An image signal processing device includes a reference signal generating portion, a determination portion, and an extraction portion. The reference signal generating portion generates and outputs a reference signal that sequentially transmits reference pulses shifted from horizontal synchronization pulses on a horizontal synchronization signal by a predetermined shift time. The determination portion determines whether the horizontal synchronization pulses are normal by comparing time differences between input of the horizontal synchronization pulses and input of the reference pulses with the shift time. The extraction portion extracts line image data points from an image signal in synchronization with the input of the horizontal synchronization pulses that have been determined as normal.

An image signal processing device includes a reference signal generating portion, a determination portion, and an extraction portion. The reference signal generating portion generates and outputs a reference signal that sequentially transmits reference pulses shifted from horizontal synchronization pulses on a horizontal synchronization signal by a predetermined shift time. The determination portion determines whether the horizontal synchronization pulses are normal by comparing time differences between input of the horizontal synchronization pulses and input of the reference pulses with the shift time. The extraction portion extracts line image data points from an image signal in synchronization with the input of the horizontal synchronization pulses that have been determined as normal.

In a case where it is determined that image processing on image data is executed not in parallel with other image processing different from the image processing and printing of an image of the document is started after reading of an image of a first page of the document is completed, a transfer rate of image data from an image reading unit to an image processing unit is set to a predetermined transfer rate. Whereas in a case where it is determined that the image processing on image data is executed not in parallel with the other image processing different from the image processing and printing of the image of the document is started without waiting for the reading of the image of the first page of the document to be completed, the transfer rate is set to a transfer rate lower than the predetermined transfer rate.

A reading device includes a first light source configured to emit light, a second light source configured to emit light in a wavelength of light different from a wavelength of light of the first light source, circuitry configured to instruct the first light source and the second light source to turn on and turn off, a first light-intensity adjuster configured to adjust light intensity of the first light source based on a first light intensity value, a second light-intensity adjuster configured to adjust light intensity of the second light source based on a second light intensity value, a first image sensor configured to receive the light that is emitted from the first light source and is reflected by an object, and a second image sensor configured to receive the light that is emitted from the first light source and the second light source and is reflected by the object.

A reading device includes a first light source configured to emit light, a second light source configured to emit light in a wavelength of light different from a wavelength of light of the first light source, circuitry configured to instruct the first light source and the second light source to turn on and turn off, a first light-intensity adjuster configured to adjust light intensity of the first light source based on a first light intensity value, a second light-intensity adjuster configured to adjust light intensity of the second light source based on a second light intensity value, a first image sensor configured to receive the light that is emitted from the first light source and is reflected by an object, and a second image sensor configured to receive the light that is emitted from the first light source and the second light source and is reflected by the object.

An image processing apparatus that executes jobs in parallel using a small number of resources. A controller includes an image processor that applies an image process to image data. A scanner controller includes storage for storing image data generated by scanning a document with a scanner and transfers the image data stored to the controller through a data bus. A processor executes instructions to set a frequency of an image transfer clock to a first frequency when a first job including a process that transfers image data generated by scanning documents to the controller is executed alone, and set the frequency of the image transfer clock to a second frequency lower than the first frequency when the first job is executed in parallel to a second job including an image process. The frequency of the image transfer clock is maintained at the second frequency until finishing the first job.

Provided is a signal processing circuit including: a first terminal to which a control signal including identifier information indicating a control target is input; a determination circuit configured to determine the control target based on the identifier information; and a second terminal that is different from the first terminal. When the determination circuit determines that the control target is the signal processing circuit, the signal processing circuit performs a process in accordance with the control signal. When the determination circuit does not determine that the control target is the signal processing circuit, the signal processing circuit outputs the control signal from the second terminal.

An image processing apparatus that executes jobs in parallel using a small number of resources. A controller includes an image processor that applies an image process to image data. A scanner controller includes storage for storing image data generated by scanning a document with a scanner and transfers the image data stored to the controller through a data bus. A processor executes instructions to set a frequency of an image transfer clock to a first frequency when a first job including a process that transfers image data generated by scanning documents to the controller is executed alone, and set the frequency of the image transfer clock to a second frequency lower than the first frequency when the first job is executed in parallel to a second job including an image process. The frequency of the image transfer clock is maintained at the second frequency until finishing the first job.

An example image scanning apparatus includes a lighting unit to irradiate light onto a manuscript using an LED light source, a scan unit to generate a scan image by scanning image information of manuscript using light reflected by the manuscript, and a processor to control the lighting unit to irradiate light on each unit pixel by a predetermined duty during a movement process of the manuscript in a sub-scan direction.

Provided is a signal processing circuit including: a first terminal to which a control signal including identifier information indicating a control target is input; a determination circuit configured to determine the control target based on the identifier information; and a second terminal that is different from the first terminal. When the determination circuit determines that the control target is the signal processing circuit, the signal processing circuit performs a process in accordance with the control signal. When the determination circuit does not determine that the control target is the signal processing circuit, the signal processing circuit outputs the control signal from the second terminal.