Facsimile and static presentation processing – Facsimile – Picture signal generator
Reexamination Certificate
1999-08-24
2003-06-24
Lee, Cheukfan (Department: 2722)
Facsimile and static presentation processing
Facsimile
Picture signal generator
C358S444000
Reexamination Certificate
active
06583895
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relate to an image reading method and apparatus for regenerating image data read by an image reading apparatus such as a hand-scanner on an image storage means. More specially, this invention relates to an image data reading apparatus and method able to perform a scanning freely, and to regenerate an image data with high quality in a high speed.
2. Description of the Prior Art
An image scanning apparatus used for reading image data in a flatbed type is generally arranged that an image reading sensor set a plurality of reading elements in a line moves in a specific speed in a vertical direction against the elements arraying direction of the image reading sensor. Under the arrangement, each element scans with a pulse of specific period in a line reading direction (a main scanning) and also scans in a moving direction (a sub scanning), as a result an image data can be acquired from each element. Furthermore, the image data thus obtained is synchronized with the acquisition timing and written into an image data storage means (hereinafter the processing is represented as “map”).
In the above constitution acquisition positions of the image data may be arrayed equally on two axes which make a right angle, that is, in the main scanning direction and the sub scanning direction. Moreover in this case, since each synchronous signal of the main scanning direction and the sub scanning direction synchronizes with the position signals sent to the image storage means, each acquisition position of the image data can be corresponded at one-to-one to each pixel mapping position in the image storage means. Therefore, it can be easy to acquire the image data with high quality.
Besides the image scanning apparatus of the above flatbed type, the applicant of the present invention developed an image reading apparatus of a free scanning type (hereinafter represented as a free scanning apparatus) which is disclosed in the Japanese laid-open publication No. H08-241393. It is possible for the free scanning apparatus to acquire an image data by operating the image reading sensor over an original by hand.
FIG. 28
shows the first step of the reading procedure for an original using the free scanning apparatus. The free scanning apparatus is provided with a wheel
52
and
53
outside each end of the image reading sensor
51
. The free scanning apparatus can read the image data not only in a straight line direction shown as the scanning
341
, but also in a curvilinear direction that the wheels rotate in reverse, which is shown as the scanning
342
.
Namely, it is possible to read the ABCD area by the scanning
341
, and the BEFC area by the scanning
342
. The BEGC area, which is read out above the other at this time, is represented as an overlapped area hereinafter.
And the direction of a straight line AD, which the reading elements are arrayed on and connects the ends of the image reading sensor
51
, is defined as a main scanning direction, while the wheel advancing direction is as a sub scanning direction. Accordingly, the sub scanning direction of the free scanning apparatus does not become a fixed linear direction as shown in the image scanning apparatus of flatbed type.
Therefore, in order to clear the coordinates, a position at which the image reading sensor
51
starts to reading is defined as a reference position, the reading elements arraying direction of the image reading sensor
51
at the reference position is defined as a Y axis, and an axis which is vertical to the Y axis is defined as a X axis. By operating the free scanning apparatus freely, it is possible to read an image data of an arbitrary position for the width of the image reading sensor. A right direction from the reference position is defined as a X positive direction, a downward direction from the reference position is defined as a Y positive direction, and thereby the explanation will be given as follows.
FIG. 29
shows the second step of the reading procedure for an original, and the EHJF area is read out by performing the scanning
345
after the scanning of the first step shown in FIG.
28
.
When the free scanning apparatus as described above reads an image data by a return-back scanning the mapping errors are generated and exert an influence upon the picture quality of the image data Referring to
FIGS. 30 and 31
, the mapping errors will be explained hereinafter.
FIG. 30
shows an illustrated diagram indicating an example of the mapping errors. The white dot
351
represents a pixel position on the image data storage means to be mapped (that is called a mapped pixel position hereinafter), a black dot
352
represents a pixel position corresponding to each element on the image reading sensor
51
, and an arrow
357
represents a sub scanning direction Here, if the read-out pixel position is coincident with the mapped pixel position, the mapping errors (the difference between the white dot position and the black dot position) will not occur.
However, it almost occurs in case of the free scanning that the read-out pixel position is not identical with the mapped pixel position, which is shown as the read-out positions
355
and
356
. But if the scanning position is almost horizontal or almost vertical to the array of the mapped position as shown in
FIG. 30
, there is not so much deterioration of the picture quality because it occurs the mapping errors with very few difference between the read-out pixel position and the mapped pixel position at each element of the image reading sensor
51
.
FIG. 31
is an explanatory diagram showing the other example of generating the mapping errors. In case of a scanning with a slant shown as an arrow
363
, the difference between the read-out pixel position and the mapped pixel position becomes large at each element of the image reading sensor
51
and the mapping errors is generated sharply. Consequently the picture quality deteriorates radically.
Therefore, the image data of the ABCD area mapped at the time of the scanning
341
in
FIG. 28
had better not to be overwritten by the image data of the BEFC area generated by the scanning
342
(a scanning in the X negative direction) after the turn-back
There is a method which does not perform the mapping by the scanning
342
in the X negative direction, but in case that the scanning finishes at the scanning
342
in the X negative direction it occurs that the read-out image data are not be mapped. And as it exerts an influence upon the image synthesis, that method is not preferable.
In the conventional apparatus, the information that the mapping has already finished or not (called a scanning information hereinafter) is stored using a scanning flag as shown in
FIG. 32
or one of gradations as shown in
FIG. 33
(of which the initial status is represented by the gradation
255
, accordingly in case of performing the mapping the gradation is one except
255
). If the scanning flag stands or the gradation excluding a specific one is represented, the mapping has already finished. Accordingly, in case of the scanning
342
in the X negative direction, it can be arranged that the mapping in the overlapped area is not performed.
On the contrary, in case of the scanning
345
in X positive direction again as shown in
FIG. 29
, it is preferable to rewrite the GFC area shown in
FIG. 28
because the picture quality gets better.
However, if the mapping in the X negative direction is restricted by determining to perform the mapping according to whether the scanning flag stands or the gradation is a specific one, the picture quality is improved. But it takes much time to read out the scanning information from the image data storage means (for instance, an image data memory), therefore there is a problem that the time for the mapping processing increases.
In general, since the mapping positions are not arranged consecutively on the image data memory, the access to the memory is a randam access. And in case of using SDRAM (Synchronous DRAM), the time for the reading of the scanning info
Kojima Akio
Kuwahara Yasuhiro
Watanabe Tatsumi
Lee Cheukfan
Matsushita Electric - Industrial Co., Ltd.
McDermott & Will & Emery
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