A combined imaging and spectral measurement line-scan imaging sensor includes a plurality of pixel lines. Each pixel line includes a plurality of pixels. At least one of the pixel lines is an imaging line designated for acquiring at least one image of an object and other of the pixel lines are spectral measurement lines designated for acquiring a spectral measurement of light received from the object. Each imaging line is associated with a single respective spectral response within a spectral range. Each pixel in each spectral measurement line is associated with a respective spectral band. Each of at least three pixels in each of the spectral measurement lines is respectively associated with different respective pixel spectral bands. The different respective pixel spectral bands are non-identical to any one of the single spectral responses associated with each of the imaging spectral lines.

An original image is read as an aggregate of a plurality of pixels in which adjacent pixels have different colors (R, G, and B) in a main scanning direction and in a sub-scanning direction, and the read pixels of the respective colors are stored in a line memory in association with information on relative positions of the pixels with respect to another pixel. Then, the stored pixels are sorted so that pixels having the same color are adjacent to each other, and an abnormal pixel (dust) not present in the original image is detected based on the state of the sorted pixels. With this, the dust not present in the original image is detected without increasing the cost, and the dust is corrected without forming a conspicuous trace of correction.

A solid-state image sensor includes a first color filter and a second color filter having different thicknesses and configured to transmit light in predetermined wavelength regions, light-receiving devices configured to receive the light in the predetermined wavelength regions passing through the first color filter and the second color filter, and a light amount compensator configured to compensate for an amount of the light passing through the first color filter or the second color filter.

An original image is read as an aggregate of a plurality of pixels in which adjacent pixels have different colors (R, G, and B) in a main scanning direction and in a sub-scanning direction, and the read pixels of the respective colors are stored in a line memory in association with information on relative positions of the pixels with respect to another pixel. Then, the stored pixels are sorted so that pixels having the same color are adjacent to each other, and an abnormal pixel (dust) not present in the original image is detected based on the state of the sorted pixels. With this, the dust not present in the original image is detected without increasing the cost, and the dust is corrected without forming a conspicuous trace of correction.

A sensor array assembly including a first sensor array, a second sensor array and a mounting substrate. The first sensor array includes a first process direction width and a first photosite, while the second sensor array includes a second process direction width and a second photosite. The first and second sensor arrays are separately secured on the mounting substrate. The first photosite is in precision alignment with the second photosite.

An image forming apparatus includes an optical sensor configured to detect reflected light from a detection image formed on the transfer member. The optical sensor includes a light emitting element configured to emit light for irradiating the detection image at a predetermined angle of incidence, a first light receiving element arranged at a position at which diffused reflected light from the detection image is received at a first angle of reflection, and a second light receiving element arranged at a position at which the diffused reflected light from the detection image is received at a second angle of reflection.

An image forming apparatus includes an optical sensor configured to detect reflected light from a detection image formed on the transfer member. The optical sensor includes a light emitting element configured to emit light for irradiating the detection image at a predetermined angle of incidence, a first light receiving element arranged at a position at which diffused reflected light from the detection image is received at a first angle of reflection, and a second light receiving element arranged at a position at which the diffused reflected light from the detection image is received at a second angle of reflection.

A sensor array assembly including a first sensor array, a second sensor array and a mounting substrate. The first sensor array includes a first process direction width and a first photosite, while the second sensor array includes a second process direction width and a second photosite. The first and second sensor arrays are separately secured on the mounting substrate. The first photosite is in precision alignment with the second photosite.

By overlapping lighting timings of light sources that emit lights of a plurality of different wavelength bands including a wavelength band of at least a visible light region and an infrared light region, the lights of the plurality of the different wavelength bands including the wavelength band of at least the visible light region and the infrared light region are emitted on a banknote while securing an overlap in timings thereof. Moreover, by using light receiving elements each including a bandpass filter that allows only light of a wavelength range that corresponds to the wavelength band of each of the light sources, received light intensities of the light of the wavelength range that corresponds to the wavelength band of each of the light sources are acquired simultaneously, and image data are formed based on the received light intensity of every acquired wavelength band.

An image scanner is configured to: while changing a reading position by a position changer and sequentially emitting light of each of three colors in a turn-on sequence from a light source to a document, control a line sensor to read reflection light of emitted light, thereby acquiring gradation image data including gradation values of three colors for each pixel in one line; determine whether a top color shift occurs in the gradation image data at a determination position; in response to determining that the top color shift occurs at the determination position, replace gradation image data at the determination position with black image data; determine whether a bottom color shift occurs in the gradation image data at the determination position; and in response to determining that the bottom color shift occurs at the determination position, replace gradation image data at the determination position with white image data.