DngToTiff: DNG to 16-bit TIFF without interpolation

← Overview

For mono-converted fp / fp L bodies (including full-spectrum and IR conversions): their raw values are the image, so normal raw converters’ debayering only adds artefacts. DngToTiff writes the sensor data as 16-bit greyscale TIFFs. It decodes the DNG bit-for-bit like LibRaw and does no colour interpolation.

Quick use

Drag DNG files, or a folder, onto DngToTiff.exe (or a shortcut to it). TIFFs are written next to the DNGs. The window stays open to show the result.

Command line

DngToTiff.exe <files-or-folders> [options]

| Option | Effect | |—|—| | (none) | display-ready: black level subtracted, the camera’s BaselineExposure applied (fp +1.0 EV, fp L about +0.94 EV), sRGB tone curve, cropped to the DNG DefaultCrop | | --ev <stops> | extra exposure, e.g. 1, -0.5 | | --flat <file.dng> | flat-field correction (see below) | | --linear | linear light 0-65535, for astro or scientific processing (looks very dark on screen) | | --raw | untouched sensor values (black level kept, 14-bit range) | | --full | keep the full sensor area (no crop) | | --out <folder> | write the TIFFs to another folder | | --recurse | include subfolders |

Examples:

DngToTiff.exe D:\Photos\Trip
DngToTiff.exe D:\Photos\Trip --ev 1 --out D:\Photos\Trip\tiff
DngToTiff.exe D:\Photos --recurse --linear --full --out D:\linear

Flat-field correction (--flat)

Removes vignetting, the IR “hot spot” and dust spots in one step, the same way astro flats work.

  1. Shoot a flat: an evenly lit grey card or white wall, slightly out of focus, with the same camera, lens, aperture and filter, exposed to about mid-grey.
  2. Convert with it: 
    DngToTiff.exe D:\Photos\Trip --flat D:\Photos\Trip\greycard.DNG --out D:\Photos\Trip\tiff

    The flat is black-subtracted, lightly smoothed (keeping dust spots), normalised to the image centre, and divided out of each frame’s linear data before exposure and tone curve are applied. This is more accurate than inverting and blending in an editor. The program prints the flat’s corner fall-off and gain range.

The output is deliberately flat (no contrast curve, like any raw file): add contrast in your editor.