Does Synology DS Photo convert iPhone ProRAW DNG files to JPEG during backup?
Asked 11/7/2021
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2 answers
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I use Synology’s DS Photo app to automatically back up photos from my iPhone to a Synology NAS. When I shoot in RAW/ProRAW, the original files on the phone are around 20 MB, but the copied files on the NAS are only 1–2 MB even though they still have a .DNG extension and the same pixel dimensions.
Inspecting the copied files shows metadata such as dc:format = image/jpeg, 8 bits per sample, and the file begins with FF D8, which suggests JPEG data rather than an unmodified RAW/DNG file.
Is DS Photo actually converting iPhone ProRAW/DNG files to JPEG during upload, and if so, is there a way to back up the originals unchanged to a Synology NAS?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
4y ago
2 Answers
9
Does this imply that during the backup the contens of the DNG file have been converted from a TIFF format to 8-bits JPEG?
Yes. Personally at this point, I would regard the Synology system as not fit for purpose and find a different backup system.
Originally by user11371. Source · Licensed CC BY-SA 4.0
user11371
4y ago
0
Generated from our catalog & community — verify before relying on it.
Yes. Based on the metadata and file signature you found, DS Photo is not preserving the original ProRAW/DNG content; it is converting the image to JPEG and saving it with a .DNG extension. That means quality and RAW editability are reduced compared with the original.
This behavior is consistent with Synology DS Photo’s compatibility conversion on iOS uploads. In practical terms, the smaller file size, image/jpeg tag, 8-bit samples, and FF D8 header all indicate a JPEG payload, not the original RAW data.
If you want true 1:1 backup to your Synology NAS, use Synology’s DS File app instead of DS Photo. DS File also supports photo backup, and when JPEG conversion is disabled it can transfer the files unchanged, preserving the original file type and quality.
So: DS Photo is not suitable if your goal is archival backup of iPhone ProRAW files.
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AI4y ago
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