First relational equations which represent characteristics of respective sample colors are obtained, and for the respective sample colors, prediction values of spectral characteristics of characteristics-acquired gradation values for a prediction target color are obtained using the first relational equations. Difference values between the prediction values and actual measurement values are obtained, and a sample color for which a minimum difference value is obtained is selected as a reference color. A second relational equation that represents characteristics of the reference color is obtained, and a prediction value of spectral characteristics of a prediction target gradation value for the prediction target color is obtained using the second relational equation.

An apparatus comprises a unit configured to generate gradation data corresponding to an achromatic color generated by combining two or more colors among a plurality of colors, for an excess amount of a total gradation value exceeding a predetermined value, the total gradation value being a sum of gradation values of the plurality of colors used for recording a pixel of interest, and generate gradation data corresponding to the plurality of colors, based on the generated gradation data corresponding to the achromatic color; and a unit configured to quantize the generated gradation data, and generate data to control recording of dots corresponding to the pixel of interest. The predetermined value is a gradation value indicating whether or not to record the dots in an overlapping manner, in case that the dots corresponding to the total gradation value are recorded.

An apparatus for image conversion includes a processor configured to classify a reference region representing a predetermined feature into a shadowed region and an unshadowed region, the reference region being in an aerial image represented in RGB color space; determine a tone correction factor so that a difference between an average luminance of the shadowed region and an average luminance of the unshadowed region in the aerial image represented in predetermined color space to which the color space of the aerial image is converted from RGB color space is less than a difference between an average luminance of the shadowed region and an average luminance of the unshadowed region represented in RGB color space; correct tones of the aerial image with the tone correction factor; and convert the color space of the aerial image from RGB color space to the predetermined color space to generate a color conversion image.

In a document represented by CMYK process colors, a color that a user wishes to remove is prevented from remaining without being removed by specified color removal, and even a color that the user does not wish to remove by rights is prevented from being removed.

Provided is an image processing method for generating print data, the method including an ink amount generating step for generating CMYK data based on image data. The ink amount generating step determines the CMYK data based on a brightness L* calculated using a function f3(D) satisfying f1(D)≥f3(D) in a range of the gradation values D from a coordinates Pk to a coordinates Ps and also satisfying f1(D)≥f3(D) in at least part of the range.

An image reading apparatus includes: a reader that reads an image on a print medium, and is arranged at a reading position of a conveyance path for conveying the print medium that is continuous and has a long length; a shading unit including a reference color member to perform shading correction of correcting a read value of an image sensor in the reader; a mover that moves the shading unit between the reading position of the reader and a retreated position; and a retractor that retracts the print medium from the reading position of the reader, wherein the retractor arranges the print medium at the reading position of the reader at a time of reading by the reader, and retracts the print medium from the reading position of the reader at an end of reading by the reader, to secure a predetermined space between the reader and the print medium.

An image processor performs a histogram acquisition step of acquiring a histogram representing a distribution of gradation values of pixels in a fundus color image captured by irradiating a fundus with a plurality of beams of single-color light having different wavelengths, the histogram being acquired for each channel corresponding to each beam of single-color light, a histogram correction step of acquiring a corrected histogram by correcting the histogram of each channel acquired in the histogram acquisition step, of which a target pattern is set for each channel in advance, so as to fit to the corresponding target pattern, and a color tone corrected image generation step of generating a color tone corrected image, in which a distribution of gradation values for each channel is represented by the corrected histogram, based on the corrected histogram of each channel.

An apparatus includes one or more processors that function as an image acquisition unit configured to acquire a training image and a correct answer image, a generation unit configured to input the training image to a neural network to generate an output image, an error acquisition unit configured to subject each of the correct answer image and the output image to processing for adjusting a color signal value, and acquire an error between the correct answer image and the output image that have been subjected to the processing, and an update unit configured to update parameters of the neural network based on the acquired error.

An image forming apparatus includes a forming unit, a generation unit, a storage unit, a correction unit, and a changing unit. The forming unit forms an image. The generation unit generates correction data for correcting density unevenness for each of a plurality of regions divided in a main scanning direction of an image formed by the forming unit. The storage unit stores the correction data generated by the generation unit. The correction unit corrects a density of an image to be formed by the forming unit for each of the plurality of regions based on the correction data stored by the storage unit. The changing unit changes an image formation density by the forming unit with a uniform amount of change for the plurality of regions after the correction data is generated by the generation unit.

According to the invention, the saturation thresholds (th.sub.r; th.sub.g; th.sub.b) used for this detection depend on color coordinates (r.sub.w, g.sub.w, b.sub.w) representing an illuminant (ILL) of the image.