Facsimile and static presentation processing – Static presentation processing – Attribute control
Reexamination Certificate
1997-10-29
2001-11-06
Popovici, Dov (Department: 2622)
Facsimile and static presentation processing
Static presentation processing
Attribute control
C358S521000
Reexamination Certificate
active
06313924
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates an image processing method of taking in image data by, for example, reading the image on a document with a scanner, performing a specific process on the input image data, and then outputting the image data on paper with an electronic photographic laser printer and an image processing apparatus, such as a digital copying machine, using the image processing method.
With an image processing apparatus, such as a digital copying machine's body dealing with image data, the image data read from a document by a reading device, such as a scanner, is generally digitized, made multi-valued, and processed according to the purpose, and outputted on an output device, such as a laser printer. In this case, because of the characteristics of the scanner acting as the input device and the photosensitive member and laser optical system in the output device, the desired result cannot be obtained without correction.
In general, to correct the characteristic of the entire system, including the characteristics of the scanner of the input device and the photosensitive member and laser optical system in the output device, a gradation correction table used to correct the characteristic of the entire system beforehand is stored in a memory such as a ROM. The characteristic is corrected by referring to the table. In another approach, each image processing device's body is forced to output a thing from which the gradation characteristic can be known, such as a test print. The test print is then supplied to the input device. From the inputted data, a characteristic correction table for correcting the gradation characteristic is formed. The gradation characteristic is corrected to by reference to the table.
Even if the characteristics of the input device, the output device, and the like are obtained beforehand and stored in such a memory as a ROM and a correction is made by reference to the correction data, it is difficult to make a correction appropriate for each image processing apparatus because the characteristics of the scanner, photosensitive member, and laser optical system differ from one image processing apparatus to another.
To make a correction for each image processing apparatus, the gradation data internally generated in the image processing apparatus is printed at the printer section to provide a hard copy. The hard copy is read by the same image processing apparatus that has generated the gradation data. From the read data, the characteristic correction data for correcting the characteristics of the input device and output device is obtained. This approach is very effective theoretically.
Actually, however, when data on each gradation is obtained by generating gradation data, outputting it on the printer section acting as the output device, and supplying the outputted gradation data to the input device, the relationship between the gradation data sent to the output device and that supplied to the input device plotted on the ordinate and abscissa axes is not ideal. Examples of the data are shown in
FIGS. 9 and 10
.
As shown in the examples, when the data rises sharply or the data contains a part lying as if it were almost parallel with the abscissa, small noise (the portion indicated by “a” in
FIG. 9
or the portion indicated by “b” in
FIG. 10
) may make the characteristic correction data discontinuous or cause the reversal of numerical values in the parts close to the abscissa and ordinate axes.
It is very easy for a person to correct the discontinuity or reversal of the data due to noise, while seeing it with his or her eyes. It is very difficult, however, to do the same thing using calculating expressions. Actually, because of such noises, the characteristic correction data cannot be created exactly.
This causes the problem of being unable to get the linearity as expected theoretically, even if the gradation data is corrected for each digital copying machine.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide an image processing apparatus for and method of creating ideal characteristic correction data and achieving high shading reproducibility without being affected by the discontinuity of the data and the reversal of numerical values caused by noise in creating characteristic correction data used to correct the input and output characteristics of the entire image processing system.
The foregoing object is accomplished by providing 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, the image forming apparatus comprising: means for generating a first gradation pattern with a plurality of density areas; first formation means for 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; means for taking in the second gradation pattern on the first image medium by use of the input function and generating a third gradation pattern; means for 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; combining means for combining the first correction data item and the second correction data item to generate a third correction data item; and second formation means for correcting the image data entered by the input function on the basis of the third correction data item and forming the corrected image data on a second image medium.
With the above configuration, the present invention produces the following effect. To create correction data used to correct the gradation characteristic for each model of copying machine, a gradation pattern P
1
serving as an ideal reference in a digital copying machine is generated (see FIG.
16
). The gradation pattern P
1
is corrected using a first correction data item fl and then printed so that it may be used to correct the deviation in the output system including the printer section to provide an ideal relationship between the input and the output. The printed gradation pattern P
2
is read by the scanner, which produces a third gradation pattern P
3
including the deflection in the input system including the scanner section. Next, a second correction data item f
2
used to make a correction so that the third gradation pattern P
3
may be equivalent to the first gradation pattern P
1
acting as the original reference. Specifically, a combination data is obtained on the basis of the prepared first correction data f
1
and the made second correction data f
2
. The combination of correction data items f
1
and f
2
is determined to be a third correction data item f
3
used to correct the deflection in the entire machine of the model. In an ordinary process, a document image is inputted and corrected using the third correction data item. This removes the deflection in both of the input system including the scanner section and the output section including the printer section, or the deflection in the entire machine. Therefore, it is possible to provide a digital copying machine that makes a correction, taking into account the deflection in the machine itself, and reproduces the gradation density of the image of the document with fidelity.
The foregoing object is also accomplished by providing a method of correcting the gradation characteristic of 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, the method includes the step of generating a first gradation pattern with a plurality of density areas; a first formation step of correcting the first gradation pattern on the basis of a first correction data item previously stored to
Foley & Lardner
Kabushiki Kaisha Toshiba
Popovici Dov
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