Identify a film scan with or without its border
Negative Converter suggests a film type when you import a new photo. It can use image-wide orange-mask evidence even if you did not photograph the film edge. The result is a suggestion: some positive and negative images cannot be distinguished from pixels alone.
What evidence does detection use?
| Scan evidence | Likely interpretation | Limitation |
|---|---|---|
| A consistent orange mask across the image | Color negative | A very warm positive scene can look similar. |
| A uniform orange rebate brighter than the image | Stronger color-negative evidence | The photographed edge must actually be film rebate. |
| A clear neutral rebate around a grayscale image | B&W negative suggestion | A white border on a positive image can resemble it. |
| Consistent readable DX film information | Film type from the film database | Unreadable or contradictory markings are not automatically trusted. |
| No mask and varied colors | Positive suggestion | A previously color-balanced negative may have no orange mask. |
What if my scan has no film edge?
You do not have to recapture the border. Detection inspects the whole image and supports cropped orange-mask negatives. After choosing Color negative, use the No Border / ES-2 mask workflow, automatic film-base estimation, or a reference from the same roll if available.
For an already color-corrected scan, inspect the preview and set the type yourself. File extensions and camera model names do not establish positive or negative polarity: a RAW file can contain either kind of photograph.
Why is a borderless black-and-white scan uncertain?
Both a B&W negative and its positive inversion contain only gray values. Without additional evidence, the image does not provide a unique answer. The app therefore keeps the positive orientation and prompts you to select B&W negative or Positive in Conversion.
This avoids pretending a contrast or brightness heuristic is a reliable identification. There is no published accuracy percentage for a representative real-film dataset.
Correct a suggestion and keep the decision
- Open Conversion and inspect the confidence message and preview.
- Select Color, B&W or Positive explicitly if the suggestion is wrong.
- For positives, choose Correct slide or Edit only.
- Continue editing. Saved settings preserve that photo’s manual type when you switch away and return.
For a known uniform batch, disable Detect film type on import and choose the type to apply to new photos. With automatic detection enabled, never-viewed batch exports are assessed individually instead of inheriting the preceding photo’s type.
Related workflow guides
Read the orange-mask guide, positive slide correction guide and batch export guide. Implementation and tests are public in the source repository.
Questions and answers
Must I photograph the film border for automatic detection?
No. The detector also uses the image area, including broad orange-mask evidence. A visible rebate or readable DX code can provide stronger evidence but is not required.
Can every B&W scan be identified automatically?
No. A borderless grayscale positive and negative can both fit the same pixel evidence. The app prompts you to choose the polarity instead of claiming certainty.
Does a RAW file mean the photo is a negative?
No. RAW describes the file encoding, not the subject. A camera RAW file can contain a negative scan, a positive slide or an ordinary digital photograph.
Will the app overwrite my manual film-type choice?
Saved per-photo settings retain the selected type. Automatic detection applies to new photos and never-viewed batch items.