RAW to JPG

Key takeaways

• 52 of 79 RAW files we tested held a JPEG preview (79 files from 76 camera models).
• The preview is 0.02 MP to 50.3 MP: Olympus C7070WZ gave 0.02 MP, Canon EOS 5DS gave 50.3 MP. 19 of the 34 with a known sensor size have at least 90% of the sensor's pixels.
• Small: the preview was 0.1% to 19.1% of the RAW file's size, so the JPG is far smaller than the file you started with.
• Estimated JPEG quality of the previews: 32 to 99 on the 1 to 100 scale. Cameras use their own tables, so this is an equivalent, not a setting you can change.
• It is quick: finding the preview took 10 to 117 ms per file in our run, and 37 to 122 ms in a browser for the largest files (43 MB to 64 MB).
• It is the camera's own rendering (white balance, style and sharpening already applied), not your RAW data; you cannot recover shadows or highlights from it.

Measured: which RAW types hold a preview

In our test of 79 files from 27 RAW types, 52 of 79 contained a usable JPEG. Of the 34 where the file also states the sensor size, 19 held a preview with at least 90% of the sensor's pixels; the rest held smaller previews, down to 0.02 MP.

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.

Wikipedia's article on raw files says most of them contain a full size JPEG conversion used to preview the file on the camera's LCD panel. Of our 79 files, 52 held a usable JPEG (66%). Of those where the file states the sensor size, 19 of 34 were within 90% of the sensor's pixels. The claim is true for many modern bodies, and false for plenty of others.

Measured: preview size against the sensor

19 of 34 previews had at least 90% of the sensor's pixels. Previews below 1 MP are fine on a phone and poor on paper; 7 of the 34 were that small.

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.

Rotation

Phones and cameras record which way they were held in the RAW file, and some previews do not carry that flag. In our samples the tool copied a rotation flag from the RAW container into the JPEG for 1 file so the picture shows upright.

When there is no preview

27 of our 79 files held no JPEG the tool could use: DCR, DNG, 3FR, IIQ, GPR, CRW, ERF, RAW, FFF, MRW, MEF among them. The tool says so instead of guessing. In those files the only picture is the sensor data, and a RAW developer is needed.

The tool saves the largest valid JPEG in the file and lists the others. In a few old compact-camera files that is only a thumbnail, and the table on this page shows its size so you can see when that happens.

Free tools:HEIC to JPGCompress an imageRemove EXIF data

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. raw.pixls.us: RAW sample database (CC0) (read 2026-10-10)
3. 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.