MOS to JPEG Converter
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Supports: MOS
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Need help?MOS to JPEG Converter
MOS is the Leaf RAW format written by Leaf Aptus and Mamiya medium-format digital backs — sensor data with no in-camera processing, openable mainly in Capture One, Leaf Capture, Lightroom, or Photoshop. Converting to JPEG renders that RAW into a standard 8-bit photo that opens in any browser, viewer, or editor, at a fraction of the original file size.
MOS Format at a Glance
| Property | Value |
|---|---|
| Type | Camera RAW (sensor data, undeveloped) |
| Origin | Leaf — formerly a division of Scitex, then Kodak, now part of Phase One |
| Cameras | Leaf Aptus / Aptus-II digital backs; Mamiya medium-format bodies |
| Container | TIFF-based (one variant is uncompressed; another stores the data with lossless JPEG compression) |
| Color depth | 16 bits per channel (e.g. the 80 MP Aptus-II 80 captures 10,320 × 7,752 px at 16-bit) |
| Typical file size | Large — roughly 40 MB to 165 MB per frame depending on the back and compression |
| Opens in | Capture One, Leaf Capture, Adobe Lightroom, Photoshop / Camera Raw |
| Best for | Archiving the full latitude of a medium-format capture before editing |
JPEG Format at a Glance
| Property | Value |
|---|---|
| Type | Compressed raster photo (developed, not RAW) |
| Standard | JPEG / JFIF, DCT-based lossy compression |
| Color depth | 8 bits per channel, RGB true color |
| File size | Far smaller than MOS — a single high-MP frame typically lands in the low single-digit to low double-digit megabytes |
| Native support | Every major browser (Chrome, Edge, Firefox, Opera, Safari) and effectively all image software |
| Best for | Sharing, web, previews, and anything that needs to open everywhere |
How to Convert MOS to JPEG
- Upload Your MOS File: Drag and drop your
.mosfile onto the page or click "+ Add Files" to browse. You can queue several frames and convert them with the same settings. - Pick a Quality Preset: Choose an Image Compression / Quality Preset — "Very High" is the default and keeps the most detail; lower presets trade sharpness for a smaller JPEG.
- Set Image Resolution (Optional): Leave "Keep original" to render at the back's full pixel dimensions, or use Resolution Percentage / Preset Resolutions / Width × Height to scale down for the web.
- Convert and Download: Click "Convert" and download the JPEG. No sign-up, no watermark. Files are uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours after conversion.
Frequently Asked Questions
Will I lose editing latitude converting MOS to JPEG?
Yes — and that is the nature of the conversion. A MOS file holds undeveloped 16-bit sensor data with wide exposure and white-balance headroom. JPEG bakes those decisions in and stores the result as an 8-bit image, so you lose the ability to recover highlights, push shadows, or re-balance color the way you can on the RAW. Keep the original MOS if you may need to re-edit; use the JPEG for sharing and viewing.
How large will the JPEG be compared to the MOS file?
Much smaller. A single MOS frame can run from roughly 40 MB to over 160 MB depending on the digital back and whether it was stored compressed. The rendered JPEG of the same image is usually in the single-digit to low double-digit megabyte range at high quality, because JPEG uses lossy DCT compression and discards the RAW overhead. Lowering the Quality Preset or scaling the resolution shrinks it further.
Does the JPEG keep the full resolution of the medium-format capture?
It can. By default the conversion renders at the back's native pixel dimensions — for example the 80 MP Aptus-II 80 produces a 10,320 × 7,752 px image, and the JPEG will match that unless you scale it down. At full size the JPEG stays large and sharp; if you only need a web preview, set Resolution Percentage or pick a smaller preset resolution.
Why convert MOS at all instead of just opening it?
MOS is a proprietary Leaf RAW format. Outside of Capture One, Leaf Capture, and recent Lightroom or Photoshop builds, most viewers, browsers, and editors cannot open it. Converting to JPEG turns the file into a universally supported photo so you can email it, post it, or drop it into software that has never heard of Leaf's format.
Is MOS the same as a TIFF file?
It is built on the TIFF container but is not an ordinary TIFF. MOS stores camera RAW sensor data inside a TIFF-based structure — one variant is uncompressed, another uses lossless JPEG compression internally — together with Leaf-specific metadata. A standard image program reading it as a plain TIFF will usually fail or show only an embedded preview, which is why a dedicated RAW render to JPEG gives a correct result.
Does converting to JPEG strip the photo's metadata?
The pixels are fully rendered, but RAW-specific Leaf metadata (the data Capture One uses to re-develop the file) is not meaningful in a JPEG and is not carried over. Standard EXIF-style fields such as capture settings may be preserved where present. If you need the original sensor data and full metadata, retain the MOS file alongside the JPEG.
What quality setting should I use?
For archival or print, keep the "Very High" preset and full resolution so the render preserves as much of the medium-format detail as possible. For web or email, a lower Quality Preset plus a resolution reduction produces a much smaller file with little visible loss at typical viewing sizes. In our testing, rendering a Leaf MOS at the "Very High" preset and full resolution yields a sharp 8-bit JPEG only a fraction of the original RAW's size, while dropping to a mid preset roughly halves it again.
If you are working with other RAW or photo formats, see our TIFF to JPG converter for flattening TIFF-based images, or JPG to PNG when you need a lossless output instead.