and cy signals from the amplifiers 75 and 76 are added by the adder 83 the ye and g signals from the amplifiers 77 and 78 are added by the adder 84 the outputs from the adders 83 and 84 are subtracted by the subtracter 92 so that a b signal is produced the arithmetic expressions of the above r and b signals are shown in expressions 1 and 2 where w cy ye and g represent the signal amounts derived from the photo sensing elements corresponding to the respective color filters and are proportional to the sensitivity ratios of the respective photo sensing elements u03b1 u03b2 and u03b3 denote the arithmetic operational ratios when the r signal is calculated u03b1 39 u03b2 39 and u03b3 39 represent the arithmetic operational ratios when the b signal is calculated the arithmetic operational ratios are 1 when the w signal is calculated the magnitude m r of the r aliasing to be generated in the r signal when the r signal is produced by means of the operation shown in the expression 1 is expressed as follows in the expressions 3 to 5 the central coordinates on the spatial frequency at which the aliasings are generated are indicated in the parentheses fig4 shows the positions on the two dimensional spatial frequencies at which the aliasings are generated f s and f l denote sampling frequencies in the horizontal and vertical directions by the picture elements of the image pickup device respectively reference numeral 10 denotes aliasings in the r aliasings the aliasings shown in the expressions 3 and 4 are the aliasings which are caused by the sensitivity differences of the photo sensing elements corresponding to the respective color filters these aliasings.