JPG to RAW Converter
Convert JPG to RAW in your browser. You download a Linear DNG (.dng), not a .raw: only a camera can create a genuine RAW, and every editor that opens RAW also opens DNG. Nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
JPG expected · other image formats also work
How to use JPG to RAW
- 1
Add your JPG files: drop them here, choose them, or paste from the clipboard.
- 2
There is nothing to tune: the DNG is written uncompressed. Resizing and rotating are under More options if you need them.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .dng files one at a time or together as a ZIP.
Why use Aback Images for jpg to raw
Where a RAW would go
RAW files are opened by Lightroom, Photoshop Camera Raw, Capture One, darktable, RawTherapee and dcraw-based tools, and every one of them opens the DNG too.
DNG next to JPG
The DNG is written uncompressed, so expect it to be several times larger than the JPG, which stores lossy DCT coding in 8×8 pixel blocks, with colour usually stored at half resolution.
No new artefacts
JPG is already lossy, since it stores lossy DCT coding in 8×8 pixel blocks, with colour usually stored at half resolution; the DNG keeps the decoded pixels uncompressed, so this step adds no compression damage of its own.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
JPG vs RAW
What changes from JPG to RAW
Encoding: the JPG uses lossy DCT coding in 8×8 pixel blocks, with colour usually stored at half resolution; RAW uses uncompressed, lossless JPEG or vendor-specific coding of the sensor data, depending on the maker, and the download is a Linear DNG: demosaiced 8-bit RGB with the colour matrices raw editors need.
Bit depth: 8 bits per channel in the JPG; RAW allows 12 to 16 bits per channel, and the DNG written here has 8 bits per channel, linearised.
Colour: YCbCr shown as RGB, greyscale, or CMYK from print software in the JPG; RAW supports camera-native RGB from a colour filter mosaic, written here as 8-bit sRGB.
Metadata: the JPG can carry EXIF (camera, date, GPS), XMP, IPTC and an ICC profile in APP segments; RAW can carry EXIF and vendor maker notes, almost always with an embedded JPEG preview, but nothing is copied across.
About JPG
JPEG is the universal photo format. It compresses by discarding fine detail the eye is least sensitive to, which makes photos small but blurs sharp edges and text if pushed too far.
A JPEG starts with the bytes FF D8 and is a run of marker segments: APP1 carries EXIF and often a thumbnail, APP2 an ICC profile, DQT the quantization tables that decide the quality, and SOS the compressed scan, which ends at FF D9.
JPG files usually come from cameras, phones, scanners and almost every app that saves photos.
About RAW
Camera RAW files (CR2, CR3, NEF, ARW, DNG, ORF, RW2, RAF and others) hold the unprocessed sensor data from a camera along with an embedded full-size JPEG preview rendered by the camera.
.RAW is an extension rather than one format. Panasonic and Leica compacts wrote TIFF-like .RAW files before Panasonic moved to RW2, and scanners and scientific cameras use .raw for headerless dumps with no width, height or layout recorded, which nothing can read without being told those values.
RAW files come from older Panasonic and Leica compacts that saved .RAW, and scanners or scientific cameras that use the extension for pixel dumps.
When converting JPG to RAW makes sense
Forms and workflows that ask for RAW usually feed a raw editor, and each of those opens DNG as well, so the DNG can take the RAW's place. Keep the JPG if you only need to view or share the picture.
What RAW offers when it comes straight from the camera: Maximum editing latitude in RAW editors; Includes a camera-rendered preview. Its drawbacks: Huge files; Every brand uses its own format; Phones, browsers and websites cannot display it.
Limitations
- JPEG artefacts already in the file, such as blocking near edges and smeared colour, are kept as pixels: a lossless target preserves them faithfully rather than removing them.
- The DNG holds the decoded 8-bit pixels, so it adds no dynamic range or detail beyond the JPG.
More conversions
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Frequently asked questions
Why do I get a .dng file instead of a .raw?
A real RAW is written by a camera and holds the sensor's own readings (12 to 16 bits per channel, stored as uncompressed, lossless JPEG or vendor-specific coding of the sensor data, depending on the maker) along with EXIF and vendor maker notes, almost always with an embedded JPEG preview. A JPG holds no sensor data, so no software outside the camera can create a genuine RAW. The Linear DNG you get instead is Adobe's open raw format, and every editor that opens RAW files opens it with the same raw controls. It holds decoded pixels, so it adds no quality or dynamic range.
Does converting JPG to RAW lose quality?
DNG is written uncompressed, so the pixels are stored exactly as decoded. Artefacts already in the JPG stay, but nothing new is lost.
Are my images uploaded anywhere?
No. Processing happens inside your browser with WebAssembly and Web Workers. The site only downloads the app code and codecs; your files never leave your device. You can confirm this with the live upload counter on the tool, or in your browser's network panel.
Can I process many files at once?
Yes. Drop a whole selection or folder. Files are processed in parallel on several worker threads, each result can be downloaded on its own, and everything can be saved as one ZIP.
Is it free? Is there a file limit or watermark?
It is free with no account, no watermark and no daily limit. The only limit is your device's memory: very large images (over roughly 100 megapixels) may be refused to keep the tab from crashing.