Image analysis – Image transformation or preprocessing – Changing the image coordinates
Reexamination Certificate
2001-08-21
2003-01-14
Tran, Phuoc (Department: 2621)
Image analysis
Image transformation or preprocessing
Changing the image coordinates
C382S300000, C358S447000, C358S525000
Reexamination Certificate
active
06507677
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a device and a method for adjusting, by a desired magnification, the number of pixels of image data which is displayed or printed using a data processing device.
DESCRIPTION OF THE PRIOR ART
In personal computers, printers and various other data processing devices, when transferring image data between applications having different image data resolutions, an image data adjusting process is carried out for a resolution adjustment by increasing or decreasing the number of pixels of the image data. Further, when storing image data having a large number of pixels into a memory, a process is performed to decrease the number of pixels of the image data for reducing a storage capacity of the memory. The number of the pixels of the image data may also be reduced upon transmitting the image data via a communication line for reducing a transmission time.
When, for example, increasing the number of pixels of image data by integer times (integral magnifications) in width and height directions (X- and Y-directions), respectively, each pixel is copied as many times as represented by the magnifications in the X- and Y-directions. Accordingly, for example, each pixel is copied N times in the X-direction and M times in the Y-direction so that image data having N×M times pixels can be obtained.
On the other hand, when increasing the number of pixels of image data by a magnification of a real number not an integer, such as 1.5 times or 2.5 times, in either direction, the pixels to be copied and the pixels not to be copied are mixed to achieve such a magnification.
For increasing the number of pixels, it is the simplest to add a pixel of the same pixel value at a subsequent position. However, in case of an image expressing the halftone, unnatural shade is generated to deteriorate the quality of the image when displayed or printed. This is particularly significant when adjusting the number of pixels of image data by a non-integral magnification.
Accordingly, for achieving smooth change in pixel values of pixels in an output image which are increased by copying, a proper calculation is carried out by referring to a plurality of peripheral pixels. This is called a resampling process, wherein the method of first degree interpolation or the like is used for calculating pixel values of the respective pixels.
However, the foregoing conventional technique has the following problem:
For calculating pixel values of output pixels in an output image using the method of first degree interpolation or the like, it is necessary to provide in advance pixel values of input pixels disposed around each of the output pixels whose pixel values are to be derived. Accordingly, it is necessary that, for example, substantially one-page image data or the like be stored in advance in a buffer memory and then read out in turn to be subjected to a given process.
Thus, the conventional technique can not achieve the effective use of the memory and prolongs an image data processing time.
SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide an improved image data adjusting device.
It is another object of the present invention to provide an improved image data adjusting method.
According to one aspect of the present invention, there is provided an image data adjusting device for adjusting the number of pixels of input image data to obtain output image data, the device comprising: a data adjusting table representing magnifications for all the pixels of the input image data per direction in which the number of the pixels of the input image data is adjusted; and a data adjusting section which refers to the data adjusting table to copy each of the pixels serially inputted in a scan direction as many times as represented by the corresponding magnification of the data adjusting table, thereby to obtain the output image data.
According to another aspect of the present invention, there is provided an image data adjusting method for adjusting the number of pixels of input image data to obtain output image data, the method comprising the steps of: preparing a data adjusting table representing magnifications for all the pixels of the input image data per direction in which the number of the pixels of the input image data is adjusted; and referring to the data adjusting table to copy each of the pixels serially inputted in a scan direction as many times as represented by the corresponding magnification of the data adjusting table, thereby to obtain the output image data.
According to another aspect of the present invention, there is provided an image data adjusting device for adjusting the number of pixels of input image data to obtain output image data, the device comprising: a magnification deriving section which derives, based on a predetermined regular relationship between positions of the pixels in the input image data as seen in a pixel adjusting direction of the input image data and magnifications of the corresponding pixels, a magnification for each of the pixels in the pixel adjusting direction of the input image data; and a data adjusting section which copies each of the pixels serially inputted in a scan direction as many times as represented by the magnification derived by the magnification deriving section, thereby to obtain the output image data.
According to another aspect of the present invention, there is provided an image data adjusting method for adjusting the number of pixels of input image data to obtain output image data, the method comprising the steps of: performing a modulo arithmetic relative to a position coordinate of each of the pixels in the input image data as seen in a pixel adjusting direction of the input image data; deriving a magnification for each of the pixels in the pixel adjusting direction of the input image data corresponding to a result of the modulo arithmetic; and copying each of the pixels serially inputted in a scan direction as many times as represented by the derived magnification, thereby to obtain the output image data.
According to another aspect of the present invention, there is provided an image data adjusting method, wherein the number of pixels of input image data is increased by a given magnification in a given direction to obtain output image data and a pixel value of each of pixels of the output image data is subjected to a first degree interpolation based on a position of each of the pixels of the output image data in an image represented by the input image data, the method comprising the steps of: setting a pixel value of each of the pixels of the input image data to be equal to a pixel value of a pixel at a corner of a tetragonal block corresponding to one of the pixels of the input image data and obtained by increasing the number of the pixels of the input image data by the given magnification; and first-degree-interpolating pixel values of the other pixels forming the tetragonal block based on pixel values of pixels at corners of adjacent tetragonal blocks.
According to another aspect of the present invention, there is provided an image data adjusting method for increasing the number of pixels of input image data by a given magnification in a given direction to obtain output image data, the method comprising the steps of: setting a tetragonal lattice formed by the pixels of the input image data at a corresponding position in an image represented by the output image data; and first-degree-interpolating pixel values of output pixels included in the tetragonal lattice based on pixel values of the input pixels forming the tetragonal lattice.
It may be arranged that one of the output pixels in the tetragonal lattice is selected and subjected to a first-degree-interpolation, and each of the pixel values of the other output pixels in the tetragonal lattice is derived by applying to a result of the first-degree-interpolation a conversion process based on a positional relationship to the selected pixel.
According to another aspect of the present invention, there is provided an image data
Ito Kazuhiko
Miura Hideki
Urasawa Koji
Akin Gump Strauss Hauer & Feld L.L.P.
Oki Data Corporation
Sherali Ishrat
Tran Phuoc
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