Image analysis – Color image processing – Compression of color images
Reexamination Certificate
1997-08-28
2001-03-27
Au, Amelia (Department: 2723)
Image analysis
Color image processing
Compression of color images
C382S167000, C382S250000
Reexamination Certificate
active
06208754
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a device which compresses color still image data, for example, in accordance with a JPEG (Joint Photographic Expert Group) algorithm and records the compressed image data in a recording medium and, also, to a device which reads the compressed image data from the recording medium and expands the compressed image data to reproduce the color still image.
2. Description of the Related Art
A standard algorithm, for the encoding of high resolution images and the transfer of that information through telecommunication transmission channels, has been recommended by the JPEG. In order to enable a large-scale data compression, the baseline process of the JPEG algorithm breaks down the original image data into components on a spatial frequency axis using a two-dimensional DCT process. Thereafter, the data expressed on the spatial frequency axis is quantized by using a quantization table. The quantized data is then encoded using a Huffman table.
There is known a so-called pixel offset method, in which, for example, one color still image is color-separated into red, green and blue images. These three images are then offset with respect to each other, by, for example, one-third of one pixel in a horizontal direction, as they are formed on an imaging device. According to the pixel offset method, a high definition image can be obtained, because the pixel data are now obtained for every one-third of a pixel.
In a conventional device, when compressing the image data, which are obtained by using the pixel offset method, according to the JPEG, as a pre-stage of the image process, a high definition image is initially generated using all of the color pixel data obtained by the pixel offset method, and then, a compression process is carried out on the high definition image. Therefore, the time it takes to record the compressed image data in a recording medium is extended, and the amount of the compressed data is large.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an image compression device in which a recording operation, in which image data obtained by the pixel offset method are compressed and recorded in a recording medium, can be performed in a short time, and the amount of the compressed image data can be reduced.
According to the present invention, there is provided an image compression device comprising a pixel data input processor, a compressed image recording processor and an offset information recording processor.
The pixel data input processor inputs pixel data, which is contained in a plurality of image data, to the image compression device, the plurality of image data being offset to each other. The compressed image recording processor compresses the pixel data, while the plurality of image data remain offset to each other, to obtain compressed image data, and records the compressed image data in a recording medium. The offset information recording processor records offset information, indicating that the plurality of image data are offset to each other, in the recording medium.
Another object of the present invention is to provide an image expansion device which can reproduce the compressed image data obtained by the image compression device.
According to the present invention, there is provided an image expansion device which expands compressed image data recorded in a recording medium, in which offset information is also recorded, the device comprising an image reading processor, an information reading processor, a pixel data reproducing processor and an image generating processor.
The image reading processor reads the compressed image data from the recording medium. The information reading processor reads the offset information from the recording medium. The pixel data reproducing processor expands the compressed image data to reproduce pixel data corresponding to a plurality of image data which are offset to each other. The image generating processor executes a high definition process, based on the offset information, to the pixel data, so that one high definition image corresponding to the plurality of image data is obtained.
Further, according to the present invention, there is provided an image expansion device which expands compressed image data recorded in a recording medium, in which offset information is also recorded, the device comprising an image reading processor, an information reading processor, a signal reproducing processor, an image data reproducing processor and an image generating processor.
The image reading processor reads the compressed image data from the recording medium. The information reading processor reads the offset information from the recording medium. The signal reproducing processor expands the compressed image data to reproduce a luminance signal and color differential signals. The image data reproducing processor reproduces a plurality of image data, which comprise red, green and blue image data and are offset to each other, based on the luminance signal and the color differential signals. The image generating processor executes a high definition process, based on the offset information, to the plurality of image data, so that one high definition image corresponding to the plurality of image data is obtained.
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Asahi Kogaku Kogyo Kabushiki Kaisha
Au Amelia
Greenblum & Bernstein P.L.C.
Johnson Timothy M.
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