Revision as of 13:19, 24 January 2011

Skipping

Also called "Decimation" means that a certain amount of photosites is not read out ->skipped (horizontally, vertically or in both axis). This reduces resolution of the resulting image but introduces subsampling artifacts. This is an on-sensor-feature.

Binning

Pixel Binning refers to the method of combining (averaging or summing) charges of blocks of neighbouring same-color-photosites. This is an on-sensor-feature.

Using both skipping and binning at the same time reduces subsampling artifacts but does not eliminate them completely.

Articles describing "Binning"

http://www.ccd.com/ccd103.html

http://www.imagingu.com/articles/binning.html

http://www.echenique.com/index.php/2009/05/16/phaseone-sensor-pixel-binning-and-the-future-of-digital-photography/

http://www.ptgrey.com/support/kb/index.asp?a=4&q=163

Pixel Binning in Elphel Cameras

Using Skipping/Binning you can:

• lower the resolution of an image while using the same sensor area
• achieving higher FPS for the same resulting resolution
• decrease image noise (averaging) or increase light sensitivity (summing)

But be careful: Binning/Decimation effectively result in a certain amount of subsampling artifacts.

Binning Modes

The "normal" Binning mode averages the charges from photosites thus reducing noise in the image but not altering light sensitivity. [1]

There is an alternative mode that sums up the charges and therefore makes the binned pixel more light sensitive. [2]

In Elphel Camera (since 8.X Software) the different binning modes can be set at http://*cameraIP*/parsedit.php?embed=0.18&SENSOR_REGS32

The default value is "0x40" which means averaging binning mode.

If you set it to "0x60" you switch to summing binning mode and will get increased light sensitivity.

Using PHP you can access this register with:

echo elphel_get_P_value(ELPHEL_SENSOR_REGS+32);