ALLIED Vision Technologies Pike F-1600 - Manual (Page 153)

Description of the data path
PIKE Technical Manual V5.1.2
153
Shading correction
Shading correction is used to compensate for non-homogeneities caused by
lighting or optical characteristics within specified ranges.
To correct a frame, a multiplier from 1...2 is calculated for each pixel in

1/256 steps: this allows for shading to be compensated by up to 50%.
Besides generating shading data off-line and downloading it to the camera, the
camera allows correction data to be generated automatically in the camera
itself.
Building shading image in Format_7 modes
horizontal Binning/sub-sampling is always done after shading correction. Shading is
always done on full horizontal resolution. Therefore shading image has always
to be built in full horizontal resolution.
vertical Binning/sub-sampling is done in the sensor, before shading correction. There-
fore shading image has to be built in the correct vertical resolution.
First example
4 x horizontal binning, 2 x vertical binning

 build shading image with 0 x horizontal binning and 2 x vertical binning
Second example
2 out of 16 horizontal sub-sampling, 2 out of 8 vertical sub-sampling

 build shading image with 0 x horizontal binning and 2 out of 8 vertical sub-
sampling
How to store shading image
There are two storing possibilities:
• After generating the shading image in the camera, it can be uploaded to
the host computer for nonvolatile storage purposes.
Note

• Shading correction does not support the mirror function.
• If you use shading correction, don’t change the mirror
function.
• Due to binning and sub-sampling in the Format_7 modes
read the following hints to build shading image in
Format_7 modes.
Note

Build shading image always with the full horizontal resolu-
tion (0 x horizontal binning / 0 x horizontal sub-sampling),
but with the desired vertical binning/sub-sampling.