Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1998-07-27
2001-05-15
Grant, II, Jerome (Department: 2624)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S404000
Reexamination Certificate
active
06233066
ABSTRACT:
TITLE OF THE INVENTION
Image processing apparatus, image processing method and image reading apparatus
BACKGROUND OF THE INVENTION
The present invention relates to an image processing apparatus and an image processing method which store image data obtained by reading an original image by manual operation in an image memory on the basis of reading position data corresponding to the obtained image data. More particularly, the present invention relates to an image processing apparatus, an image processing method and its image reading apparatus each having a function capable of reading gray-scale image data, and its image reading apparatus.
In a conventional image reading apparatus, when an original image larger than the size of the image reading portion of a scanner is read, the apparatus has been configured such that the image is scanned a plurality of times on the original image by manually moving the scanner so that a plurality of divided images can be input. Therefore, in the conventional image reading apparatus, the plural pieces of divided image data are combined to obtain a single piece of image data, and the data is stored. The method disclosed in Japanese Laid-open Patent Application No. (Tokkai Hei) 2-159678, for example, has been known as a method of combining divided image data.
In the conventional combining method disclosed in Japanese Laid-open Patent Application No. 2-159678, a plural pieces of image data having been input dividedly are stored in an image memory. In this combining method disclosed in this Patent Application, by indicating the data in the image memory, displacements at the connection of images are confirmed, and joint end portions are designated to combine the images.
In the combining method of the conventional image reading apparatus, by combining images as described above, a composite image having few dislocation of connection is obtained in fine line pattern of characters, figures and the like.
However, in the scanner of the conventional image reading apparatus for connecting and combining images, in addition to eliminating pattern dislocations in characters, figures and the like, in case of reading by scanning a half-tone image, such as a photo image, it is necessary to prevent the generation of gray-level shifts in the image.
FIG. 33
is a view illustrating a change in gray level in the conventional image reading apparatus. The curve shown in
FIG. 33
indicates a change in an image signal
100
used as an output signal obtained when an image on an original having a constant density is read at a plurality of sampling points. In other words, the curve indicates a change in gray-level data. As shown in
FIG. 33
, in the conventional image reading apparatus, the amount of light reflected from the original is changed by the inclination of the scanner caused during scanning. Consequently, gray-level data is changed even when the image on the original having the constant gray level is read. Since it is very difficult to maintain the inclination of the scanner at a constant angle during a manual operation in particular, gray-level data is therefore changed though in a gradual manner.
FIG. 34
is a view illustrating a method of creating a composite image C by combining images A and B having already been read. The images A and B are input by a line sensor. Even when the images are not read uniformly, gray-level differences occur at the connection portion of the composite image in the same way. When the images A and B having such gray-level differences are combined, reading positions cannot be detected accurately. Therefore, it is difficult to determine positions, on the basis of which composition is carried out.
For these reasons, in the conventional scanner, dislocations and gray-level differences are generated at the connection portion of the composite image, whereby the quality of the image is impaired significantly.
SUMMARY OF THE INVENTION
In order to solve the above-mentioned problems, the present invention is intended to provide an image processing apparatus, an image processing method and an image reading apparatus thereby capable of preventing the generation of density differences at the connection portion of an image even if the change of gray-level arises at a scanning time for reading, and thereby capable of producing a connected composite image having high quality.
In order to attain the above-mentioned object, the image processing apparatus in accordance with the present invention comprises:
an input means for reading image data;
an image memory which is sequentially supplied with reading position data corresponding to the image data having been read and stores the image data on the basis of the reading position data;
a density difference detection means for sequentially detecting the density differences between the image data and storage data stored in the image memory at an overlapping area read by overlap scanning;
a density correction means for correcting the gray-level values of the image data on the basis of the density differences; and
a data storage means for performing control to store the corrected image data in the image memory.
Therefore, the image processing apparatus of the present invention can accurately read density images having improved image quality.
Furthermore, in the image processing apparatus in accordance with the present invention, the density difference detection means detects the differences between the ground density of the image data in the read source image and the ground gray levels of the storage data stored in the image memory as density differences at an overlapping scanning area read by overlap scanning.
Therefore, the image processing apparatus of the present invention can accurately detect density joining at the ground density portion for image connection on a text original wherein high accuracy is required.
Furthermore, in the image processing apparatus in accordance with the present invention, the density difference detection means detects the density differences between the image data and the storage data stored in the image memory as density differences at an overlapping scanning area read by overlap scanning.
Therefore, the image processing apparatus of the present invention can accurately detect density differences at an image connection portion of a photo original wherein high accuracy is required.
Furthermore, in the image processing apparatus in accordance with the present invention, the density correction means is configured so that the average of the detected density differences is used as a correction amount and is added to or subtracted from the image data.
Therefore, in the image processing apparatus of the present invention, the average of the obtained density differences is used as the correction amount and is added to or subtracted from the image data, whereby an effect due to improper detection of density differences can be reduced.
Furthermore, in the image processing apparatus in accordance with the present invention, the density difference detection means is configured to detect density differences in units of reading scanning line.
Therefore, in the image processing apparatus of the present invention, density differences are detected in units of reading scanning line, whereby hardware can be made smaller, and cost can be reduced. Moreover, since the image processing apparatus of the present invention can carry out sequential correction for the input image, the density differences at the connection portion of the image can be sequentially corrected by preventing the generation of uneven gray levels, whereby image composition can be carried out accurately.
Furthermore, the image processing apparatus in accordance with the present invention further comprises a first abnormality detection means which judges whether density differences are abnormal or not by comparing the density differences with a predetermined judgment value.
Therefore, the image processing apparatus of the present invention can prevent image deterioration due to the inclination or the like of the main body of a han
Kataoka Masao
Koga Toshiaki
Kojima Akio
Kuwahara Yasuhiro
Naka Teruyuki
Akin Gump Strauss Hauer & Feld L.L.P.
Grant II Jerome
Matsushita Electric - Industrial Co., Ltd.
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