Convert MOS to APNG Online

Turning Leaf MOS Captures Into an APNG: What This Covers

MOS is the Creo/Leaf "Mosaic" RAW format — a TIFF-based container written by Leaf medium-format digital backs, carrying Leaf maker-note metadata alongside the sensor data (Phase One's sibling format is IIQ). This page renders those RAW captures and assembles them into an Animated PNG: a lossless, full-colour animation format that is now part of the official PNG specification.

This guide covers the part people get wrong first — an APNG needs more than one image. Upload a single MOS and you get a plain static PNG back, because the animation control chunk that makes a PNG an APNG only exists once there is a sequence to animate. Upload your product-turntable or timelapse frames together and they animate.

How to Convert MOS to APNG

1. Upload Your MOS Files in Shooting Order: Drag the captures onto the page or click "+ Add Files". The order you add them is the order they play back in, so sort before you upload rather than after.
2. Set the Video Framerate: The Framerate dropdown drives playback speed. It defaults to 10 FPS (Recommended) and runs from 1 FPS (Slideshow) up to 50 FPS (Max Speed) — 2 to 5 FPS suits a construction or studio timelapse, 24 to 30 FPS suits a turntable that should look like motion.
3. Choose Combine? and Image resolution: Single animation is the default and merges every upload into one APNG; Individual files converts each capture separately. Image resolution starts on Keep original, so switch to Preset Resolutions, Width (Keep aspect ratio) or Width x Height to bring medium-format frames down to a sensible web size.
4. Convert and Download: Click Convert and save the APNG. Files upload over an encrypted connection, are processed on our servers, and are deleted automatically after a few hours. No sign-up, no watermark.

Walk-through: Frame Count, Order, and Speed

Three decisions determine what you get back, and none of them can be fixed after the fact without re-running the conversion.

• Frame count decides whether it animates at all. The PNG specification marks an animated file with an animation control (acTL) chunk that appears before the image data. With one source image there is nothing to animate, so the output is an ordinary static PNG that any viewer opens. Two or more captures produce a real APNG.
• Order is upload order. There is no re-ordering control on this page. If your back wrote sequential filenames, add the files in that sorted order; if you shot brackets or re-takes interleaved with keepers, weed them out before uploading rather than hoping the converter guesses.
• Frame rate is global, not per frame. Every frame gets the same duration. APNG itself supports per-frame delays, but this page exposes one Framerate value, so a sequence that should pause on one hero frame needs to be built in an animation tool instead.
• Resolution is your only size lever here. There is no quality slider, palette control or target-size field on this conversion — APNG is lossless, so the file size follows directly from pixel dimensions and frame count. A full-resolution medium-format sequence makes an enormous file; the Preset Resolutions dropdown sets a height and lets width follow the source aspect ratio.

Common Errors and How to Fix Them

• "I got a still PNG, not an animation" — only one image was in the job. Add every frame of the sequence to the same conversion, with Combine? set to Single animation.
• "The frames play in the wrong order" — the upload order became the playback order. Remove the files and re-add them in sequence.
• "The APNG is hundreds of megabytes" — you kept full medium-format resolution across many frames of a lossless format. Downscale under Image resolution first; halving the height quarters the pixel count per frame.
• "The animation is a slideshow / a blur" — the Framerate value applies to every frame equally. Drop to 2–5 FPS for a deliberate timelapse feel, raise to 24–30 FPS for smooth motion.
• "My upload shows no thumbnail" — several RAW extensions have no preview renderer in the upload list, so you may see a placeholder rather than the image. The conversion itself is unaffected; check the file names.
• "Colours don't match my editor" — the RAW is demosaiced and given a standard tone curve to produce a viewable image. Your own white balance, curve and lens corrections live in your editor's sidecar files and are not applied here. Export developed TIFFs or PNGs from your editor first if the look matters.

APNG vs GIF for Medium-Format Frames

For a smaller, more universally embeddable animation from the same captures, use MOS to GIF instead and accept the palette limit.

What This Page Actually Controls

Frequently Asked Questions

Why did my single MOS file come out as a still image?

Because an animation needs frames. A PNG only becomes an APNG when it carries the animation control chunk that the PNG specification requires, and a one-image job has nothing to animate — so the converter writes a normal static PNG. That is still a perfectly good result if you only wanted the RAW rendered; add two or more captures whenever you want motion.

How do I control which frame plays first?

Upload order. The first file you add becomes the first frame, so arrange the sequence before you drop the files in. There is no drag-to-reorder control after upload, and no filename-based sorting step, which makes it worth naming and sorting your exports on disk first.

What frame rate should I choose for a product turntable?

If you shot a turntable in even angular steps, pick a rate that matches how fast you want the object to spin: 24 or 30 FPS reads as smooth motion, while 10 FPS — the default — gives the slightly stepped look common in e-commerce spin viewers. Timelapses of a set build or a paint-drying sequence generally look better at 2 to 5 FPS, where each frame is meant to register as a distinct state.

Does the converter apply my Capture One or Leaf back adjustments?

No. The MOS is demosaiced and given a standard tone curve so it can be rendered as a viewable image, which is genuine RAW development, but it is not your development. White balance tweaks, curves, spot removal and lens profiles stored by your editor are not read. If the frames have to match a graded look, export finished images from your editor and animate those.

Is APNG lossless, and does the animation degrade my frames?

APNG is lossless — the same compression family as PNG, with no quality parameter to lower and no generation loss when the file is re-saved. The transition that does cost you something is the RAW render itself: a high-bit-depth MOS is rendered to 8 bits per channel for display, which keeps the visible detail but not the editing latitude. Keep the MOS originals as your masters; if you only want one rendered still per capture rather than an animation, use MOS to PNG with the Quality Preset set to Highest, which is the true-colour lossless setting.

Which browsers and apps play APNG?

Support sits at roughly 96% of users globally, including Chrome 59+, Firefox, Safari 8+, and Edge 79+. The format's built-in fallback is the reason it is safe to use anyway: the PNG specification states that a non-animated PNG decoder "will ignore the ancillary APNG-specific chunks and display the static image," so an old viewer or a printer shows your first frame rather than an error.

Why is my APNG so much larger than a video of the same sequence?

Because it is lossless and has no inter-frame motion compensation of the kind a video codec uses. Every frame is stored in full, compressed the way a PNG is. That is exactly what you want for a short loop with crisp edges and clean gradients, and exactly what you do not want for a hundred medium-format frames. Downscale first, trim the sequence to the frames that matter, or convert to a video with MOS to MP4 for long sequences.

Can I make the APNG's background transparent?

Only if the source frames have transparency, and RAW captures do not — a MOS holds sensor data with no alpha channel, so the rendered frames are fully opaque. APNG can carry an 8-bit alpha channel, so if you need a cut-out product spin, mask the frames in an editor, export them as PNGs, and animate those instead.

Should I use GIF instead of APNG?

Use GIF when maximum compatibility and small size beat colour fidelity — chat platforms, ancient email clients, forums that reject other formats. Use APNG when the frames contain smooth gradients, subtle skin tones, or a seamless backdrop, which is most medium-format work: 256 colours will band visibly where 24-bit colour will not.

What happens to my files after the conversion?

Your MOS captures are uploaded over an encrypted connection, processed on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared or made public. We assemble frames strictly in the order you uploaded them, and because APNG is a lossless format, the only levers on this page that change the output are frame rate and pixel dimensions.