Blurry Thumbnails for Sealife DC2000 DNG Files

Submitted by tjdolan1 on Sun, 11/01/2020 - 10:49
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General discussion

Curious how the thumbnails are generated for viewing in the grid. I shot multiple sessions with a Sealife DC2000 camera that uses a version of the DNG raw format. I saved both the DNG and external JPG images. The embedded JPG (not the external JPG) appears blurry in FRV and it appears that the embedded image is the one displayed in the FRV grid.  Questions: 1) Does this have something to do with the DNG version used by Sealife that is not being properly processed by FRV? and 2) is there a way to diplay the external JPG as a thumbnail in the grid? Thanks.

lexa

Sun, 11/01/2020 - 11:24

Current version of FastRawViewer always prefer embedded preview for thumbnail display (mostly for the speed reason). We'll consider additional option for some future FRV update.

Sealife DC2000 files (downloaded several ones from DPreview) contain 640x480 and 160x120 previews, but metadata section for 640x480 one is damaged (e.g. PreviewImageLength tag value is too smal, about 3000, not possible for 640x480 image).

Could you please share several different samples w/us (use any sharing service and send link to support@fastrawviewer.com), may be your samples are not that damaged.

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Alex Tutubalin/FastRawViewer team

lexa

Sun, 11/01/2020 - 12:00

Followup:  so called '640x480' preview (in files downloaded from DPReview) really contains 160x120 JPEG image (with ~20:1  compression ratio, so very blurry)

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Alex Tutubalin/FastRawViewer team

tjdolan1

Sun, 11/01/2020 - 12:53

Thanks for looking into this. Just sent an email to support with a link to a couple of DNG examples, including the external jpegs.
Regards

LibRaw

Sun, 11/01/2020 - 16:10

Thank you for the files. As expected, previews are corrupt. E-mail answered with more details ;)

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