Patent ID: 7672019

Claim:
An image scanning apparatus, comprising: three color line sensors for outputting red, green, and blue color signals, respectively; a monochrome line sensor for outputting a monochrome signal having a higher resolution than the color signals; and a resolution-enhancement processor for enhancing a resolution of a pixel signal of the color signals, based on a monochrome smoothed value obtained by smoothing a signal of an arbitrary pixel of the monochrome signal and signals of pixels around the arbitrary pixel and a color smoothed value obtained by smoothing a signal of a pixel of each color signal and signals of pixels around the pixel of the color signal, the pixel of the color signal corresponding to the position of the arbitrary pixel of the monochrome signal, wherein the resolution-enhancement processor determines a first monochrome smoothed value obtained by smoothing a signal of an arbitrary pixel of the monochrome signal and signals of a first area around the arbitrary pixel, a second monochrome smoothed value obtained by smoothing the signal of the arbitrary pixel of the monochrome signal and signals of a second area that is smaller than the first area, and a color smoothed value obtained by smoothing a signal of a pixel of the color signal and signals of the first area around the pixel of the color signal; the resolution-enhancement processor multiplies a value, obtained by subtracting the first monochrome smoothed value from the second monochrome smoothed value, by a first coefficient and then adds a resulting value to the determined color smoothed value to thereby determine an intermediate color value; and the resolution-enhancement processor multiplies a value, obtained by subtracting the second monochrome smoothed value from the signal of the arbitrary pixel of the monochrome signal, by a second coefficient and then adds a resulting value to the intermediate color value to thereby enhance the resolution of the pixel of the color signal.