Signal correction device, image reading device, image processing apparatus, signal correction method, and computer program product

A signal correction method to be executed by a signal correction device, the method comprising:

• generating a correction signal serving to remove noise superimposed on an input signal;
• shifting a phase of the generated correction signal;
• generating an output signal for output by subtracting the correction signal from the input signal;
• detecting a peak value and a bottom value of the output signal;
• and
• determining an amount of phase shift from the detected peak value and bottom value of the output signal, wherein
• the determining comprises detecting uncorrected noise from the peak value and the bottom value of the output signal, and setting the amount of phase shift of the correction signal such that the uncorrected noise is reduced to a minimum, and
• the determining comprises:
• storing first uncorrected noise detected from the output signal corrected by the correction signal before the change of the amount of phase shift in a first storage;
• storing second uncorrected noise detected from the output signal corrected by the correction signal after the change of the amount of phase shift in a second storage;
• and
• comparing the first uncorrected noise stored in the first storage and the second uncorrected noise stored in the second storage using a comparator,
• wherein the comparator determines whether to change the amount of phase shift on the basis of a result of the comparison.

A computer program product comprising a non-transitory computer readable medium including programmed instructions, wherein the instructions, when are executed by a computer mounted on a signal correction device connectable to a server via a network, cause the computer to execute:

• generating a correction signal serving to remove noise superimposed on an input signal;
• shifting a phase of the generated correction signal;
• generating an output signal for output by subtracting the correction signal from the input signal;
• detecting a peak value and a bottom value of the output signal;
• and
• determining an amount of phase shift from the detected peak value and bottom value of the output signal, wherein
• the determining comprises detecting uncorrected noise from the peak value and the bottom value of the output signal, and setting the phase shift amount of the correction signal such that the uncorrected noise is reduced to a minimum, and
• the determining comprises:
• storing first uncorrected noise detected from the output signal corrected by the correction signal before the change of the amount of phase shift in a first storage;
• storing second uncorrected noise detected from the output signal corrected by the correction signal after the change of the amount of phase shift in a second storage;
• and
• comparing the first uncorrected noise stored in the first storage and the second uncorrected noise stored in the second storage using a comparator,
• wherein the comparator determines whether to change the amount of phase shift on the basis of a result of the comparison.