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What is 29a.ch?
29a.ch is the personal website of Jonas Wagner, a developer who publishes browser-based experiments and tools there. It functions less as a commercial product site and more as a public workshop: small, focused utilities you can run directly in a browser, plus occasional write-ups explaining how they were built and what their limits are.
What you'll find there
The site's main draw is a set of interactive experiments, including:
- TimeStretch Player — an audio player that changes speed and pitch independently.
- Analog Film Emulator — a tool for approximating the look of analog film.
- Forensically — a set of tools for analyzing photos forensically.
- Neonflames — a browser toy for drawing nebulae.
Alongside these, Wagner posts articles. One example covers adding C2PA content-credential support to Forensically, including a candid discussion of what signatures do and don't prove, privacy concerns around remote manifests (which he disabled), and the large file-size cost of the underlying library.
Who it's for
- Curious tinkerers who want to try audio, image or generative-visual tools without installing anything.
- Photographers and journalists who need a quick way to inspect an image's metadata or provenance.
- Developers interested in how such tools are implemented, including the trade-offs involved.
How to approach it
Start with the experiment that matches your task rather than browsing everything: if you have a suspicious image, go straight to Forensically; if you want to slow down a recording without the pitch dropping, use TimeStretch Player. Treat the tools as practical aids, not authorities — Wagner himself notes that a valid signature only tells you who signed something, not whether the content is true, so verify important claims through other channels.
How can I use Forensically to check if a photo has been manipulated?
Forensically is a browser-based set of photo forensics tools by Jonas Wagner. To check whether a photo has been manipulated, open the tool, load the image, and work through the individual analyses rather than expecting a single "manipulated / not manipulated" verdict. Each tool highlights different kinds of traces, and you interpret them together.
Typical workflow
- Load the image into Forensically.
- Run Error Level Analysis (ELA) to look for regions that recompress differently from the rest of the image — often a sign of pasted or retouched areas.
- Use Clone Detection to find duplicated regions, which can reveal copy-stamped or patched content.
- Use Magnifier and Noise Analysis to inspect edges, textures and noise consistency, since edits often leave locally smoother or noisier areas.
- Check Metadata and, where present, C2PA provenance information.
What each signal tells you
| Tool | What it can reveal | Main limitation |
|---|---|---|
| Error Level Analysis | Regions with different compression history | Strong JPEG re-saving or resizing can mask edits; can produce false positives |
| Clone Detection | Duplicated image regions | Legitimate repeated texture (bricks, foliage) triggers it too |
| Noise Analysis | Inconsistent sensor noise | Denoising, heavy compression or low light reduce reliability |
| Magnifier | Jagged edges, mismatched lighting, seams | Requires careful visual judgement |
| Metadata / C2PA | Camera data, editing software, signed provenance | Easily stripped; signatures only as trustworthy as the signing keys |
A concrete example
Suppose a photo of a crowd appears to have an extra person added. ELA might show that person's outline as a brighter or differently-textured patch, Clone Detection might match their clothing against another part of the image, and Noise Analysis might show the added region with smoother noise than the surrounding scene. Any one of these is suggestive; together they make a stronger case.
Important caveats
Jonas Wagner notes in his own writing on C2PA support that digital signatures do not inherently guarantee trustworthiness — you still need to trust everyone with access to the signing keys — and he advises taking displayed signatures "with a big pinch of salt." He also deliberately disabled remote manifests in Forensically to avoid them being used as tracking beacons. Treat every result as an indicator, not proof.
Next step
If you need a conclusion you can rely on, combine Forensically's output with a second opinion: examine the file's metadata with an EXIF viewer, compare against the original if you have it, and consult a qualified forensic examiner for anything with legal or professional consequences. For general background on image provenance, see Content Credentials.
What tools does the Analog Film Emulator offer for creating a retro look?
The Analog Film Emulator is one of the browser-based experiments on 29a.ch, Jonas Wagner's personal site. It is described there simply as "a tool to emulate the look of analog film." The site does not break it down into named controls or presets, so the honest answer is that the visible evidence supports a single-purpose film-look tool rather than a listed toolkit of separate retro features.
H3 What this means in practice
If you want a retro or vintage look for a photo, this is the kind of tool you would use to apply a film-like grade in the browser, without installing desktop software. Typical analog-film emulation aims at a few things:
- Color response: shifting hues and saturation away from a clean digital rendering.
- Contrast and tone: softer highlights, lifted or crushed shadows.
- Grain and texture: adding the unevenness that film scans tend to show.
Those are general characteristics of film emulation as a category, not features the page specifically documents for this tool. Treat them as what to look for, not as a confirmed feature list.
H3 Choosing between this and the site's other tools
The site groups several experiments together, and picking the right one matters more than the tool's internal options.
| Tool | Best for |
|---|---|
| Analog Film Emulator | Applying a film-style aesthetic to an image |
| Forensically | Analyzing a photo's authenticity and metadata |
| TimeStretch Player | Changing audio speed and pitch independently |
| Neonflames | Drawing a nebula in the browser |
If your goal is a retro look, the Analog Film Emulator is the relevant one. If your goal is to check whether an image has been manipulated, Forensically is the match.
H3 A practical next step
Open the tool with one image you already know well, apply the film effect, and compare it side by side with the original. Judge whether the grain and color shift suit your subject — film looks flatter on clean product shots and more natural on portraits and street scenes. Since it runs in the browser, you can test quickly and decide whether it is worth keeping in your workflow before investing more time.
