JPG to RAW

Key takeaways

• RAW and JPG hold different things: a RAW file keeps the values the sensor measured; a JPG keeps a rendered 8-bit picture. In our test the RAW files took 0.6 to 2.3 bytes per sensor pixel and their JPEG previews 0.05 to 0.73.
• Going the other way works: 52 of 79 of the RAW files we tested contained a JPEG, and this tool takes it out in 37 to 122 ms.
• A JPG saved with a .raw or .dng name is still a JPG. Wikipedia describes DNG conversion as extracting the raw image data from a source file and assembling it; a JPG has no raw data to extract.
• If you need more editing room from a JPG, the useful steps are to edit it once, export at high quality, and keep the original; nothing makes up for lost sensor data.
• Wikipedia notes a raw file is typically 2 to 6 times larger than a JPEG; in our files the preview was 0.1% to 19.1% of the RAW size.

Measured: bytes per pixel, RAW against JPEG

Real RAW files in our test took 0.6 to 2.3 bytes per sensor pixel; their JPEG previews took 0.05 to 0.73. If you have the RAW file, this page's tool takes the JPEG out of it.

Measured with the tool's own code (the same functions the page runs) on 79 camera RAW files from the CC0 sample collection at raw.pixls.us: 27 file types from 28 makers, from compact cameras to medium format. Every JPEG the tool extracted was then read by ffprobe and decoded end to end by ffmpeg; the size, quality and sensor figures come from the files themselves.

A rendered picture and a RAW file are different amounts of information. The RAW file stores a number for every sensor pixel, with 12 to 14 bits per value; the JPEG stores a compressed 8-bit picture, which is why it is so much smaller.

What you can do instead

• If you still have the RAW file, extract its JPEG with the tool above or develop it in a RAW editor.
• If you only have the JPG, edit it once at the best quality available and keep the original.
• If a service asks for RAW, it needs the camera file; a renamed JPG will be rejected or treated as a JPG.
• If you want a DNG, convert from the camera RAW with a RAW converter; Wikipedia describes conversion as extracting the raw image data from the source file and assembling it in the DNG layout.

What you get: the camera's picture, not your RAW data

The preview is what the camera rendered at the moment of shooting: its white balance, its picture style, its sharpening, in 8 bits per channel. Wikipedia notes that processing from the sensor to a viewable image involves operations such as demosaicing, color translation and compression, and that a RAW developer lets you change them afterward; the preview has them baked in.

That makes it a good proof and a good file to share quickly, and a poor starting point for rescuing a dark or blown-out frame. If you need that, develop the RAW file in a RAW editor.

Related tools

Free tools:RAW to JPGHEIC to JPGCompress an image

How the preview is found

Most RAW formats are built on the TIFF layout, and others (Canon CR3, Fujifilm RAF, Sigma X3F) have their own. Rather than rely on each maker's tags, the tool walks the file looking for the start of a JPEG and then reads that JPEG segment by segment until its end marker, so a stray byte pair inside compressed data is not mistaken for an image. It keeps baseline and progressive JPEGs and skips the lossless JPEG streams that hold the sensor data themselves.

It then picks the largest picture, lists the others, and saves it unchanged. Scanning took 37 to 122 ms in a browser for files of 43 MB to 64 MB.

How the numbers were measured

The tool's own scanning code ran on 79 CC0 files; the script, the list of files and the full results are saved with the page's evidence. For each file we recorded every JPEG found, the one used, its estimated quality (from the luminance quantization table, compared with the standard table), and the sensor image size where the file states it. Each extracted JPEG was read by ffprobe and decoded by ffmpeg to the end: 52 of 52 passed.

Questions people ask

Related

Sources and how we checked

1. Wikipedia: Raw image format (read 2026-10-10)
2. Wikipedia: Digital Negative (DNG) (read 2026-10-10)
3. raw.pixls.us: RAW sample database (CC0) (read 2026-10-10)
4. FFmpeg Documentation: ffprobe (used to check every extracted JPEG) (read 2026-10-10)

Reviewed October 10, 2026. The measurements ran the tool's own code on 79 camera RAW files from the CC0 collection at raw.pixls.us and decoded every extracted JPEG with ffmpeg. The files and results are in data/seo/hub/evidence/2026-10-10/raw.