Validating sources as containing a gain map?

[gregbenz]

Does ultrahdr_app have a feature which might be used simply to validate that an image contains a gain map? For example, this could be useful to triage uploads to a website.

If this isn't supported, please consider this as a feature request for the future to support efficient queries for gain maps natively supported by the project.

[mcDandy]

The app does not have a validation only mode. The library itself however has it as a functions (but my understanding to the library Is very limited) but you cannot use library itself. Dne po 13. 5. 2024 19:35 uživatel Greg B ***@***.***> napsal:

…

Does ultrahdr_app have a feature which might be used simply to validate that an image contains a gain map? For example, this could be useful to triage uploads to a website. If this isn't supported, please consider this as a feature request for the future to support efficient queries for gain maps natively supported by the project. — Reply to this email directly, view it on GitHub <#137>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AEN2KD5I5B52C6GU47WO75DZCD2XZAVCNFSM6AAAAABHUUP64GVHI2DSMVQWIX3LMV43ERDJONRXK43TNFXW4OZWGY3DENJTGU> . You are receiving this because you are subscribed to this thread.Message ID: ***@***.***>

[ram-mohan]

The sample application does not have an option to determine if the image is a valid uhdr. But the library interface exposes functions that can determine the same.

uhdr_codec_private_t* obj = uhdr_create_decoder(); // create decoder
uhdr_compressed_image_t uhdr_image{};
uhdr_image.data = img->data;
uhdr_image.data_sz = img->length;
uhdr_image.capacity = img->length;
uhdr_image.cg = UHDR_CG_UNSPECIFIED;
uhdr_image.ct = UHDR_CT_UNSPECIFIED;
uhdr_image.range = UHDR_CR_UNSPECIFIED;
RET_IF_ERR(uhdr_dec_set_image(obj, &uhdr_image)) // register image
RET_IF_ERR(uhdr_probe(obj)) // probe image
uhdr_release_decoder(obj); // release decoder

[ram-mohan]

If probe call is successful, there are variety of function calls that can be made after probe to get useful data, like

uhdr_dec_get_image_width(obj) returns primary image width
uhdr_dec_get_image_height(obj) returns primary image height
uhdr_dec_get_gainmap_width(obj) returns gainmap image width
uhdr_dec_get_gainmap_height(obj) returns gainmap image height
uhdr_dec_get_gain_map_metadata(obj) returns gainmap metadata

[gregbenz]

@ram-mohan Thank you. What would you recommend as the most performant way to use the above functions to determine that the target had a valid gain map? Ultimately, I would think metadata checks of the parent/auxiliary image would be suitable (ie, check headers/metadata and assume any images present are not corrupt)

[ram-mohan]

uhdr_dec_probe(), checks if there is a valid primary image, gainmap image and valid hdr metadata. If it returns success, then we can assume its a valid uhdr image. Primary image / gainmap image being corrupt (headers are ok, but entropy coded residue data is corrupted) is realized only during actual decode.

uhdr_dec_probe() return status should be a good starting filtering check.

[gregbenz]

Thank you, @ram-mohan !