Download RawTherapee 4.0.12 User Manual

Raw Tab
Demosaicing
Method
To display a raw file - any raw file made by any camera - its data has to be
'demosaiced'. That's why opening a raw file always takes a bit longer than
opening a JPEG or TIFF file, where the data is already 'display-ready'.
RawTherapee offers several demosaic algorithms, each with its own
characteristics. The differences between them are often very subtle - one
might need to zoom in to 200-400% to discern them - but since the program
works on a pixel-by-pixel basis and demosaicing is the basis upon which all
other tools work, the choice of demosaicing algorithm can have a visually
significant effect when combined with other tools, such as the sharpening
ones. The choice of a certain algorithm influences among other things the
quality of very fine details in the image, whether false maze patterns will
appear, and decides how well colored edges are rendered.
RawTherapee uses the Fast algorithm to initially open the image for editing.
After this the selected demosaic method is applied when the image is zoomed
to 100% magnification or when the detail window is opened. The selected
method is also used for batch processing. It is not recommended to select the
Fast method for the final conversion, as it is a low-quality algorithm for display
purposes.
AMaZE (Aliasing Minimization and Zipper Elimination) is the default demosaic
method of RawTherapee, as it yields the best results in most cases. VNG-4
used to be (in version 2.4) the preferred algorithm for Olympus cameras, as it
eliminates certain maze pattern artifacts that might be created by the other
methods. Since version 3.0 of RawTherapee, Olympus users might prefer the
AMaZE method though. DCB is similar to AMaZE, it also removes maze
artifacts.
Zoom in to at least 100% (1:1) and try all the demosaicing algorithms, see
which works best for you. Try them on sharp photos with fine detail and tiny
patterns, such as the wavy and repetitive fabric of a sweater (watch for maze
pattern artifacts), a distant brick wall, a distant round road sign (watch for
aliasing along the round edges), and test with both low and high ISO shots.
Use photos from your own camera; what’s best for Nikon raws is not what’s
best for Olympus raws.
False Color Suppression Steps
Sets the number of median filter passes applied to suppress demosaic
RawTherapee 4.0.12 User Manual
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