Television – Image signal processing circuitry specific to television – Special effects
Reexamination Certificate
2000-09-11
2002-05-21
Lee, Michael (Department: 2614)
Television
Image signal processing circuitry specific to television
Special effects
C348S441000, C345S670000, C382S300000
Reexamination Certificate
active
06392711
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an image processing having image scaling capability.
2. Description of the Related Art
Image processing systems may be required to effect image reduction processing and enlargement processing for scaling images to desired sizes. FIGS.
16
(A)-
16
(D) are diagrams for explaining the nature of conventional vertical image reduction processing. In the original image shown in FIG.
16
(A), image lines numbered
1
,
4
and
7
are filled in black and the other lines are white. The reduced image shown in FIG.
16
(B) is 0.8 time smaller than the original image.
In the reduced image shown in FIG.
16
(B), the lines numbered
1
and
6
of the original image have been dropped and the reduced image is therefore missing one black horizontal line. As can be seen from this example, conventional vertical image reduction processing simply drops a number of lines. Fine line details are therefore sometimes lost. In the reduction of an original image having lines L
1
-L
3
each having a width of one line as shown in FIG.
16
(C), for example, the original line L
3
may be dropped and completely lost after the image reduction as shown in FIG.
16
(D). This problem of line dropping also arises during horizontal reduction.
FIGS.
17
(A) and
17
(B) are diagrams for explaining the nature of conventional vertical image enlargement processing. The original image shown in FIG.
17
(A) is the same as that shown in FIG.
16
(A) referred to above. The enlarged image shown in FIG.
17
(B) is 1.25 times large than the original image. The image of FIG.
17
(B) additionally includes the lines numbered
0
and
4
of the original image. The width of these lines is therefore doubled. As can be seen from this example, conventional vertical image enlargement processing simply adds a number of lines. The thickness of the lines in the image therefore becomes excessively thick. This problem of line addition also arises during horizontal enlargement.
Moreover, the conventional enlargement processing can easily enlarge an image an integer number of times but has difficulty enlarging an image by an arbitrary scale factor including a fractional component.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to mitigate image line dropping during reduction and image line thickening during enlargement. Another object of the present invention is to enable an image to be enlarged by an arbitrary scale factor which may include a fractional component.
In order to attain a least part of the above and other objects of the present invention, there is provided an image processing apparatus comprising a frame memory for storing image data, a vertical reduction unit, and a horizontal reduction unit. The vertical reduction unit reduces an image represented by the image data in the vertical direction when the image data are written to the frame memory, detects a first line which is to be dropped by the reduction, and interpolates a plurality of lines of the image data including the first line and a second line adjacent to the first line to modify an image portion of the second line. The horizontal reduction unit reduces the image represented by the image data in the horizontal direction, detects a first pixel which is to be dropped by the reduction, and interpolates a plurality of pixels of the image data including the first pixel and a second pixel adjacent to the first pixel to modify an image portion of the second pixel.
The vertical reduction unit can detect a first line which is to be dropped by the reduction and prevent total loss of line information at the time of reduction. Since lines not adjacent to those lines which are to be dropped by reduction are not processed by interpolation, image quality degradation owing to the line dropping can be mitigated without appreciably degrading the sharpness of the image. Similarly in horizontal reduction, simple dropping of a pixel during reduction can be prevented and image quality degradation owing to pixel dropping can be mitigated without appreciably degrading the sharpness of the image.
In a preferred embodiment, each of the vertical reduction unit and the horizontal reduction unit comprises: a buffer memory for storing a prescribed amount of input image data; a weighted-averaging unit for obtaining a weighted-average of first image data read from the buffer memory and second image data representing an image portion immediately following the first image data to produce third image data; a selector for selecting and outputting one set from among a plurality of sets of image data including the input second image data and the third image data output by the weighted-averaging unit; and a selection signal generator for generating from an image reduction factor a selection signal indicating an image portion which is to be dropped by the reduction and supplying the selection signal to the selector.
In these reduction units, since one set from among plural sets of image data including the input second image data and the third image data generated by the weighted-averaging unit is selected and output, image data with mitigated dropout during reduction can be generated in real time.
The apparatus may further comprise a write address controller responsive to the selection signal for controlling incrementing of a write address input to the frame memory. By this, image data with mitigated dropout during reduction can be written to an apparatus address in the frame memory.
Preferably, the vertical reduction unit and the horizontal reduction unit each has a reduction factor in the range of 0.5 to 1, whereby the image portion which is to be dropped by the reduction in the vertical reduction unit is one line per location and the image portion which is to be dropped by the reduction in the horizontal reduction unit is one pixel per location.
According to another aspect of the present invention, an image processing apparatus comprises: a frame memory for storing image data; a vertical enlargement unit for enlarging an image represented by the image data read from the frame memory in the vertical direction, detecting the first line which is to be added by the enlargement, and interpolating a plurality of lines of the image data adjacent to the first line to generate image data for the first line, and a horizontal enlargement unit for enlarging an image represented by the image data in the horizontal direction, detecting a first pixel which is to be added by the enlargement, and interpolating a plurality of pixels of the image data adjacent to the first pixel to generate image data for the first pixel.
The vertical enlargement unit can, at the time a first line is added by the enlargement, generate the first line by interpolation of image data of plural lines including the first line and a second line adjacent to the first line. Thickening of a line due to simple addition of the same line during enlargement can therefore be prevented. Since the interpolation is not executed with respect to those lines which are present in the original image, image quality degradation owing to line thickening can be mitigated without appreciably degrading the sharpness of the image. Similarly in horizontal enlargement, simple pixel thickening during enlargement can be prevented and image quality degradation owing to simple pixel addition can be mitigated without appreciably degrading the sharpness of the image.
In a preferred embodiment, each of the vertical enlargement unit and the horizontal enlargement unit comprises: a buffer memory for storing a prescribed amount of input image data; a weighted-averaging unit for obtaining a weighted-average of first image data read from the buffer memory and second image data representing an image portion immediately following the first image data to produce third image data; a selector for selecting and outputting one set from among a plurality of sets of image data including the input second image data and the third image data output by the weighted-averaging unit; and a sel
Lee Michael
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Seiko Epson Corporation
LandOfFree
Image reduction and enlargement processing does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image reduction and enlargement processing, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image reduction and enlargement processing will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2816521