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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 differ-
       ently exposed images supplied in	PFS stream.

       When used with 8bit images, luminance in	the output  HDR	 image	corre-
       sponds  to  real	 world	values in [cd/m^2] provided that hdrgen	script
       contained 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 one to choose from	predefined response curves.  This  can
	      be  used	either to apply	this response or use it	as an initial-
	      ization  for  automatic  self-calibration.  Predefined  response
	      curves  are: "linear", "gamma", "log". Default is	"linear". This
	      option can be used only with Robertson method.

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

	      Type of automatic	self-calibration method	used for  recovery  of
	      the  response  curve and/or type of method used for HDR merging.
	      Accepted types include: "robertson", "mitsunaga".	"robertson" is
	      the  default and recommended algorithm (see commends in the Bugs
	      section below). 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  Recogni-
	      tion (CVPR'99). Volume 1,	p. 1374

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

	      Sigma  value  for	 the Gaussian used as a	weighting function (in
	      the range	0-1). Applies to Robertson02 algorithm.	Default	value:
	      0.2

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

	      Use  response  curve  saved in the matlab	format file. Turns off
	      automatic	 self-calibration.  Uses  Robertson02  or  Mitsunaga99
	      model to apply the response curve	(see -c	option).

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

	      Saves  the response curve	calculated during automatic self-cali-
	      bration 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  for  Robertson method	is 256
	      since LDR	images are by default scaled to	0..1.  This  value  is
	      set to 1.0 for Mitsunaga method.

       --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	samples	used during the	self-calibration in  Mitsunaga
	      algorithm. Default is 50000.

       --deghosting, -d

	      EXPERIMENTAL.  Try to use	a simple rejection criterion to	reduce
	      ghosting artifacts due to	movement in dynamic  scenes.  This  is
	      currently	not well implemented to	the results can	be disappoint-
	      ing.

       --luminance, -Y

	      Recovery of response curve will be performed for luminance chan-
	      nel only.

       --verbose

	      Print additional information during program execution.

       --help

	      Print list of command line options.

EXAMPLES
       pfsinme *.JPG | pfshdrcalibrate -v -s response.m	| pfsview

	      Recover  the  response  curve  from set of all JPEG files	in the
	      current directory	and save it to response.m file.	 To  view  the
	      response curve, use pfsplotresponse command.

       pfsinme	*.CR2  |  pfssize   --maxx 1200	| pfshdrcalibrate -r linear -v
       --bpp 16	| pfsout result.exr

	      Read Camera RAW images (from Canon), resize them so that the im-
	      age  width  is equal or less 1200	pixels,	merge them into	an HDR
	      image using all 16 bits and save as an Open EXR image.

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

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

       pfsinhdrgen  sample.hdrgen  |  pfshdrcalibrate  -c  mitsunaga  -samples
       100000 -s resp_mitsunaga.m >/dev/null

	      Create an	HDR image from exposures defined in sample.hdrgen  us-
	      ing  the	mitsunaga  self-calibration method with	100000 samples
	      and save it to "resp_mitsunaga.m".

SEE ALSO
       pfsplotresponse(1)  pfsinhdrgen(1)  jpeg2hdrgen(1)  pfsview(1)  pfsind-
       craw(1) pfsabsolute(1) pfsglview(1)

BUGS
       Currently Mitsunaga and Nayar's method does not produce reliable	camera
       response	curves.	Robertson's method should be used instead.

       Robertson's method may banding or wrong colors in  strongly  over-satu-
       rated  and  under-saturated  areas. For best results, there should be a
       sufficient numbers of exposures in which	no pixels is over-  or	under-
       saturated in all	the exposures. It is possible to fix these issues with
       some heuristics (as most	HDR merging software does),  but  it  is  cur-
       rently  not  done  in this release. pfscalibration was meant to be used
       for research purposes and getting accurate  result  is  more  important
       than generating good looking images. The	heuristics could hide the well
       visible artifacts, but would also introduce error to the	measurements.

       For any other issues please report bugs and comments on	implementation
       to the discussion group http://groups.google.com/group/pfstools

							    pfshdrcalibrate(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXAMPLES | SEE ALSO | BUGS

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