[PATCH] apps: common: dng_writer: Workaround for "Unknown tag 33421" error

[Stefan Klug]

Hi Laurent,


On Tue, Jun 25, 2024 at 11:43:48AM +0300, Laurent Pinchart wrote:
> Hi Stefan,
> 
> Thank you for the patch.
> 
> On Tue, Jun 25, 2024 at 10:01:11AM +0200, Stefan Klug wrote:
> > In libtiff version 4.5.1 and later the CFA* tags were missing. This got
> > fixed in https://gitlab.com/libtiff/libtiff/-/commit/49856998c3d82e65444b47bb4fb11b7830a0c2be
> > Unfortunately the fix is not released yet, but the faulty libtiff is
> > contained in current buildroot. As a local fix is pretty easy and
> > without side effects, let's workaround that.
> > 
> > Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
> > ---
> >  src/apps/common/dng_writer.cpp | 17 +++++++++++++++++
> >  1 file changed, 17 insertions(+)
> > 
> > diff --git a/src/apps/common/dng_writer.cpp b/src/apps/common/dng_writer.cpp
> > index 103e5c828c4d..7375577e920f 100644
> > --- a/src/apps/common/dng_writer.cpp
> > +++ b/src/apps/common/dng_writer.cpp
> > @@ -541,6 +541,23 @@ int DNGWriter::write(const char *filename, const Camera *camera,
> >  
> >  	TIFFWriteDirectory(tif);
> >  
> > +	/*
> > +	 * Workaround for a bug introduced in libtiff version 4.5.1 and no fix
> > +	 * released. In these versions the CFA* tags were missing in the field
> > +	 * info.
> > +	 * Introduced by: https://gitlab.com/libtiff/libtiff/-/commit/738e04099b13192bb1f654e74e9b5829313f3161
> > +	 * Fixed by: https://gitlab.com/libtiff/libtiff/-/commit/49856998c3d82e65444b47bb4fb11b7830a0c2be
> > +	 */
> > +	if (!TIFFFindField(tif, TIFFTAG_CFAREPEATPATTERNDIM, TIFF_ANY)) {
> > +		static const TIFFFieldInfo infos[] = {
> > +			{ TIFFTAG_EP_CFAREPEATPATTERNDIM, 2, 2, TIFF_SHORT, FIELD_CUSTOM,
> > +			  1, 0, const_cast<char *>("EP CFARepeatPatternDim") },
> > +			{ TIFFTAG_EP_CFAPATTERN, -1, -1, TIFF_BYTE, FIELD_CUSTOM,
> > +			  1, 1, const_cast<char *>("EP CFAPattern") },
> 
> This will fail to compile with libtiff versions older than v4.5.1, where
> the bug was introduced. TIFFTAG_CFAREPEATPATTERNDIM and
> TIFFTAG_CFAPATTERN became aliases for TIFFTAG_EP_CFAREPEATPATTERNDIM and
> TIFFTAG_EP_CFAPATTERN in that version, so I think you can switch to
> TIFFTAG_CFAREPEATPATTERNDIM and TIFFTAG_CFAPATTERN here. I would also
> change the description string to drop the "EP " prefix.

Oh damn, how could I miss that. You are so right.

Cheers,
Stefan

> 
> With that,
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> 
> > +		};
> > +		TIFFMergeFieldInfo(tif, infos, 2);
> > +	}
> > +
> >  	/* Create a new IFD for the RAW image. */
> >  	const uint16_t cfaRepeatPatternDim[] = { 2, 2 };
> >  	const uint8_t cfaPlaneColor[] = {
> 
> -- 
> Regards,
> 
> Laurent Pinchart