[libcamera-devel] [PATCH] android: exif: Contain IMAGE_WIDTH and IMAGE_LENGTH data

[Hirokazu Honda]

Hi Umang, thanks for reviewing,

On Tue, Mar 23, 2021 at 6:04 PM Umang Jain <umang.jain at ideasonboard.com> wrote:
>
> Hi Hiro,
>
> On 3/23/21 1:32 PM, Hirokazu Honda wrote:
> > ChromeOS camera test checks if exif data has the IMAGE_WIDTH and
> > IMAGE_LENGTH and they are the same as the requested jpeg size.
> > This adds the resolution data to exif.
> >
> > Signed-off-by: Hirokazu Honda <hiroh at chromium.org>
> >
> > ---
> >   src/android/jpeg/exif.cpp | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/src/android/jpeg/exif.cpp b/src/android/jpeg/exif.cpp
> > index 922086cd..29c7be0f 100644
> > --- a/src/android/jpeg/exif.cpp
> > +++ b/src/android/jpeg/exif.cpp
> > @@ -286,6 +286,8 @@ void Exif::setModel(const std::string &model)
> >
> >   void Exif::setSize(const Size &size)
> >   {
> > +     setLong(EXIF_IFD_0, EXIF_TAG_IMAGE_LENGTH, size.height);
> > +     setLong(EXIF_IFD_0, EXIF_TAG_IMAGE_WIDTH, size.width);
> I am reading the EXIF spec and for ImageLength and ImageWidth, it states:
>
> ```
> ImageWidth
> The number of columns of image data, equal to the number of pixels per
> row. In JPEG compressed
> data, this tag shall not be used because a JPEG marker is used instead
> of it.
> ```
>
> Same for ImageLength.
>
> We compress the image using JPEG post-processor right? Hence, I think
> these tags shouldn't be applicable (as per spec's point of view).
>

I think you're right.
Our test code [1] seems to come from Android CTS test code [2].
I am asking Android camera people if the check is correct.
I will update here their response.

[1] https://source.chromium.org/chromiumos/chromiumos/codesearch/+/main:src/platform2/camera/camera3_test/camera3_exif_validator.cc;l=337;drc=82fcae1960c0283214607107037c747c0e545617
[2] https://cs.android.com/android/platform/superproject/+/master:cts/tests/camera/utils/src/android/hardware/camera2/cts/CameraTestUtils.java;l=2669;drc=556fa09af46eeb2e8abe418d0f049c154bc4181a

Regards,
-Hiro

> >       setLong(EXIF_IFD_EXIF, EXIF_TAG_PIXEL_Y_DIMENSION, size.height);
> >       setLong(EXIF_IFD_EXIF, EXIF_TAG_PIXEL_X_DIMENSION, size.width);
> >   }
> > --
> > 2.31.0.rc2.261.g7f71774620-goog
> > _______________________________________________
> > libcamera-devel mailing list
> > libcamera-devel at lists.libcamera.org
> > https://lists.libcamera.org/listinfo/libcamera-devel
> --
> Regards,
> Umang Jain
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