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JPEG API: Class JPEGCodec - JDK 5 Documentation v1.2.2, Java 2 SDK 英文文档

com.sun.image.codec.jpeg

com.sun.image.codec.jpeg
Class JPEGCodec

java.lang.Object
  |
  +--com.sun.image.codec.jpeg.JPEGCodec
public class JPEGCodec
extends Object

This class is a factory for implementations of the JPEG Image Decoder/Encoder.

Note that the classes in the com.sun.image.codec.jpeg package are not part of the core Java APIs. They are a part of Sun's JDK and JRE distributions. Although other licensees may choose to distribute these classes, developers cannot depend on their availability in non-Sun implementations. We expect that equivalent functionality will eventually be available in a core API or standard extension.

See Also:
JPEGImageDecoder, JPEGImageEncoder

Method Summary
static JPEGImageDecoder createJPEGDecoder(InputStream src)
          This creates an instance of a JPEGImageDecoder that can be used to decode JPEG Data streams.
static JPEGImageDecoder createJPEGDecoder(InputStream src, JPEGDecodeParam jdp)
          This creates an instance of a JPEGImageDecoder that can be used to decode JPEG Data streams.
static JPEGImageEncoder createJPEGEncoder(OutputStream dest)
          This creates an instance of a JPEGImageEncoder that can be used to encode image data as JPEG Data streams.
static JPEGImageEncoder createJPEGEncoder(OutputStream dest, JPEGEncodeParam jep)
          This creates an instance of a JPEGImageEncoder that can be used to encode image data as JPEG Data streams.
static JPEGEncodeParam getDefaultJPEGEncodeParam(BufferedImage bi)
          This is a factory method for creating JPEGEncodeParam objects.
 JPEGEncodeParam getDefaultJPEGEncodeParam(int numBands, int colorID)
          This is a factory method for creating JPEGEncodeParam objects.
static JPEGEncodeParam getDefaultJPEGEncodeParam(JPEGDecodeParam jdp)
          This is a factory method for creating a JPEGEncodeParam from a JPEGDecodeParam.
static JPEGEncodeParam getDefaultJPEGEncodeParam(Raster ras, int colorID)
          This is a factory method for creating JPEGEncodeParam objects.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Method Detail

createJPEGDecoder

public static JPEGImageDecoder createJPEGDecoder(InputStream src)
This creates an instance of a JPEGImageDecoder that can be used to decode JPEG Data streams.

createJPEGDecoder

public static JPEGImageDecoder createJPEGDecoder(InputStream src,
                                                 JPEGDecodeParam jdp)
This creates an instance of a JPEGImageDecoder that can be used to decode JPEG Data streams.

createJPEGEncoder

public static JPEGImageEncoder createJPEGEncoder(OutputStream dest)
This creates an instance of a JPEGImageEncoder that can be used to encode image data as JPEG Data streams.

createJPEGEncoder

public static JPEGImageEncoder createJPEGEncoder(OutputStream dest,
                                                 JPEGEncodeParam jep)
This creates an instance of a JPEGImageEncoder that can be used to encode image data as JPEG Data streams.

getDefaultJPEGEncodeParam

public static JPEGEncodeParam getDefaultJPEGEncodeParam(BufferedImage bi)
This is a factory method for creating JPEGEncodeParam objects. The returned object should do a credible job of encoding the given BufferedImage.
Parameters:
bi - A BufferedImage that is similar to the BufferedImage(s) that will encoded using the returned JPEGEncodeParam object.

getDefaultJPEGEncodeParam

public static JPEGEncodeParam getDefaultJPEGEncodeParam(Raster ras,
                                                        int colorID)
This is a factory method for creating JPEGEncodeParam objects. It is the users responsiblity to match the colorID with the data contained in the Raster. Failure to do so may lead to either poor compression or poor image quality. If you don't understand much about JPEG it is strongly recommended that you stick to the BufferedImage interface.
Parameters:
ras - Raster that is similar to those to be encoded later.
colorID - the COLOR_ID for the encoded data. This should match the data in the raster.

getDefaultJPEGEncodeParam

public JPEGEncodeParam getDefaultJPEGEncodeParam(int numBands,
                                                 int colorID)
                                          throws ImageFormatException
This is a factory method for creating JPEGEncodeParam objects. It is the users responsiblity to match the colorID with the given number of bands, which should match the data being encoded. Failure to do so may lead to poor compression and/or poor image quality. If you don't understand much about JPEG it is strongly recommended that you stick to the BufferedImage interface. This can also be used as a factory for a JPEGDecodeParam object. However this usage is extremely rare, as one needs to be decoding abbreviated JPEG streams where the JPEG tables are coming from some source other than a JPEG tables only stream.
Parameters:
numBands - the number of bands that will be encoded (max of four).
colorID - the COLOR_ID for the encoded data. This is used to set reasonable defaults in the parameter object. This must match the number of bands given.

getDefaultJPEGEncodeParam

public static JPEGEncodeParam getDefaultJPEGEncodeParam(JPEGDecodeParam jdp)
                                                 throws ImageFormatException
This is a factory method for creating a JPEGEncodeParam from a JPEGDecodeParam. This will return a new JPEGEncodeParam object that is initialized from the JPEGDecodeParam object. All major pieces of information will be initialized from the DecodeParam (Markers, Tables, mappings).
Parameters:
jdp - The JPEGDecodeParam object to copy.
com.sun.image.codec.jpeg
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