apparatus in the second embodiment is the same as a respective one of the portions 1 2 3 4 and 6 in the first embodiment shown in fig3 the black shading correction portion 25 includes an average calculating circuit 17 which calculates the average dopb of the outputs of the ccd portion 1 obtained via the signal processing portion 2 and a d converting portion 3 during the period during which the ccd portion 1 obtains data through the photoelectric sensors of the above mentioned opb portion of the ccd a moving average circuit 29 which performs moving averaging using values outputted from the average calculating circuit 17 and a subtracter 18 which subtracts the moving average db thus calculated by the moving average circuit 19 from the data d 0 of the image signal outputted from the a d converting circuit 3 when the original image is read in fig5 the analog image signal outputted by the ccd portion 1 undergoes signal processing by the signal processing portion 2 and then is converted into the digital image signal by the a d converting portion 3 the digital image signal outputted from the a d converting portion 3 is inputted to the black shading correction portion 25 undergoes the black shading correction therethrough and then is outputted the image signal outputted from the black shading correction portion 25 is inputted to the white shading correction portion 6 the white shading correction portion 6 performs the white shading correction of the data of the thus inputted image signal using the white reference data which was.