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    Ultra HDR Image Format from Google

    Hello. I'd call this a feature request in advance, for the next or even later release of Irfanview.

    The plan of Google developer is to make Ultra HDR Image format the default format for photographs taken with cameras of smartphones starting with Android v14.

    As I understand it, it's an image format based on JPEG with extensions and additional metadata. Because of the additional metadata in the file header existing JPEG decoders can't read such files,
    but I shouldn't be that difficult to read at least the basic JPEG image from the file.

    Format specs here: https://developer.android.com/guide/...r-image-format

    #2
    Originally posted by Winnie2 View Post
    Because of the additional metadata in the file header existing JPEG decoders can't read such files, but it shouldn't be that difficult to read at least the basic JPEG image from the file.
    The very first paragraph of the specification says:

    "Legacy readers that don't support the new format read and display the conventional low dynamic range image from the image file."

    And in the Motivation section, it says:

    "The goal of this file format is to encode additional information in SDR image files that can be used in combination with the display technique to produce their optimal HDR renditions, in a single file.

    For this to be practical, the file format must:
    • Be backward compatible, so that on naive viewers, the conventional SDR image is displayed."
    ‚Äč
    Your statement that "existing JPEG decoders can't read such files" is not correct.

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      #3
      The problem is not the picture itself, it's the structure of the metadata. E.g. the APP1 segment contains EXIF data in established JPEG files from cameras, not in the Ultra HDR image, APP1 contains data about the structure of the picture.
      So I asked myself where to place EXIF data in Ultra HDR image format. EXIF does contain info like picture orientation.

      So the Ultra HDR image might be displayed as a picture but with wrong orientation and without proper EXIF metadata.

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        #4
        Common JPEG files usually contain multiple APP1 segments, one with Exif followed by another one with Photoshop XMP. The lossless operations in IrfanView don't currently discriminate between them. Irfan said maybe later. If the marker exceeds 64K it will be split up. Probably the lossless operations should add this additional type of HDR data. Are there any example files showing a different convention for storing Exif? I don't suppose it's a big deal if the metadata is not available.

        If Google can do this, they could have introduced a transparency channel in JPEG a long time ago.

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