Image processing apparatus and method
AssigneeFujitsu Microelectronics Limited
InventorSusumu Kashiwagi
Life of this patent
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Abstract
An image processing apparatus capable of controlling the amount of codes in the image data of one image through one-pass encoding, without changing a quantization table. A Discrete Cosine Transformation (DCT) unit performs discrete cosine transformation on each MCU of the image data of the image. A quantizer quantizes DCT coefficients resulted from the discrete cosine transformation, using the quantization table. A code amount controller sets a threshold value for each MCU based on a target amount of codes for one image and the amount of codes usable for the unprocessed MCUs, reduces the quantized DCT coefficients based on the threshold value, in order to adjust the amount of codes to be generated in the MCU.
Claims12
An image processing apparatus for compression-encoding image data in a JPEG format, comprising:
- a discrete cosine transformation unit for performing discrete cosine transformation on image data of one image for each processing unit area;
- a quantizer for quantizing transformation coefficients resulted from the discrete cosine transformation, using a quantization table;
- and
- a code amount controller for setting a threshold value for the each processing unit area based on a target amount of codes for the one image and an amount of usable codes for unprocessed processing unit areas, and reducing the transformation coefficients quantized, based on the threshold value, in order to adjust an amount of codes to be generated in the each processing unit area.
An image processing method for compression-encoding image data in a JPEG format, comprising:
- performing discrete cosine transformation on image data of one image for each processing unit area;
- quantizing transformation coefficients resulted from the discrete cosine transformation, using a quantization table;
- setting a threshold value for the each processing unit area based on a target amount of codes for the one image and an amount of usable codes for unprocessed processing unit areas;
- and
- reducing the transformation coefficients quantized, based on the threshold value, in order to adjust an amount of codes to be generated in the each processing unit area.
Dependencies are inferred from the claim text.