Negative Conversion
Density-space algorithms that bring out true film color
Cast removal is more than simple inversion. NegRGB converts negatives in density space: max density, density contrast and density center map to the optical behavior of film, with per-channel RGB exposure and gamma correction on top — auto-computed or hand-tuned, the result is a clean, transparent base.
Highlights
- —Max density, density contrast and density center for precise conversion
- —Per-channel RGB exposure and contrast (gamma) to fix any color cast
- —Auto tone / auto white balance / auto shadow correction in one click
- —Auto black point: drives the darkest film base to pure black, referenced from the auto-crop base ring (negatives only)
- —Region-pick statistics: expose for your subject, not the whole frame
- —Paper simulation: Kodak papers, cine print 2383/2393, Ilford B&W papers
- —Sprocket preservation keeps scanned sprockets white, not black
- —Batch auto-adjust unifies exposure and white balance across a whole roll
Density space, not brute-force curves
Film density relates to light logarithmically, so NegRGB converts in density space: max density sets the white point and overall brightness, density contrast shapes global contrast, and density center is the pivot that contrast rotates around. Three parameters with distinct jobs that never fight each other — set brightness, add depth, then trim brightness again; two or three iterations usually suffice. Channel purity and channel hue fine-tune per-channel color, and a monochrome switch is one click away.
Auto is just the starting point
New photos get automatic exposure and white balance on import, producing a usable baseline. Auto tone also computes an auto black point at the same time — using the film-base ring found by auto crop as the reference, it drives the darkest part of the base to pure black — and the Tone, Channel Exposure and Channel Contrast Auto buttons all base their statistics on the cropped frame. For more precision, activate region picking on a panel and click or drag a reference area in the preview — the Tone, Channel Exposure and Channel Contrast panels can each recompute their auto values from that region alone: expose off the sky, white-balance off a gray card, set contrast from the shadows. You choose the reference.
- —Clicked points expand to a minimum 2% sampling area for robust results
- —Every pick creates its own undo record — revert anytime
Unify a whole roll in one pass
Lighting is usually consistent across a roll. Select multiple photos and run batch auto-adjust: NegRGB tiles the thumbnails into one large image, runs two rounds of auto exposure and white balance, and applies the shared parameters to every selected photo. The roll evens out in one pass, ready for per-photo refinement — with an undo record saved automatically beforehand.