Ultra HDR support

[cjee21]

Newer Android phones capture images in Ultra HDR.
https://developer.android.com/media/platform/hdr-image-format

Samples: https://www.dpreview.com/sample-galleries/7614427312

[cjee21]

Apple also has it: https://www.androidauthority.com/google-apple-hdr-photo-standard-3495035/

[JeromeMartinez]

I have a HEIC file from iPhone 15 with the gain map stuff (and a grid system, I need to implement that too, I started the grid support), now it needs an implementation... It seems that the HEIC and the JPG implementation are very different, yet other work to do...

[cjee21]

More samples (ISO 21496-1?) here: https://helpx.adobe.com/camera-raw/using/gain-map.html

[JeromeMartinez]

More samples (ISO 21496-1?)

"currently under development."

but there is a start of spec: Gain Map Specification (1.0 draft 15, February 2024)

As a quick check, it is an additional picture + XML metadata, at least in HEIC, I need to find where is the additional picture in the JPEG file.

[cjee21]

Looks like there are multiple formats, the Android Ultra HDR XMP, Adobe XMP, Apple XMP and the under-development ISO 21496-1 that they all are going to support too.

[cjee21]

JPEG uses MPF to store the additional image. I wonder if Sony's old 3D photos also uses this.

[cjee21]

If want to handle MPF, it's IFDs like Exif and TIFF again...

[cjee21]

Sony's 3D photos also uses MPF containing 2 to 15 images.

https://web.archive.org/web/20120123035845/http://www.stereomaker.net/sony/sony.htm

[cjee21]

Found the MPF

00EC51 FFE2 - APP2 - Application-specific marker 2 - Multi-Picture Format (90 bytes)
00EC51  Header (4 bytes)
00EC51   Marker:                               65506 (0xFFE2)
00EC53   Fl - Frame header length:             88 (0x0058)
00EC55  Signature:                             MPF
00EC59  Header (8 bytes)
00EC59   Alignment:                            II*
00EC5D   Offset to first IFD:                  8 (0x00000008)
00EC61  MP Index IFD (2 bytes)
00EC61   Count:                                3 (0x0003)
00EC63  (Not parsed):                          (72 bytes)

[JeromeMartinez]

Found the MPF

Do you plan to do a PR and/or need help?

[cjee21]

Do you plan to do a PR and/or need help?

What's the plan? Another File_MPF_cpp to handle the IFD parsing like Exif?

[JeromeMartinez]

Another File_MPF_cpp to handle the IFD parsing like Exif?

I guess so.
With a public Exif class member for storing offset & size so the JPEG parser can seek to the next image when a SOS is reached.

[cjee21]

Android 16 adds HDR PNGs

https://source.android.com/docs/core/graphics/hdr-screenshots#android16-hdr-shot

I cannot find a sample yet.