Provided is a light source device including a plurality of light emitting points arranged in matrix within a first cross section parallel to a first direction and a second direction. When light emitting points are projected within a second cross section parallel to first direction and a third direction perpendicular to first cross section, light emitting points have equal intervals between projections adjacent to each other. When light emitting points are projected within a third cross section parallel to second and third directions, light emitting points have equal intervals between projections adjacent to each other. An interval between light emitting points adjacent to each other in a row of matrix, an interval between light emitting points adjacent to each other in a column of matrix, an angle between row and column, an angle between column and first direction, and an angle between row and second direction are appropriately set.

An image sensor unit includes: a linear light source that illuminates a document with a light; a first erecting equal-magnification lens array and a second erecting equal-magnification lens array arranged in the stated order away from the document so as to receive a light reflected from the document and form an erecting equal-magnification image; a slit provided on an intermediate imaging plane between the first erecting equal-magnification lens array and the second erecting equal-magnification lens array; a diffraction grating that disperses a light output from the second erecting equal-magnification lens array; and a linear image sensor that receives a light dispersed by the diffraction grating.

An image reading device includes (i) light guides extending in a main scanning direction and configured to emit light from a light source toward a reading target moving relatively in a sub-scanning direction, the light from the light source being projected into end surfaces of the light guides in the main scanning direction, (ii) an optical filter arranged between the light source and the end surfaces of the light guides and configured to block or attenuate light having a specific wavelength from the light from the light source, (iii) a lens body to focus reflected light reflected by the reading target onto a light receiver to convert the reflected light into an electrical signal, and (iv) a lens holder. The lens holder includes a first positioner for positioning the light guides and a second positioner for positioning the optical filter.

An image processing apparatus includes a light source, an image sensor, and an invisible component remover. The light source emits visible component light and invisible component light to a target object. The image sensor receives reflected light from the target object to detect a visible invisible mixture image including an invisible component and a visible component and an invisible image including an invisible component. The invisible component remover, based on the visible invisible mixture image and the invisible image which have been detected, removes the invisible component from the visible invisible mixture image to generate a visible image. The invisible component remover includes a removal calculator performing a removal calculation process of an invisible component with respect to the visible invisible mixture image, and a noise reducer performing a noise reduction process on at least one of images to be input to and output from the removal calculator.

In a line sensor including color filters that are periodically disposed in a light-receiving-element row, a problem called a mixture of colors occurs. A mixture of colors occurs when light that has been transmitted through a color filter differing from a color filter corresponding to a light receiving element is incident upon the light receiving element.

In a CMOS sensor 107 including a light-receiving-element row in which a plurality of photodiodes 1204 are disposed side by side in a main scanning direction and a plurality of color filters 1202 that are disposed in correspondence with the plurality of photodiodes 1204, the center of each color filter 1202 is displaced in a direction of the center of the light-receiving-element row from the center of the photodiode 1204 corresponding to the color filter.

An image reading device includes a reading unit that reads an image formed on a first surface of a medium; a support unit that supports the medium from a second surface opposite to the first surface; and a pressing unit that blows air from a first surface side so as to press a portion of the medium to be read by the reading unit against the support unit.

In a line sensor including color filters that are periodically disposed in a light-receiving-element row, a problem called a mixture of colors occurs. A mixture of colors occurs when light that has been transmitted through a color filter differing from a color filter corresponding to a light receiving element is incident upon the light receiving element. In a CMOS sensor 107 including a light-receiving-element row in which a plurality of photodiodes 1204 are disposed side by side in a main scanning direction and a plurality of color filters 1202 that are disposed in correspondence with the plurality of photodiodes 1204, the center of each color filter 1202 is displaced in a direction of the center of the light-receiving-element row from the center of the photodiode 1204 corresponding to the color filter.

An optical device includes: a lens member including a plurality of lenses arranged such that optical axes of the lenses are substantially parallel to one another; and a plurality of column parts that are each provided along the optical axis of each lens among the plurality of lenses and each allow light to pass through inside, each column part having an outer periphery through which light is less likely to pass from inside to outside the column part than through an end portion of the column part in a direction along the optical axis, the plurality of column parts being integrally formed and disposed to face the lens member.

An optical device includes: a lens member including a plurality of lenses arranged such that optical axes of the lenses are substantially parallel to one another; and a light-transmitting member including: at least one light-transmitting part that is disposed to face the lens member, positioned on the optical axis of some of the plurality of lenses, and transmits light; and a light-shielding part that is provided on a surface of the light-transmitting part and blocks passage of light.

An image reading device includes a reading unit that reads an image formed on a first surface of a medium; a support unit that supports the medium from a second surface opposite to the first surface; and a pressing unit that blows air from a first surface side so as to press a portion of the medium to be read by the reading unit against the support unit.