CHAPTER 3 IMAGE READING/PROCESSING SYSTEMCOPYRIGHT © 2002 CANON INC. 2000 CANON iR1600/iR2000/iR1610/iR2010 SERIES REV.0 MAR. 20023-124.4.1 Black Shading CorrectionThe input signal of the CS while the LEDs are kept OFF is read, and is subjected to A/Dconversion (black correction), storing the result (digital signal) in memory.When an image is read, the black correction value is subtracted from the value of theimage signal read by each pixel of the CS by way of full pixel black shading correction.4.4.2 White Shading CorrectionThe light of the LEDs is directed against the standard white plate, and the CS input sig-nal is read. The result is subjected to A/D conversion (white correction), storing the result(digital signal) in memory.The image data to which black shading correction was executed is then subjected tocomputation using the white correction value, thus executing full pixel white shading cor-rection. As a result, the variation in LED intensify and in the intensity of the rod lens ar-ray are corrected, evening out the image density level.Shading correction is executed as follows:· When the Start key is pressed.The image data after shading correction is converted from 10-bit into 8-bit data.4.5 Re-OrderingThe input signals from the CS consist of image data read simultaneously by each of the4 systems of CCD device units; thus, they are not in the same sequence as the signals thatrepresent the original image, re-ordering.F03-405-01a 2a 1 , ..... b 2b 1 , ..... c 2c 1 , ..... d 2d 1 , .....a 1 ..........b 1 c 1 d 1 a 2 b 2 c 2a 1 ....... ...........a 2 a 3 b 1 b 2OS1 OS2 OS3 OS4CS unitRead imagedataData items ofcorrect order(original image data)Re-ordering
