Detail: sharpening, noise reduction and film grain
Press ⌃3 for Detail. Its three sections are the ones to judge up close rather than with the frame fitted to the window: a sharpening radius or a noise threshold cannot be seen at the whole-frame size. Hold ⌘ and scroll over the part of the frame that matters, or pinch, and the photograph grows about the pointer. The canvas covers it.
The 100% rung on the top panel is not a pixel-for-pixel view. The canvas draws a preview of the photograph no more than 2048 pixels along its long edge, and 100% only scales that preview to fill the canvas, so it is larger than the whole-frame size by as much as the frame's shape leaves spare room (a little on a landscape frame, a good deal on an upright one) and not a closer look at the file. The Sharpening section's guide, quoted below, says sharpening is judged at 100%; zoom with ⌘-scroll or a pinch instead, up to eight times the size the rung drew, and read what you see as an enlarged preview.
Sharpening's Radius, and the blur behind Noise reduction's Colour, are counted in pixels of the picture being drawn. An export is drawn at its own size, not the preview's, so the same setting does not look exactly the same there as it does on the canvas.
Sharpening and noise reduction run after every other adjustment on the frame's tonal shape, so both see the photograph almost exactly as it will be delivered. Film grain runs later still, after both of them.
Sharpening
The Sharpening section opens first on this tab.
| Slider | Range | Starts at |
|---|---|---|
| Amount | 0 to 150 | 0 |
| Radius | 0.5 to 3.0 | 1.0 |
| Detail | 0 to 100 | 25 |
Amount is the switch: at 0, Radius and Detail have nothing to shape, so both are drawn dimmed until Amount moves. Radius is how wide an edge the sharpening reaches across. Detail biases it toward fine texture as it rises, rather than toward broad edges.
The section's ? guide puts it in one line: Acutance at the edges: how much, over how wide a radius, on how fine a detail. Judged at 100%, never fitted. Read its last words with the caution at the top of this page in mind.
The section has an eye, and its reset leaves Noise reduction exactly where it was.
Noise reduction
| Slider | Range | Starts at |
|---|---|---|
| Luminance | 0 to 100 | 0 |
| Colour | 0 to 100 | 0 |
The two are genuinely separate tools. Colour softens the frame's colour alone, which is where the speckle of wrong hues lives in a high-ISO frame, and it is close to invisible on the frame's detail. Luminance takes the frame's brightness apart into five scales of detail, from single pixels up to blocks, removes what looks like noise at each, and puts the picture back together. It reduces steadily from about 10 upwards and never makes a frame noisier.
The section's ? guide puts the difference in two sentences: Luminance noise is the grain in flat tone; colour noise is the speckle of wrong hues. Both cost detail, which is why they are two sliders. Move each only as far as the frame needs; Luminance gives up more fine texture the higher it goes.
The section has an eye, and its reset leaves Sharpening where it was.
Film grain
| Slider | Range | Starts at |
|---|---|---|
| Amount | 0 to 100 | 0 |
| Size | 0 to 100 | 25 |
| Roughness | 0 to 100 | 50 |
Amount is the switch; Size and Roughness are dimmed until it moves. Size is the grain's physical scale, set as a fraction of the photograph's long side rather than a fixed pixel count, so the same setting looks like the same grain on the preview and on a full-size export. Roughness is the grain's own contrast — smooth and flat at 0, harsh at 100 — not its size.
The grain is colourless, an equal texture on all three channels, the way real film's density fluctuations look. Rendering the same frame twice with the same settings gives the same grain every time. The note under the section says why it sits here: Grain is added last, after sharpening and noise reduction, so it survives the render. Where a creative vignette is on the frame too, the grain is added first and the vignette darkens the corners with their grain, the way a lens would have photographed already-grainy film.
The section has an eye, and its reset leaves the vignette on the Lens tab untouched.