An image forming apparatus outputs a tone chart for calibration by a printer, reads the output tone chart by a scanner, determines whether data on a sheet is affected by a surface shape of the sheet based on the read tone chart, corrects data on a white area of the read chart based on a result of the determination, and executes calibration using the corrected data.

The present disclosure relates to methods and devices for video or frame processing including an apparatus, e.g., a video or frame processor. In some aspects, the apparatus may receive a video stream including a plurality of frames, each of the plurality of frames including luminance information. The apparatus may also perform a histogram analysis on the luminance information for each of the plurality of frames. Additionally, the apparatus may determine whether a difference between the luminance information for each of the plurality of frames and a current luminance distribution is greater than a perceptual threshold. The apparatus may also calculate an updated tone mapping configuration based on the luminance information for a frame when the difference between the luminance information for the frame and the current luminance distribution is greater than the perceptual threshold.

A system accesses an image with each pixel of the image having luminance values each representative of a color component of the pixel. The system generates a first histogram for aggregate luminance values of the image, and accesses a target histogram for the image representative of a desired global image contrast. The system computes a transfer function based on the first histogram and the target histogram such that when the transfer function is applied, a histogram of the modified aggregate luminance values is within a threshold similarity of the target histogram. The system modifies the image by applying the transfer function to the luminance values of the image to produce a tone mapped image, and outputs the modified image.

A system accesses an image with each pixel of the image having luminance values each representative of a color component of the pixel. The system generates a first histogram for aggregate luminance values of the image, and accesses a target histogram for the image representative of a desired global image contrast. The system computes a transfer function based on the first histogram and the target histogram such that when the transfer function is applied, a histogram of the modified aggregate luminance values is within a threshold similarity of the target histogram. The system modifies the image by applying the transfer function to the luminance values of the image to produce a tone mapped image, and outputs the modified image.

A mechanism capable of improving the compression efficiency of image data generated by performing the dark reading is provided. An image processing apparatus comprising a reading unit configured to read a document and generate image data, a reading mode setting unit configured to set a reading mode of the reading unit to a first reading mode or a second reading mode, in which the document is read with the amount of light less than that in the first scanning mode, a background color determining unit configured to determine a background color in the image data generated by the reading unit, and a conversion image generating unit configured to generate image data, in which a color close to the background color in the image data is converted into the background color, in a case that the second reading mode is set.

The present disclosure relates to methods and devices for video or frame processing including an apparatus, e.g., a video or frame processor. In some aspects, the apparatus may receive a video stream including a plurality of frames, each of the plurality of frames including luminance information. The apparatus may also perform a histogram analysis on the luminance information for each of the plurality of frames. Additionally, the apparatus may determine whether a difference between the luminance information for each of the plurality of frames and a current luminance distribution is greater than a perceptual threshold. The apparatus may also calculate an updated tone mapping configuration based on the luminance information for a frame when the difference between the luminance information for the frame and the current luminance distribution is greater than the perceptual threshold.

A mechanism capable of improving the compression efficiency of image data generated by performing the dark reading is provided. An image processing apparatus comprising a reading unit configured to read a document and generate image data, a reading mode setting unit configured to set a reading mode of the reading unit to a first reading mode or a second reading mode, in which the document is read with the amount of light less than that in the first scanning mode, a background color determining unit configured to determine a background color in the image data generated by the reading unit, and a conversion image generating unit configured to generate image data, in which a color close to the background color in the image data is converted into the background color, in a case that the second reading mode is set.

An image processing apparatus of an embodiment includes an image processing unit to convert a color image to a monochrome image. The color image comprises pixels with a plurality of color components. The image processing unit is configured to generate a histogram from the monochrome image showing a color intensity gradation in the monochrome image by pixel frequency. A processor is configured to obtain a first threshold value based on the histogram, determine for each color component of each pixel in the color image whether or not each color component of the pixel is light based on the first threshold value, and generate a corrected color image by removing a background coloring from the color image by correcting each pixel for which all the color components are determined to be light.

In an image data conversion device, color image data is represented in gray scale, a histogram of brightness values is created for the gray-scaled image data, it is determined based on the created histogram which image pattern of a plurality of image patterns the gray-scaled image data is classified into, a range subjected to gamma correction and a range fixed to at least one of a minimum value and a maximum value of gray scale are set for each image pattern, and image data conversion including the gamma correction is performed on the gray-scaled image data.

Embodiments related to local tone mapping for symbol reading. A local pixel neighborhood metric is determined for at least one raw pixel in a region-of-interest, which identifies on one or more raw pixels near the at least one raw pixel. A local mapping function is determined for the at least one raw pixel that maps the value of the raw pixel to a mapped pixel value with a mapped bit depth that is smaller than the bit depth associated with the raw image. The local mapping function is based on a value of at least one other raw pixel near the at least one raw pixel within the local pixel neighborhood metric, and at least one parameter determined based on the raw image. A mapped image is computed for the region-of-interest by applying the local mapping function to the raw image.