JPEG2000 Transparency with JasPer Library

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I'm attempting to use JasPer JPEG2000 library to create transparent JPEG2000 images (actually I'm creating JPCs).

The issue I'm having is that I can't figure out how to make JasPer create a transparency image. None of its supported formats support transparency (with the exception of the JPEG2000 formats, which are what I'm trying to create):

The following formats are supported:
    mif      My Image Format (MIF)
    pnm      Portable Graymap/Pixmap (PNM)
    bmp      Microsoft Bitmap (BMP)
    ras      Sun Rasterfile (RAS)
    jp2      JPEG-2000 JP2 File Format Syntax (ISO/IEC 15444-1)
    jpc      JPEG-2000 Code Stream Syntax (ISO/IEC 15444-1)
    jpg      JPEG (ISO/IEC 10918-1)
    pgx      JPEG-2000 VM Format (PGX)

In the JasPer documentation it uses the word "transparency" once in this context:

A RGBA (i.e., RGB with transparency) image would have four components, one associated with each of the red, green, blue, and alpha planes. The various components need not be sampled at the same resolution. In other words, different components may have different sampling periods. For example, when color images are represented in a luminance-chrominance color space, it is not uncommon for the luminance information to be more finely sampled than the chrominance information

That implies that transparency is supported, since it is discussing how transparency works in the encoding. And yet... how to use it?

Any ideas?

Also any other open-source alternative that supports the creation of transparent JPCs would be good.

Thanks.

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