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A RAW file is the unprocessed data straight off the camera sensor, before any white balance, sharpening or compression is baked in — and that is exactly why archives favour it. Processing RAW for archives means turning that sensor data into a faithful, colour-accurate, 16-bit TIFF master using a calibrated profile rather than the camera's automatic guesses. This beginner's guide walks through the core ideas in plain language and a small worked example you can follow start to finish.
What is a RAW file, in plain terms?
Think of a JPEG as a meal the camera has already cooked and seasoned: the white balance, contrast and sharpening are decided for you and cannot be fully undone. A RAW file is the raw ingredients. Nothing is decided yet, the full tonal range the sensor captured is intact, and you make the cooking decisions later — when you have a colour target, a calibrated screen and an archival standard to meet. That flexibility is the whole point for preservation: you can re-process the same RAW years from now to a better standard.
Why does archival work prefer RAW?
Three reasons matter to an archivist:
- Maximum information — typically 12-14 bits per channel of tonal data, far more than an 8-bit JPEG, so highlights and shadows survive.
- No irreversible decisions — white balance and tone are applied non-destructively and can be redone.
- Objective colour — you can build a camera profile from a shot colour target instead of trusting the camera's auto white balance.
The trade-off is that RAW formats (.cr3, .nef, .arw) are proprietary, so you do not keep them alone as your only master.
RAW or TIFF — which is the master?
The processed, calibrated 16-bit TIFF is the preservation master because it is an open, stable format that any future tool can read. Many institutions also retain the original RAW as a source file, but relying on RAW alone is risky: it is proprietary and tied to vendor decoders that may not exist in 30 years. A common policy looks like this:
| File | Role | Keep long-term? |
|---|---|---|
Camera RAW (.cr3) | Source/source-of-truth | Optionally retained |
| Processed 16-bit TIFF | Preservation master | Yes — the archival copy |
| JPEG/derivative | Access copy | Regenerable, not preserved |
A small worked example with darktable
Here is the whole pipeline using the free, open-source darktable. The idea: open the RAW, set neutral white balance from the target, apply a camera profile, and export a flat 16-bit TIFF.
bash
# 1. Shoot your batch with a colour target as the first frame, same light.
# 2. In darktable, open the target frame and pick the neutral grey patch
# with the white-balance "spot" tool to set objective white balance.
# 3. Copy that white-balance setting to the rest of the batch.
# Headless batch export to 16-bit TIFF using darktable-cli:
for raw in raw/*.cr3; do
base=$(basename "$raw" .cr3)
darktable-cli "$raw" "sidecar.xmp" "masters/${base}.tif" \
--core --conf plugins/imageio/format/tiff/bpp=16
doneThe sidecar.xmp carries your white-balance and profile decisions so every file in the batch is processed identically and non-destructively — the RAW is never altered.
What settings should I actually use?
Keep the master honest and minimal:
- White balance: set from the target's neutral patch, not "auto".
- Bit depth/format: 16-bit uncompressed TIFF.
- Colour space: a known wide profile (Adobe RGB or wider), embedded as an ICC profile.
- Sharpening/contrast: none, or near-none, on the master.
The preservation master should look slightly flat and neutral — that is correct. Punch and clarity belong in access derivatives, not in the archival record.
When do I add sharpening and contrast?
Only when making access copies. Generate a derivative from the master, then apply sharpening, a contrast curve and resizing for the web or a viewer. Because the master stays neutral, you can regenerate derivatives to new tastes or platforms forever without ever degrading the archival original. This separation — neutral master, enhanced derivative — is the single habit that distinguishes archival RAW processing from ordinary photo editing.
Key Takeaways
- RAW holds unprocessed sensor data with no baked-in white balance or compression.
- Use RAW for the extra tonal data and the freedom to re-process to future standards.
- Keep the calibrated 16-bit TIFF as the preservation master; retain RAW only as a source.
- Set white balance objectively from a shot colour target, not auto.
- darktable and RawTherapee process RAW non-destructively and batch-export to TIFF.
- Keep masters neutral and flat; apply sharpening and contrast only to access derivatives.
Frequently Asked Questions
What is a RAW file and why use it for archives?
A RAW file holds the unprocessed sensor data straight from the camera, with no baked-in white balance, sharpening or compression, which gives you the maximum information and the freedom to re-process later as standards change.
Do I keep the RAW file or the processed TIFF as the master?
Most institutions treat the processed, calibrated TIFF as the preservation master and may also retain the RAW as a source file; the RAW alone is risky because formats are proprietary and tools change.
What free software processes RAW for archival work?
darktable and RawTherapee are the leading open-source RAW processors; both support colour-target profiling, non-destructive editing and batch export to 16-bit TIFF.
Should I shoot a colour target with every RAW batch?
Yes. A target shot under the same lighting lets you build a camera profile and set neutral white balance objectively, which is what makes archival colour reproducible rather than a matter of taste.
What bit depth and format should I export to?
Export to 16-bit uncompressed TIFF in a known colour space such as Adobe RGB or a wide gamut profile, so you preserve tonal range and avoid the banding that 8-bit and lossy formats introduce.
Is it OK to apply sharpening and contrast to archival images?
Keep the preservation master neutral with minimal adjustment; apply sharpening, contrast and other enhancements only to access derivatives, so the master remains a faithful record.