| 摘要 |
PURPOSE: A device for processing raster-block conversion data is provided to make as one chip with raster-block conversion, image compression and USB, and to use low-cost external memory(DRAM or SDRAM) as a buffer for storing compressed images and raster images. Raster-block conversion and memory are driven by input clock frequency. An image signal processing part is driven by four divided clock frequency. An image compressing part is driven by two divided clock frequency. Therefore, real-time processing is possible with only one memory regardless of size of image. Size of a chip is reduced. CONSTITUTION: Four-divided clock frequency(12MHz) is inputted into an image signal processor(210). The image signal processor(210) interpolates image signal of 12MHz 8 bit layer format inputted from a CMOS image sensor(202) to 24 bit RGB. Therefore, the image signal is transformed to luminance/color difference data fitting JPEG input. A raster-block converting part(204) receives the luminance/color difference data output from the image signal processor(210), stores the luminance/color difference data in an external memory(246), and reads the raster image stored in the external memory(246) as image of block unit for compression. An image compressing part(270) compresses the block image data output from the raster-block converting part(204) to JPEG(joint photographic coding experts group) or MPEG. The image compressing part(270) operates in two divided clock(24MHz) of an input frequency. A memory(246) executes reading/writing raster image and compressed image in corresponding area. The raster image and compressed image were inputted through the raster-block converting part(204) which stores image compressed by the image compressing part(270) in an external memory(246) again.
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