Correct slide film without inverting it
Negative Converter corrects positive slide scans on your device. Choose Positive, then Correct slide for automatic tone and reliable neutral balance, or Edit only to keep the original rendering and make manual adjustments.
Which positive mode should I use?
| Mode | What it does | Use it for |
|---|---|---|
| Correct slide | Analyzes the image, lifts compressed tones with a bounded highlight shoulder, and balances reliable neutrals. | Camera scans of reversal film that need tonal correction. |
| Edit only | Skips automatic tone and white-balance analysis. Existing manual edits still apply. | Finished scans, digital photos and negatives already converted elsewhere. |
Neither mode inverts the image or removes an orange negative mask. At neutral settings, Edit only preserves the decoded 16-bit pixel values through the conversion stage. JPEG export, manual adjustments and image repairs can change those values.
How to correct a slide scan
- Import a JPG, PNG, TIFF or supported camera RAW scan. Check the suggested film type.
- Open Conversion and select Positive. You can make this choice even when the scan has no film border.
- Select Correct slide. Inspect the brightest textured areas and neutral objects before changing exposure, highlights or white balance.
- Use Edit only if the scan already looks right. Apply a deliberate preset or color adjustment only when you want that additional rendering.
- Export PNG or TIFF at 16-bit for further editing, or JPEG for sharing.
Why use a common tone mapping?
Stretching red, green and blue independently can shift the colors of a positive scan. The positive pipeline uses a shared tonal mapping and a neutral default color model. Automatic white balance requires strong neutral evidence; scenes without it retain their existing balance. The highlight shoulder avoids discarding bright values simply because they lie above a histogram percentile.
This protects detail present in the scan. It cannot reconstruct highlights already clipped by the camera, scanner or earlier software. Keep the original RAW or high-bit-depth scan.
Scans with no border
A film border is optional. Import detection can inspect the image itself, while the Positive button always provides an explicit choice. A warm positive scene can resemble the orange mask of a negative, and a grayscale positive can resemble a B&W negative. Treat a suggestion as something to inspect, not a guaranteed identification.
See how automatic film-type detection handles cropped scans.
Source and implementation
The implementation and tests are public in the Negative Converter repository. The workflow is inspired by the distinction between Positive and Edit Only described in Negative Lab Pro’s v3.1 announcement. Negative Converter uses its own processing pipeline; it does not reproduce or claim identical results to that product.
Questions and answers
Do I need to invert slide film?
No. A developed slide is already positive. Use Positive mode to correct it, or Edit only to apply manual adjustments without automatic analysis.
Can I correct slides without photographing the film border?
Yes. Positive processing works on the image area alone. Select Positive manually if automatic film-type detection is uncertain.
Does Edit only change the original scan?
With neutral controls, the conversion stage preserves decoded pixel values. Manual edits, repairs and the selected export format can change the exported image. The source file is retained.
Can this recover blown highlights?
It preserves highlight differences present in the decoded scan. It cannot recover detail that the input file has already clipped.