[PATCH 2/3] apps: common: dng_writer: Add thumbnail scanline function for RawXX

[David Plowman]

Hi Stefan

On Thu, 27 Jun 2024 at 15:02, Stefan Klug <stefan.klug at ideasonboard.com> wrote:
>
> Hi David,
>
> On Thu, Jun 27, 2024 at 02:27:57PM +0100, David Plowman wrote:
> > Hi Stefan
> >
> > Looks good to me!
>
> Thanks
>
> >
> > On Thu, 27 Jun 2024 at 13:53, Stefan Klug <stefan.klug at ideasonboard.com> wrote:
> > >
> > > Add a thumbnail function for raw formats that are 16bit aligned.
> > > This is needed for the upcoming RAW10 and RAW12 implemntation.
> > >
> > > Use the new function for RAW16 as the thumbScanlineRawXX_CSI2P produces
> > > incorrect results for that format (it averages over adjacent bytes,
> > > which works for the CSI formats).
> > >
> > > Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
> > > ---
> > >  src/apps/common/dng_writer.cpp | 32 ++++++++++++++++++++++++++++----
> > >  1 file changed, 28 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/src/apps/common/dng_writer.cpp b/src/apps/common/dng_writer.cpp
> > > index 88b225d3e099..2cb320ff327b 100644
> > > --- a/src/apps/common/dng_writer.cpp
> > > +++ b/src/apps/common/dng_writer.cpp
> > > @@ -144,6 +144,30 @@ void packScanlineRaw16(void *output, const void *input, unsigned int width)
> > >         std::copy(in, in + width, out);
> > >  }
> > >
> > > +/* Thumbnail function for raw data aligned to 16bit words */
> > > +void thumbScanlineRawXX(const FormatInfo &info, void *output,
> > > +                         const void *input, unsigned int width,
> > > +                         unsigned int stride)
> > > +{
> > > +       const uint16_t *in = static_cast<const uint16_t *>(input);
> > > +       const uint16_t *in2 = static_cast<const uint16_t *>(input) + stride / 2;
> > > +       uint8_t *out = static_cast<uint8_t *>(output);
> > > +
> > > +       /* shift down to 8 */
> > > +       unsigned int shift = info.bitsPerSample - 8;
> > > +
> > > +       /* simple averaging that produces grey RGB values */
> > > +       for (unsigned int x = 0; x < width; x++) {
> > > +               uint16_t value = (in[0] + in[1] + in2[0] + in2[1]) >> 2;
> > > +               value = value >> shift;
> > > +               *out++ = value;
> > > +               *out++ = value;
> > > +               *out++ = value;
> >
> > Just a small question as to whether you might want to subtract some
> > black level and apply some "fake" gamma? It might make the thumbnails
> > look a bit nicer. But just a matter of taste, I think, not something
> > I'd worry over!
>
> That would surely be nicer. I'd also like to have some colors in there.
> Do you see the thumbnails a lot? I actually had to dig where the
> thumbnails get displayed (in my case only the overview in RawTherapy)
> because in my daily use I never saw them.

Colours are more of a hassle because you have white balance and a
colour matrix to apply. You have all the information so it's doable.
But I think it's mostly a question of whether you can be bothered...

There are indeed ever fewer places where a thumbnail seems necessary.
Some older versions of operating systems maybe, but these days not so
much. So not changing anything at all seems fair enough to me!

David

>
> Cheers,
> Stefan
>
> >
> > David
> >
> > > +               in += 16;
> > > +               in2 += 16;
> > > +       }
> > > +}
> > > +
> > >  void packScanlineRaw10_CSI2P(void *output, const void *input, unsigned int width)
> > >  {
> > >         const uint8_t *in = static_cast<const uint8_t *>(input);
> > > @@ -321,25 +345,25 @@ const std::map<PixelFormat, FormatInfo> formatInfo = {
> > >                 .bitsPerSample = 16,
> > >                 .pattern = { CFAPatternBlue, CFAPatternGreen, CFAPatternGreen, CFAPatternRed },
> > >                 .packScanline = packScanlineRaw16,
> > > -               .thumbScanline = thumbScanlineRawXX_CSI2P,
> > > +               .thumbScanline = thumbScanlineRawXX,
> > >         } },
> > >         { formats::SGBRG16, {
> > >                 .bitsPerSample = 16,
> > >                 .pattern = { CFAPatternGreen, CFAPatternBlue, CFAPatternRed, CFAPatternGreen },
> > >                 .packScanline = packScanlineRaw16,
> > > -               .thumbScanline = thumbScanlineRawXX_CSI2P,
> > > +               .thumbScanline = thumbScanlineRawXX,
> > >         } },
> > >         { formats::SGRBG16, {
> > >                 .bitsPerSample = 16,
> > >                 .pattern = { CFAPatternGreen, CFAPatternRed, CFAPatternBlue, CFAPatternGreen },
> > >                 .packScanline = packScanlineRaw16,
> > > -               .thumbScanline = thumbScanlineRawXX_CSI2P,
> > > +               .thumbScanline = thumbScanlineRawXX,
> > >         } },
> > >         { formats::SRGGB16, {
> > >                 .bitsPerSample = 16,
> > >                 .pattern = { CFAPatternRed, CFAPatternGreen, CFAPatternGreen, CFAPatternBlue },
> > >                 .packScanline = packScanlineRaw16,
> > > -               .thumbScanline = thumbScanlineRawXX_CSI2P,
> > > +               .thumbScanline = thumbScanlineRawXX,
> > >         } },
> > >         { formats::SBGGR10_CSI2P, {
> > >                 .bitsPerSample = 10,
> > > --
> > > 2.43.0
> > >