utils: raspberrypi: ctt: dng_load_image: Work with DNG files from Picamera2
The DNG specification is based on the TIFF file format and recommends storing the raw image data in a SubIFD and the Exif tags in an Exif IFD. Other options are allowed, even if not recommended, such as storing both the raw image data and the Exif data in IFD0, as done by the TIFF/EP specification. libcamera-apps use pyexiv2 to produce DNG files, following the DNG recommendation, while applications based on picamera2 use PiDNG, which adopts the TIFF/EP structure. Why it does so is not currently clear (see https://github.com/schoolpost/PiDNG/issues/65 for discussions on this topic), but as files based on the DNG and TIFF/EP variants exist in the wild, both need to be supported by ctt. Add code to identify which tags are being used, and then load the metadata from the correct tags. Signed-off-by: William Vinnicombe <william.vinnicombe@raspberrypi.com> Reviewed-by: David Plowman <david.plowman@raspberrypi.com> Reviewed-by: Naushir Patuck <naush@raspberrypi.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
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1 changed files with 25 additions and 7 deletions
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@ -301,17 +301,35 @@ def dng_load_image(Cam, im_str):
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metadata.read()
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Img.ver = 100 # random value
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"""
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The DNG and TIFF/EP specifications use different IFDs to store the raw
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image data and the Exif tags. DNG stores them in a SubIFD and in an Exif
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IFD respectively (named "SubImage1" and "Photo" by pyexiv2), while
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TIFF/EP stores them both in IFD0 (name "Image"). Both are used in "DNG"
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files, with libcamera-apps following the DNG recommendation and
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applications based on picamera2 following TIFF/EP.
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This code detects which tags are being used, and therefore extracts the
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correct values.
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"""
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try:
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Img.w = metadata['Exif.SubImage1.ImageWidth'].value
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subimage = "SubImage1"
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photo = "Photo"
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except KeyError:
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Img.w = metadata['Exif.Image.ImageWidth'].value
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subimage = "Image"
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photo = "Image"
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Img.pad = 0
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Img.h = metadata['Exif.SubImage1.ImageLength'].value
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white = metadata['Exif.SubImage1.WhiteLevel'].value
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Img.h = metadata[f'Exif.{subimage}.ImageLength'].value
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white = metadata[f'Exif.{subimage}.WhiteLevel'].value
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Img.sigbits = int(white).bit_length()
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Img.fmt = (Img.sigbits - 4) // 2
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Img.exposure = int(metadata['Exif.Photo.ExposureTime'].value*1000000)
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Img.againQ8 = metadata['Exif.Photo.ISOSpeedRatings'].value*256/100
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Img.exposure = int(metadata[f'Exif.{photo}.ExposureTime'].value * 1000000)
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Img.againQ8 = metadata[f'Exif.{photo}.ISOSpeedRatings'].value * 256 / 100
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Img.againQ8_norm = Img.againQ8 / 256
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Img.camName = metadata['Exif.Image.Model'].value
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Img.blacklevel = int(metadata['Exif.SubImage1.BlackLevel'].value[0])
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Img.blacklevel = int(metadata[f'Exif.{subimage}.BlackLevel'].value[0])
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Img.blacklevel_16 = Img.blacklevel << (16 - Img.sigbits)
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bayer_case = {
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'0 1 1 2': (0, (0, 1, 2, 3)),
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@ -319,7 +337,7 @@ def dng_load_image(Cam, im_str):
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'2 1 1 0': (2, (3, 2, 1, 0)),
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'1 0 2 1': (3, (1, 0, 3, 2))
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}
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cfa_pattern = metadata['Exif.SubImage1.CFAPattern'].value
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cfa_pattern = metadata[f'Exif.{subimage}.CFAPattern'].value
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Img.pattern = bayer_case[cfa_pattern][0]
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Img.order = bayer_case[cfa_pattern][1]
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