Abstract: An image forming apparatus which includes the input function of taking in image data on a document by scanning and the output function of forming an image on the basis of the image data, includes the generating function of generating a first gradation pattern with a plurality of density areas, a first formation function of correcting the first gradation pattern on the basis of a first correction data item previously stored to produce a second gradation pattern and forming the second gradation pattern on a first image medium by use of the output function, the taking-in function of taking in the second gradation pattern on the first image medium by use of the input function and outputting a third gradation pattern, the function of creating a second correction data item used to make a correction so that the density in each of a plurality of density areas of the third gradation pattern may be essentially equal to the density in each of a plurality of density areas of the first gradation pattern, the combining fun

Abstract: In order to reduce the storage capacity of a memory for a density adjusting table and change the density adjustment range with a relatively high degree of freedom, a density characteristic adjusting table section corresponding to set density based on reference data of light, center and dark for density characteristic adjustment previously stored in a correction data table section is created in a table forming section, a density characteristic adjustment value corresponding to an input image signal from a scanner section is derived by effecting the linear interpolation according to neighboring density characteristic adjustment values based on the input image signal in a density characteristic adjustment value calculating section, and the input image signal is corrected by use of the derived density characteristic adjustment value in a density characteristic adjusting section and then output to a printer section as an output image signal.

Abstract: In order to reduce the storage capacity of a memory for a density adjusting table and change the density adjustment range with a relatively high degree of freedom, a density characteristic adjusting table section corresponding to set density based on reference data of light, center and dark for density characteristic adjustment previously stored in a correction data table section is created in a table forming section, a density characteristic adjustment value corresponding to an input image signal from a scanner section is derived by effecting the linear interpolation according to neighboring density characteristic adjustment values based on the input image signal in a density characteristic adjustment value calculating section, and the input image signal is corrected by use of the derived density characteristic adjustment value in a density characteristic adjusting section and then output to a printer section as an output image signal.

Abstract: An image processing apparatus comprises a scanner mechanism for fetching an image, a function of preparing a density histogram on the basis of the fetched image, a decision function of deciding a sort of the fetched image corresponding to a histogram distribution of a background area when the density histogram is divided into the background area and a character area having an image density higher than the background area, and a first image density frequency having a maximum frequency within a range of the background area, and a circuit for correcting a gradation of the fetched image, in accordance with a decision result of the decision function.

Abstract: An image forming apparatus, which converts the analog image read in lines into a digital image containing the density information in pixels, comprises a histogram creating circuit that converts the density information on the target pixels in the digital image into multiple values and creates a histogram having the frequency for each density, a peak density value determining circuit that determines the peak density values of two points at which the frequency of the density histogram peaks, a computing circuit that computes a reference value for density correction of the digital image on the basis of the frequency of the peak density value, a circuit that judges the type of the image on the basis of the features of the density histogram, a circuit that corrects the reference value on the basis of the judged type of the image, and a circuit that corrects the density information about the digital image on the basis of the corrected reference value.

Abstract: An image forming apparatus, which converts the analog image read in lines into a digital image containing the density information in pixels, comprises a histogram creating circuit that converts the density information on the target pixels in the digital image into multiple values and creates a histogram having the frequency for each density, a peak density value determining circuit that determines the peak density values of two points at which the frequency of the density histogram peaks, a computing circuit that computes a reference value for density correction of the digital image on the basis of the frequency of the peak density value, a circuit that judges the type of the image on the basis of the features of the density histogram, a circuit that corrects the reference value on the basis of the judged type of the image, and a circuit that corrects the density information about the digital image on the basis of the corrected reference value.