How do I use the TimeStretch Player to change audio speed without affecting pitch?
Open 29a.ch, find the TimeStretch Player under Experiments, load an audio file, then adjust the speed and pitch controls independently — the whole point of the tool is that changing playback speed doesn't have to drag the pitch along with it. Set speed where you want it, then correct pitch (or leave it where you want it) with the separate pitch control rather than expecting one slider to do both.
How to approach it
- Load a track you know well, so you can hear immediately whether the pitch has drifted.
- Change speed first. On a standard player, slowing audio down lowers pitch and speeding it up raises pitch; here you can counteract that.
- Use the pitch control to compensate. If you want the original key preserved, nudge pitch back until the track sounds like the same voice or instrument, just at a different tempo.
- Check the result on material with clear tonal content — a solo vocal or a sustained piano note exposes pitch shifts that drums and noise hide.
When this matters
| Goal | What to adjust |
|---|---|
| Learn a fast passage at a slower tempo, still in the original key | Lower speed, keep pitch fixed |
| Transcribe a solo without it sounding like a different instrument | Slow down, then restore pitch |
| Practise along with a recording in a different key | Leave speed alone, shift pitch |
| Create a deliberate chipmunk or slowed-and-reverbed effect | Move both controls in the same direction |
Practical caveats
Time-stretching is not free of artefacts. At extreme settings — very slow or very fast — you may hear smearing, metallic ringing or choppy transients, especially on dense mixes. Modest changes usually sound cleanest. If you only need a small tempo change, the correction is easier to make sound natural.
Also decide up front whether you want the audio to stay in its original key. That single choice tells you whether to touch the pitch control at all.
What does the C2PA support in Forensically mean for verifying photo authenticity?
C2PA support in Forensically lets you read signed provenance metadata embedded in a photo — who or what claims to have created or edited it, and when — rather than judging authenticity from pixels alone. In practice it adds a provenance check alongside Forensically's existing image-forensics tools (error-level analysis, clone detection, metadata inspection). It is a reading and display feature, not a truth guarantee.
What the signature actually tells you
- The C2PA metadata is signed and optionally timestamped by a timestamp authority.
- Forensically surfaces limited signature details — in Jonas Wagner's own testing, the C2PA JavaScript library exposed little beyond the subject organization, algorithm, issuer, certificate serial number and signing time.
- A valid signature means the manifest has not been altered since signing and that it was signed by the holder of a particular key. It does not mean the content is accurate, unedited before signing, or from a trustworthy publisher.
Wagner's own caveat is worth taking literally: he advises treating the signatures shown in Forensically "with a big pinch of salt," because trust depends on who controls the keys, and it is unclear what is validated before a certificate appears on the known-certificate list.
Practical trade-offs
| Aspect | Benefit | Limitation |
|---|---|---|
| Signed manifest | Detects tampering with provenance data after signing | Trust still rests on the signing key holder |
| Timestamping | Can anchor when signing occurred | Optional; absence weakens the timeline |
| Remote manifests | Keeps asset file size small | Can act as tracking beacons when metadata is viewed |
| Library size | Full standards support | Heavy: roughly 350 kB main module, 165 kB worker, 5.4 MB WebAssembly in Wagner's build |
Wagner disabled remote manifest support in Forensically, both via configuration and a Content Security Policy that blocks the requests, so viewing metadata there will not phone home. That is a deliberate privacy choice, and it means some assets with remote-only manifests will show less information than a viewer that fetches them.
How to use it in a real workflow
Suppose a press officer receives a photo said to be an original from a wire service. Open it in Forensically, check whether a C2PA manifest is present, note the issuer and signing time, then use the other forensic tools to look for cloning or resaving artifacts. Treat the manifest as one corroborating signal: it is strong evidence about the signing event, weak evidence about the scene depicted. If no manifest appears, that is not proof of manipulation — most images in circulation have none.
For background on the standard and its verification service, see Content Credentials and C2PA.
How can I draw my own nebula with Neonflames?
Open 29a.ch in a modern desktop browser and choose Neonflames from the Experiments list. It is a browser-based drawing toy where you create a nebula by placing and shaping glowing clouds of colour rather than painting with a normal brush. Nothing needs to be installed, and the result is a generated image you can save or use as a wallpaper, background or texture.
A practical way to start
- Work on a dark canvas. Nebulae read best against black, so build up faint layers first and add brighter cores later.
- Block in the overall shape with a few broad, dim clouds. Keep the composition loose at this stage.
- Add colour variation. Real nebulae mix warm and cool tones, so introduce a second or third hue in overlapping areas instead of one flat colour.
- Brighten only the centre or a few knots of gas. Strong highlights in one or two places give the image depth.
- Export or screenshot when the balance looks right, then try a second version with different colours.
What to expect and where it fits
Neonflames is best treated as a quick generative sketchpad. It suits someone who wants a space-themed background in a few minutes without learning image-editing software, and it is also useful for testing colour combinations before committing to a larger illustration. The trade-off is control: you are steering a generative process, so fine detail and exact placement are harder than in a conventional paint program. If you need precise editing afterwards, bring the exported image into a raster editor.
Related tools on the same site
If your interest is space imagery rather than photo analysis, Neonflames is the relevant experiment. The same site also hosts a TimeStretch Player for changing audio speed and pitch independently, an Analog Film Emulator for film-style looks, and Forensically for examining photos. For a broader look at generative and creative coding work, 29a.ch is the place to browse.
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