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Support Kodak IFD MakerNote #1952

Open PeterWem opened 2 years ago

PeterWem commented 2 years ago

Exiftool finds ISO without any issue.

Kodak DCS 520 outputs raw files with .TIF To be able to open them in RawTherapee or darktable, change .TIF to .DCR 23HK3655.zip The sample files have ISO 1600 (23HK3658) and ISO 200 (23HK3659).

https://exiftool.org/TagNames/Kodak.html 0x1784 | ISO

postscript-dev commented 2 years ago

Exiv2 does not currently support any Kodak makernote tags. The lists of supported tags for other camera types can be found here.

@PeterWem: Although you are only asking for one tag to be added, which is usually a simple task, the infrastructure to process the Kodak makernotes has not been created. This makes the job bigger. I don't have time to work on this myself, sorry.

kmilos commented 2 years ago

"ISO" can actually be read from these images from the standard Exif.Image.ExposureIndex:

$ exiv2 -Pkt -g ExposureIndex 23HK3658.TIF
Exif.Image.ExposureIndex                      1600/1
$ exiv2 -Pkt -g ExposureIndex 23HK3659.TIF
Exif.Image.ExposureIndex                      200/1

From the TIFF/EP standard Kodak files claim they're adhering to:

The exposure index setting of the camera used to capture the image is encoded in the ExposureIndex tag-field as a RATIONAL value. For example, an exposure index of 100 is encoded as 100/1. ISO/TC42/WG18 Working Draft 6.0, “Photography - Electronic still picture cameras - Determination of ISO speed” shall be used in determining the exposure index value. An exposure index is a numerical value that is inversely proportional to the exposure provided to an image sensor to obtain an image. Images obtained from a camera using a range of exposure index values will normally provide a range of image quality levels. The ISO speed ratings of the electronic still camera are two values calculated from the exposure provided at the focal plane of an electronic camera and the camera output signal characteristics. The two ratings are the “Saturation based” ISO speed rating and the “Noise based” ISO speed rating. These values are encoded in the ISOSpeedRatings tag-field as short values.

We are missing this from our isoSpeed() easy accessor though (but we do have a separate exposureIndex() one).

They are not always the same thing and I guess it is correct it is not included in isoSpeed(). For this Kodak camera, they are used interchangeably (same value as in the Kodak MakerNote ISO tag).

I suggest closing this a non-bug, or change the title to general Kodak MakerNote support.

PeterWem commented 2 years ago

I see and I understand.