Invert only the bright parts of a photo for the classic darkroom Sabattier look. Set the cut-off, choose brightness or per-channel flipping, and blend the effect in.
Recreates the Sabattier effect, which photographers got by briefly exposing a print to light halfway through developing: the tones above a certain brightness reverse while the darker tones stay put. Here the threshold is a number from 0 to 255. In By brightness mode a pixel is inverted as a whole when its perceived brightness passes the threshold, so colours stay believable. In Per channel mode each of red, green and blue is tested and flipped separately, producing the wilder colour shifts people associate with the effect.
A 3000 × 2000 black and white portrait with a bright white background. At threshold 128, By brightness, 100 percent, the background turns black, the highlights on the face go dark grey and the mid-tones and shadows stay as they were, giving the classic Man Ray look with a glowing edge around the hair. Raising the threshold to 200 keeps the face normal and only reverses the paper-white background, a neat way to get a dark backdrop without cutting anything out. The same settings in Per channel mode on a colour photo turn a blue sky into a warm yellow-orange while grass stays green.
Solarize is for expressive, experimental images: album art, fashion editorials, posters, anything where a surreal metallic look is the point. It is at its best on high-contrast photos with clear highlights. It is not a correction tool and it is not subtle at 100 percent; for a full negative use Invert Image Colors, for flat graphic tones use Posterize Effect, and for a pure black and white cut-out use Threshold.
Threshold is the brightness at which inversion starts; 128 is the middle and gives the strongest effect, 180 and above only touches highlights. By brightness versus Per channel is the difference between a photographic and a psychedelic result. Amount mixes the flipped image back into the original; anything under 100 softens the harsh transition at the threshold. Output Same keeps the original format; PNG preserves transparency if there is any.
What is the difference between solarize and invert? Invert flips every pixel. Solarize flips only the pixels brighter than the threshold, so shadows stay as they were and highlights turn dark. At threshold 0 the two are identical; at 255 nothing changes.
Why do the colours go strange in Per channel mode? Each of red, green and blue is tested against the threshold on its own, so a pixel can have its red flipped but not its blue. That is where the metallic, psychedelic colour shifts come from. Use By brightness for a cleaner, more photographic result.
How do I get a subtle darkroom look rather than a full flip? Set the threshold high, around 190, so only the brightest highlights invert, and bring Amount down to 60 to 80 percent. Skies and specular reflections go dark and silvery while the rest of the photo stays normal.
Is my picture uploaded? No. The threshold test and inversion run pixel by pixel in your browser; the file never leaves your computer.
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