can decode api to extract gain map metadata only?

[GrousexyHKCN]

is it possible to extract the gain map metadata then save to file?

[ram-mohan]

You can use uhdr_dec_get_gain_map_metadata() to get metadata. The return value is of type uhdr_gainmap_metadata_t. You can write the fields to a file.

[pmonck]

Could this functionality be added to the demo app? It would be great to be able to extract, edit and copy metadata between ultrahdr jpegs.

[ram-mohan]

will try to add a pull request to handle this. Thank you,
For urgent purposes, Below code should work,

uhdr_codec_private_t* handle = uhdr_create_decoder();
RET_IF_ERR(uhdr_dec_set_image(handle, &mUhdrImage))
RET_IF_ERR(uhdr_dec_probe(handle)) // RET_IF_ERR(uhdr_decode(handle)) also works but for just metadata probe is enough
uhdr_gainmap_metadata_t* metadata = uhdr_dec_get_gain_map_metadata(handle);
// write fields of metadata descriptor to a file.
uhdr_release_decoder(handle);

[ram-mohan]

@pmonck @GrousexyHKCN the demo app contains the changes that supports this.