Computer graphics processing and selective visual display system – Computer graphics processing – Three-dimension
Reexamination Certificate
1995-10-16
2001-05-15
Jankus, Almis R. (Department: 2671)
Computer graphics processing and selective visual display system
Computer graphics processing
Three-dimension
Reexamination Certificate
active
06232978
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to magnification or “zoom” processing, particularly reduction processing, of a digital binary image, and to an image processing apparatus and method for obtaining a high-quality zoomed image using contour information.
2. Description of the Related Art
The applicant has already filed applications for such an apparatus disclosed publicly as Japanese Patent Application Laid-Open (KOKAI) No. 5-174140 (prior art {circle around (1)}) and Japanese Patent Application Laid-Open (KOKAI) No. 6-12490 (prior art {circle around (2)}).
According to each of these applications, a binary image per se is not varied in power, or zoomed, when it is desired to output the binary image upon changing its magnification. Rather, contour information of the binary image is extracted and a zoomed image is produced based upon the contour information extracted, whereby it is possible to obtain a high-quality image.
More specifically, Japanese Patent Application Laid-Open No. 5-174140 (prior art {circle around (1)}) teaches to extract an outline vector from a binary image, create a smoothly zoomed outline vector at a desired rate of magnification (arbitrary) in the state of the extracted outline vector representation, and reproduce a binary image from the smoothly zoomed outline vector. In this manner it is attempted to obtain a high-quality digital binary image varied in power at the desired rate of magnification (arbitrary).
The principal elements of this arrangement will be described in general terms.
FIG. 9
is a diagram which best illustrates the features of Japanese Patent Application Laid-Open No. 5-174140.
As shown in
FIG. 9
, a binary image acquisition unit
1
acquires a digital binary image that is to undergo zoom processing and outputs the binary image in a raster-scan format. An outline extraction unit
2
extracts a coarse contour vector (an outline vector prior to smoothing and zoom processing) from the binary image having the raster-scan format. An outline smoothing/zooming unit
3
smoothes and applies zoom processing to the coarse contour vector data in the form of vector data. A binary image reproduction unit
4
reproduces the binary image data in the raster-scan format from the outline vector data. A binary image output unit
5
displays the binary image data in the raster-scan format, produces a hard copy of the data or outputs the data to a communication line or the like.
The binary image acquisition unit
1
is a well-known raster-scanning type binary image output unit which reads the image of an original as a binary image and outputs the image in a raster-scan format. The outline extraction unit
2
is the apparatus described in the specification of Japanese Patent Application Laid-Open (KOKAI) No. 4-157578 already proposed by the applicant.
FIG. 10
illustrates the scanning of the raster-scan binary image data outputted by the binary image acquisition unit
1
as well as the scanning of the raster-scan binary image data which enters the outline extraction unit
2
. The raster-scan binary image data outputted by the binary image acquisition unit
1
enters the outline extraction unit
2
. In
FIG. 10
, numeral
101
denotes a pixel in the binary image undergoing raster scanning, and numeral
102
represents a nine-pixel area, namely the pixel
101
and the eight pixels neighboring it. The apparatus constituting the outline extraction unit described in the specification of Japanese Patent Application Laid-Open No. 4-157578 mentioned above shifts a pixel of interest in the order in which raster scanning is performed and, with regard to each pixel of interest, detects contour edge vectors (horizontal or vertical vectors) between the pixel of interest and the pixels neighboring the pixel of interest. If a contour edge vector exists, the apparatus extracts the coordinates of the starting point of this edge vector as well as the data indicating the direction of the vector and extracts the coarse contour vector while updating the connection relationship between edge vectors.
FIG. 11
illustrates an example of extraction of contour edge vectors between a pixel of interest and the pixels neighboring it. In
FIG. 11
, the “&Dgr;” mark indicates the starting point of a vertical vector and the “&ogr;” mark the starting point of a horizontal vector.
FIG. 12
depicts an example of coarse-contour vector loops extracted by the outline extraction means described above. Here each box delimited by the grid indicates a pixel position in an input image; blank boxes signify white pixels and the shaded circle marks signify black pixels. As in
FIG. 11
, the “&Dgr;” mark indicates the starting point of a vertical vector and the “&ogr;” mark the starting point of a horizontal vector.
It will be appreciated from the example of
FIG. 12
that the outline extraction unit
2
extracts areas of contiguous black pixels as coarse-contour vector loops in which a horizontal vector and a vertical vector are always interconnected in alternating fashion. It is so arranged that the direction in which extraction processing advances is such that the side to the right of the direction of advance is the area of the black pixels. Further, the starting point of a coarse-contour vector is extracted as a position intermediate each pixel of the input image. In other words, if the present position of each pixel is represented by integers (x,y), then the starting point of an extracted vector is a value obtained by adding 0.5 to or subtracting 0.5 from each of these coordinates. More specifically, a line segment having a width of one pixel in an original image also is extracted as a coarse contour loop having a significant width. A group of coarse-contour vector loops thus extracted is outputted by the outline extraction unit
2
of
FIG. 9
in a data format of the kind shown in FIG.
13
. That is, the data comprises the total number N of contours extracted from the image and a group of coarse-contour loop data from a first contour loop to an N-th contour loop. Each item of coarse-contour loop data is composed of the total number of starting points of contour edge vectors present in a coarse-contour loop (this number can be thought of as the total number of contour edge vectors), and a column of values of starting-point coordinates (x- and y-coordinate values) of each contour edge vector in the order in which the edge vectors construct the loop (the starting point of a horizontal vector and the starting point of a vertical vector are arranged in alternating fashion).
Next, the outline smoothing/zoom unit
3
shown in
FIG. 9
accepts the coarse-contour vector data (see
FIG. 13
) from the outline extraction unit
2
as an input and executes smoothing and zoom processing, which is for zooming to a desired magnification, in the form of the outline vector data (coordinate values).
FIG. 14
illustrates the construction of the outline smoothing/zoom unit
3
in greater detail. As shown in
FIG. 14
, the outline smoothing/zoom unit
3
includes a magnification setting device
310
for zooming, and a first smoothing/zooming device
320
. The first smoothing/zooming device
320
subjects the entered coarse contour data to smoothing and zoom processing at the magnification set by the magnification setting device
310
. The results of processing are smoothed in a second smoothing device
330
, whereby a final output is obtained.
The magnification setting device
310
, which provides information indicating what the magnification of an input image size should be independently in the main-scan (horizontal) direction and sub-scan (vertical) direction, may deliver values, which have been set in advance by a DIP switch or dial switch, to the first smoothing/zoom device
320
, or may have a configuration which supplies the values from some external unit via an interface.
The first smoothing/zoom device
320
obtains the magnification information from the magnification setting device
310
and applies smoothing and zoom processing.
FIG. 15
illustrates an example of hardw
Ishida Yoshihiro
Kawazome Takeshi
Koga Shinichiro
Shigeeda Nobuyuki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Jankus Almis R.
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