Image reader, image forming and reproducing apparatus, and image reading method

An image forming and reproducing apparatus comprising:

• an image reader configured to read an image from an original;
• and
• a printing unit configured to reproduce the image read by the image reader on a recording medium, wherein the image reader includes:
• an image sensor configured to receive a light beam reflected from an original to be read and output as an analog pixel signal corresponding to a light quantity of the received light beam;
• a variable-gain amplifier configured to amplify the analog pixel signal to a prescribed level;
• an analog-to-digital converter configured to convert the amplified analog pixel signal to digital image data;
• and
• correction means for performing correction on the A/D converted digital image data according to a prescribed criterion, using a data value corresponding to an original level of the analog pixel signal before the amplification,
• wherein the correction according to the prescribed criterion is a linearity correction with reference to a target linearity characteristic.

An image reading method comprising the steps of:

• receiving a light beam reflected from an original to be read at an image sensor and outputting an analog pixel signal corresponding to a light quantity of the received light beam;
• amplifying the analog pixel signal to a prescribed level using a variable-gain amplifier;
• converting the amplified analog pixel signal to digital image data;
• and
• performing correction on the A/D converted digital image data according to a prescribed criterion, using a data value corresponding to an original level of the analog pixel signal before the amplification,
• wherein the correction performed according to the prescribed criterion is a linearity correction with reference to a target linearity characteristic.

An image reader comprising:

• an image sensor configured to receive a light beam reflected from an original, divide analog pixel outputs generated based on a light-receiving quantity into a first-part analog pixel signal and a last-part analog pixel signal in a scan direction, and output the first-part analog pixel signal and the last-part analog pixel signal in first and second channels, respectively;
• an analog-to-digital converter provided to each of the first-part analog pixel signal and the last-part analog pixel signal and configured to convert the analog pixel signal to digital image data;
• a digital output level detection circuit configured to detect an output level of the digital image data of each of the first and second channels;
• a table creating circuit configured to compare the detected output level of the first channel with the output level of the second channel and create a correction table for correcting for an output level difference between the first and second channels based on the comparison result;
• and
• a pixel rearrangement circuit configured to rearrange the digital image data of the first and second channels having been subjected to correction using the correction table into a time series signal sequence.

An image forming and reproducing apparatus comprising:

• an image reader configured to read an image from an original;
• and
• a printing unit configured to reproduce the image read by the image reader on a recording medium, wherein the image reader comprises:
• an image sensor configured to receive a light beam reflected from an original, divide analog pixel outputs generated based on light-receiving quantity into a first-part analog pixel signal and a last-part analog pixel signal in a scan direction, and output the first-part analog pixel signal and the last-part analog pixel signal in first and second channels, respectively;
• an analog-to-digital converter provided to each of the first-part analog pixel signal and the last-part analog pixel signal and configured to convert the analog pixel signal to digital image data;
• a digital output level detection circuit configured to detect an output level of the digital image data of each of the first and second channels;
• a table creating circuit configured to compare the detected output level of the first channel with the output level of the second channel and create a correction table for correcting for an output level difference between the first and second channels based on the comparison result;
• and
• a pixel rearrangement circuit configured to rearrange the digital image data of the first and second channels having been subjected to correction using the correction table into a time series signal sequence.