Convert ERF to APNG Online

Convert ERF to APNG

ERF is Epson RAW Format, the "digital negative" written by the Epson R-D1 rangefinder line and by nothing else. APNG is Animated PNG — a frame-based extension of PNG that keeps full 24-bit colour, unlike GIF's 256-colour palette. This converter renders the Epson raw sensor data into ordinary RGB frames and assembles them into a single looping APNG: one ERF gives you a plain static PNG, a stack of ERFs gives you an animation in upload order.

ERF Format at a Glance

APNG Format at a Glance

How to Convert ERF to APNG

1. Upload Your ERF Files: Drag and drop your .erf files onto the page or click "+ Add Files". Upload order is playback order, so add the frames in the sequence you want them shown.
2. Set the Framerate: Under "Framerate", the dropdown is preselected to "10 FPS (Recommended)". Choices run from "1 FPS (Slideshow)" up to "50 FPS (Max Speed)"; the per-frame delay written into the APNG is exactly 1/fps.
3. Choose Combine? and Image resolution (Optional): "Combine?" is preselected to "Single animation" (all uploads become frames of one APNG); pick "Individual files" to get a separate APNG per photo. "Image resolution" stays on "Keep original" unless you set a Preset Resolution, a percentage, or an explicit Width x Height.
4. Convert and Download: Click "Convert" and save your 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.

Frequently Asked Questions

What exactly is an ERF file, and which cameras wrote it?

ERF stands for Epson RAW Format. It was written only by the Epson R-D1 — announced in March 2004 and described by Wikipedia as the first digital rangefinder ever commercially produced — and by its two successors, the R-D1s (March 2006) and the Japan-only R-D1x / R-D1xG (April 2009). All three pair a 6.1-megapixel Sony ICX413AQ APS-C CCD with a Leica M lens mount. Epson then left the camera business, so ERF is a closed set: no current camera produces one.

Is ERF a compressed raw format?

No. Several converter sites describe ERF as compressed, but the open-source decoders that actually read the format disagree: darktable's RawSpeed handles ERF with its uncompressed decompressor, reading 12-bit samples MSB-first with a control byte inserted roughly every ten pixels. That is why the files are chunky for a 6-megapixel camera — 6.1 million photosites at 12 bits each is already about 9 MB of pixel data by simple arithmetic, before metadata and the embedded preview.

How do I combine several ERF photos into one animated APNG?

Upload every frame you want before converting and leave "Combine?" on "Single animation". Each raw file is rendered to an RGB frame and the frames are assembled in upload order with an infinite loop. Frames of differing sizes are normalised onto a common canvas first, because the APNG assembler cannot resize on the fly — so a sequence shot on one body at one setting gives the cleanest result.

What happens if I upload only one ERF?

You get an ordinary static PNG. With a single rendered frame there is no animation to write, so the file is produced without the acTL, fcTL and fdAT chunks and displays as a still image everywhere. If a plain still is all you want, ERF to PNG is the more direct route and produces a smaller file.

Why choose APNG over GIF for photos from an R-D1?

Because of the palette. GIF stores at most 256 colours per frame, which visibly posterizes skies, skin tones and any smooth gradient in a photographic frame. APNG stores up to 24-bit truecolour and compresses it losslessly, so the rendered frames keep their tonal transitions. The cost is size: a truecolour photographic loop is normally heavier than the same loop crushed to a palette. If size matters more than fidelity, ERF to GIF is the alternative.

Will the APNG be lossless compared with the rendered frames?

The APNG encoding is lossless — PNG uses DEFLATE, and our pipeline additionally runs a Zopfli-based optimizer over the finished file, which shrinks it without touching a pixel. The lossy, one-way step happens earlier: demosaicing the 12-bit Bayer data into 8-bit RGB bakes in a white-balance, exposure and tone interpretation. Keep the original .erf if you might want to re-develop it later.

Does APNG's alpha channel do anything for an ERF source?

Not really. An R-D1 frame is an opaque photograph with no transparent regions, so the alpha channel simply stays fully opaque. APNG's alpha matters when you are animating logos, icons or cut-outs; for camera frames the useful part of APNG is the 24-bit colour, not the transparency.

What happens to my uploaded ERF files after the conversion?

They are uploaded over an encrypted connection, rendered and assembled on our servers, and deleted automatically after a few hours — no sign-up, no watermark, never shared or made public. The practical limit is upload size and time: ERF files are large for their pixel count because the sensor data is stored uncompressed. If you want a shareable still instead of an animation, ERF to JPG is the usual choice, and the ERF converter hub lists every other output we support.