Implementing JPEG 2000 Features

JPEG 2000 is a wavelet based compression stored in a hierarchical format which contains several stored resolutions of the image in the same file without duplication. For that reason, a JPEG 2000 compressed image can then be sent to a device in the resolution that best fits, without additional storage overhead.

LEADTOOLS provides support for loading and saving the JPEG 2000 file formats. The JPEG 2000 file formats provide greater flexibility and better image quality, especially at higher compression, than standard JPEG. The greater flexibility includes the ability to control:

whether or not to transform RGB images to YUV prior to compression
the type of quantization to use when determining the quantization step size
the amount of compression
the size and location of tiles
the number of resolution levels in the file
the progression order
the code block height and width
whether to use markers to help detect corruption during transmission
etc.

LEADTOOLS provides a several properties for controlling the JPEG 2000 features listed above. These properties are:

J2KCBS_ErrorResilienceSymbol property

J2KCBS_PredictableTermination property

J2KCBS_ResetContextOnBoundaries property

J2KCBS_SelectiveACBypass property

J2KCBS_TerminationOnEachPass property

J2KCBS_VerticallyCausalContext property

J2KCodBlockHeight property

J2KCodBlockWidth property

J2KCompressionControl property

J2KCompressionRatio property

J2KDecompLevel property

J2KDerivedBaseExponent property

J2KDerivedBaseMantissa property

J2KDerivedQuantization property

J2KGuardBits property

J2KProgressOrder property

J2KSetDefaults method

J2KTargetFileSize property

J2KUseColorTransform property

J2KUseEPHMarker property

J2KUseSOPMarker property

To update the properties listed above with the default values used when saving a JPEG 2000 file, call the J2KSetDefaults method. To change the JPEG 2000 features, set the properties themselves.

A region of interest can now be used for a J2K image. The J2KUseROI property indicates whether or not to use a region of interest. If this is TRUE, then the region of interest is defined based on the J2KROIControl property. If the J2KUseROI property is TRUE and the J2KROIControl property is set to J2K_USELEAD_REGION, then the region of interest is designated by the LEAD bitmap region. If the J2KUseROI property is TRUE and the J2KROIControl property is set to J2K_USEOPTION_RECT, then the region of interest is designated by the rectangle defined by the J2KROILeft, J2KROITop, J2KROIHeight, and J2KROIWidth properties.