Reproduce a flatbed scan
A scan is not a copy. The lamp, the sensor bar, the glass, and the lid each leave a mark, and together they are why a scanned print looks unmistakably different from a photograph of the same print.
Six of those marks are reproduced here, and each has its own control.
Tonal flattening
The largest single difference. A scanner lamp sits at one brightness and the sensor has less range than the print in front of it, so shadows never reach black and highlights never reach white. At the default the black point lands near 18 and the white point near 241.
This is the control that decides whether an image reads as scanned at all. Everything else is texture on top.
Lamp cast and platen softness
Cold cathode lamps in older flatbeds run warm; LED bars in newer ones run slightly cool. Lamp cast pushes red up and blue down, or the reverse at negative values.
Platen softness is the glass and the optical path. It is a small blur, capped at about 0.5% of the shorter side, which takes the edge off fine detail without turning the image into a smear. Text scans lose their crispness this way long before they lose legibility.
Glass dust and line banding
Dust specks are placed on a coarse grid sized against the image rather than against the pixel count, so they stay the same physical size whether the preview is 1200px wide or the export is 6000px. Roughly a third come out light and the rest dark, which is what a mix of dust on the glass and dirt on the print looks like.
Line banding is vertical. A scanner reads one row at a time across a fixed sensor bar, so any variation between sensor elements repeats down every column of the result. Camera noise has no such structure, which is why banding sells the effect.
Skew and the paper edge
Nobody lines a print up perfectly on the glass. The skew rotates the image by up to 6° in either direction and expands the canvas to fit, filling the exposed corners with the platen colour.
A shadow is drawn along the paper edge, because the lid never sits flat against a print and the gap catches the lamp. Platen margin controls how much paper shows around the image.
Example: a photo for a scrapbook page
Try 70% tonal flattening, 18% lamp cast, 30% platen softness, 10% sensor noise, 35% glass dust, 25% line banding, 2.4° skew, 9% margin.
If it reads as a filter rather than a scan, the usual cause is too little flattening and too much dust. Raise flattening, drop dust below 25%, and keep the banding subtle.
Export
Output keeps the source format unless the canvas needs transparency, which this effect never introduces: the platen fill covers every exposed corner. Because the skew and margin are computed from percentages, the preview and the full-resolution download frame the paper identically.