pfshdrcalibrate(1)					      General Commands Manual						pfshdrcalibrate(1)

NAME

       pfshdrcalibrate - Create an HDR image or calibrate a response curve from a set of differently exposed images supplied in PFS stream.

SYNOPSIS

       pfshdrcalibrate	[--response  <type>]  [--calibration <type>] [--gauss <val>] [--response-file <filename.m>] [--save-response <filename.m>]
       [--multiplier <val>] [--bpp <val>] [--luminance] [--samples <val>] [--help] [--verbose]

DESCRIPTION

       Create an HDR image or calibrate a response curve from a set of differently exposed images supplied in PFS stream.

       When used with 8bit images, luminance in the output HDR image corresponds to real world values in [cd/m^2] provided that hdrgen script con-
       tained  correct information on exposure time, aperture and iso speed. Note that sometimes ISO speed indicated by camera does not correspond
       to standard (ISO-100 is in fact ISO-125).

       The accuracy of absolute calibration has not been thoroughly tested with different camera models, however one can expect the relative  mea-
       surement error below 8%. Use pfsabsolute in case of systematic error.

OPTIONS

       --response <type>, -r <type>

	      Allows  to choose from predefined response curves. This can be used either to apply this response or use it as an initialization for
	      automatic self-calibration. Predefined response curves are: "linear", "gamma", "log". Default is "linear".

       --calibration <type>, -c <type>

	      Type of automatic self-calibration method used for recovery of the response curve.  Accepted  types  include:  "none",  "robertson",
	      "mitsunaga".  Default  is  "robertson". In case "none" is chosen, a predefined response will be used, without self-calibration. More
	      infomation on the algorithms can be found in:

	      M.A. Robertson,  S. Borman and R.L. Stevenson
	      Dynamic range improvement through multiple exposures
	      In: Proc. of International Conference on Image Processing 1999 (ICIP 99), pp 159-163 vol.3

	      and

	      T. Mitsunaga and S. K. Nayar
	      Radiometric Self Calibration
	      In: Proc on IEEE Conf. on Computer Vision and Pattern Recognition (CVPR'99). Volume 1, p. 1374

       --gauss <val>, -g <val>

	      Sigma value for the Gaussian used as a weighting function. Applies to Robertson02 algorithm. Default value: 16.0f

       --response-file <filename.m>, -f <filename.m>

	      Use response curve saved in the matlab format file. Turns off automatic  self-calibration.  Uses	Robertson02  model  to	apply  the
	      response curve.

       --save-response <filename.m>, -s <filename.m>

	      Saves  the response curve calculated during automatic self-calibration stage in a matlab format file. Can be later reused for set of
	      images captured with given camera. Also works fine for plotting with gnuplot.

       --multiplier <val>, -m <val>

	      Input multiplier value. Can be used to manipulate the range of source exposures. Default value  is  256  since  LDR  images  are	by
	      default scaled to 0..1.

       --bpp <val>, -b <val>

	      Number of bits per pixel in input data from the camera. Default value is 8.

       --samples <val>, -p <val>

	      Number of sample pixels used in inverse response computations in Mitsunaga algorithm. Default is 50000.

       --fix-saturated, -x

	      Use  this  option  if  you  see black pixels in overexposed / saturated areas. The black pixels are visible if all exposures contain
	      pixel values that are outside reliable range (are under- or over-exposed). This flag gives non-zero weight for the brightest and the
	      darkest pixels, thus avoiding zero-weighted pixels. Note that the calculated luminance values for these pixels are not reliable.

       --luminance, -Y

	      Recovery of response curve will be performed for luminance channel only.

       --verbose

	      Print additional information during program execution.

       --help

	      Print list of commandline options.

EXAMPLES

       pfsinhdrgen sample.hdrgen | pfshdrcalibrate -v -s response.m

	      Recover  the  response  curve  from  set	of exposures defined in sample.hdrgen and save it to response.m file. To view the response
	      curve, run gnuplot and write 'plot "response.m"'.

       pfsinhdrgen sample.hdrgen | pfshdrcalibrate -x -f response.m | pfsview

	      Create an HDR image from exposures defined in sample.hdrgen using the response curve "response.m" and view it. Fix the problem  with
	      black values given to overexposed pixels.

       pfsinhdrgen sample.hdrgen | pfshdrcalibrate | pfsview

	      Create an HDR image from exposures defined in sample.hdrgen using the default self-calibration method and view it.

       pfsinhdrgen sample_dcraw.hdrgen | pfshdrcalibrate -b 16 -r linear -c none | pfsview

	      Given  that  the	script	sample_dcraw.hdrgen  refers  to camera RAW files (see pfsindcraw), this example will generate an HDR image
	      assuming a linear response.

       pfsinhdrgen sample.hdrgen | pfshdrcalibrate | pfsview

	      Create an HDR image from exposures defined in sample.hdrgen using the default self-calibration method and view it.

       pfsinhdrgen sample.hdrgen | pfshdrcalibrate -c mitsunaga -samples 100000 | pfsglview

	      Create an HDR image from exposures defined in sample.hdrgen using the mitsunaga self-calibration method with 100000 samples and view
	      it in pfsglview.

SEE ALSO

       pfsinhdrgen(1) jpeg2hdrgen(1) pfsview(1) pfsindcraw(1) pfsabsolute(1) pfsglview(1)

BUGS

       Please report bugs and comments on implementation to Grzegorz Krawczyk <gkrawczyk@users.sourceforge.net>.

																pfshdrcalibrate(1)