data value C 3 w of a third color; 
 C 1 W ←W·K 1 (2) 
 C 2 W← W·K 2 (3) 
 C 3 W← W·K 3 (4) where K 1 , K 2 , and K 3 indicate color ratios, and are determined by the color data values C 1 , C 2 and C 3 .