Interface ImageTranscoder
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- All Known Implementing Classes:
- ImageWriter
public interface ImageTranscoderAn interface providing metadata transcoding capability.Any image may be transcoded (written to a different format than the one it was originally stored in) simply by performing a read operation followed by a write operation. However, loss of data may occur in this process due to format differences.
In general, the best results will be achieved when format-specific metadata objects can be created to encapsulate as much information about the image and its associated metadata as possible, in terms that are understood by the specific
ImageWriterused to perform the encoding.An
ImageTranscodermay be used to convert theIIOMetadataobjects supplied by theImageReader(representing per-stream and per-image metadata) into corresponding objects suitable for encoding by a particularImageWriter. In the case where the methods of this interface are being called directly on anImageWriter, the output will be suitable for that writer.The internal details of converting an
IIOMetadataobject into a writer-specific format will vary according to the context of the operation. Typically, anImageWriterwill inspect the incoming object to see if it implements additional interfaces with which the writer is familiar. This might be the case, for example, if the object was obtained by means of a read operation on a reader plug-in written by the same vendor as the writer. In this case, the writer may access the incoming object by means of its plug-in specific interfaces. In this case, the re-encoding may be close to lossless if the image file format is kept constant. If the format is changing, the writer may still attempt to preserve as much information as possible.If the incoming object does not implement any additional interfaces known to the writer, the writer has no choice but to access it via the standard
IIOMetadatainterfaces such as the tree view provided byIIOMetadata.getAsTree. In this case, there is likely to be significant loss of information.An independent
ImageTranscoderessentially takes on the same role as the writer plug-in in the above examples. It must be familiar with the private interfaces used by both the reader and writer plug-ins, and manually instantiate an object that will be usable by the writer. The resulting metadata objects may be used by the writer directly.No independent implementations of
ImageTranscoderare provided as part of the standard API. Instead, the intention of this interface is to provide a way for implementations to be created and discovered by applications as the need arises.
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method and Description IIOMetadataconvertImageMetadata(IIOMetadata inData, ImageTypeSpecifier imageType, ImageWriteParam param)Returns anIIOMetadataobject that may be used for encoding and optionally modified using its document interfaces or other interfaces specific to the writer plug-in that will be used for encoding.IIOMetadataconvertStreamMetadata(IIOMetadata inData, ImageWriteParam param)Returns anIIOMetadataobject that may be used for encoding and optionally modified using its document interfaces or other interfaces specific to the writer plug-in that will be used for encoding.
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Method Detail
convertStreamMetadata
IIOMetadata convertStreamMetadata(IIOMetadata inData, ImageWriteParam param)
Returns anIIOMetadataobject that may be used for encoding and optionally modified using its document interfaces or other interfaces specific to the writer plug-in that will be used for encoding.An optional
ImageWriteParammay be supplied for cases where it may affect the structure of the stream metadata.If the supplied
ImageWriteParamcontains optional setting values not understood by this writer or transcoder, they will be ignored.- Parameters:
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inData- anIIOMetadataobject representing stream metadata, used to initialize the state of the returned object. -
param- anImageWriteParamthat will be used to encode the image, ornull. - Returns:
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an
IIOMetadataobject, ornullif the plug-in does not provide metadata encoding capabilities. - Throws:
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IllegalArgumentException- ifinDataisnull.
convertImageMetadata
IIOMetadata convertImageMetadata(IIOMetadata inData, ImageTypeSpecifier imageType, ImageWriteParam param)
Returns anIIOMetadataobject that may be used for encoding and optionally modified using its document interfaces or other interfaces specific to the writer plug-in that will be used for encoding.An optional
ImageWriteParammay be supplied for cases where it may affect the structure of the image metadata.If the supplied
ImageWriteParamcontains optional setting values not understood by this writer or transcoder, they will be ignored.- Parameters:
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inData- anIIOMetadataobject representing image metadata, used to initialize the state of the returned object. -
imageType- anImageTypeSpecifierindicating the layout and color information of the image with which the metadata will be associated. -
param- anImageWriteParamthat will be used to encode the image, ornull. - Returns:
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an
IIOMetadataobject, ornullif the plug-in does not provide metadata encoding capabilities. - Throws:
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IllegalArgumentException- if either ofinDataorimageTypeisnull.
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