# Interpolation



## PASM (Mar 19, 2011)

I'm using UFRAW and there is an option for choosing color interpolation method.

The choices are:

AHD
VNG
VNG four color
PPG
Bilinear

I'm going to be reading-up about these this evening but if anyone has any knowledge to share about choosing, please chip-in. I'm developing some images shot in NEF (Adobe1998), that will be sized for the web, if it's relevant.


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## Garbz (Mar 19, 2011)

These options define the interpolation of the beyer pattern on the sensor back to a real image. A camera sensor doesn't have 10million full colour pixels in a 10mpxl sensor, instead they have 2.5m red, 5m green, and 2.5m blue laid out in the pattern:

RGBGRGBG
GBGRGBGR
BGRGBGRG
GRGBGRGB

I've read up about them a while ago and then actually realized it was pointless. Zoom in on the image, and pick the one that looks best and stick with it. For the most part UFRAW even providing you with the option is is a bonus caused by developers fighting between speed vs accuracy.


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## PASM (Mar 20, 2011)

Thanks. I didn't detect much (if any) real change, visually, whichever I selected.


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## PASM (Mar 20, 2011)

UFRaw - User Guide

Interpolation

After setting the white balance UFRaw interpolates the Bayer pattern.
AHD interpolation is the Adaptive Homogeneity-Directed interpolation. It is the default interpolation.
VNG interpolation uses threshold-based Variable Number of Gradients interpolation. This used to be the default interpolation and it is still very good.
VNG four color interpolation should be used if you get Bayer pattern artifacts in your photo (see DCRaw's FAQ for more details).
PPG interpolation stands for Patterned Pixel Grouping interpolation. It is almost as good as all of the above and much faster.
Bilinear interpolation is a very basic interpolation but it is much faster.


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## Garbz (Mar 21, 2011)

Yeah. one way you can read that is unless you have speed issues opening your photos don't touch the setting


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