Ubuntu Manpage: pfshdrcalibrate - Create an HDR image or calibrate a response curve from a set of differently exposed

Provided by: pfstools_2.0.4-5build1_amd64

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 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 measurement 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". 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 Recognition (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-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 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.

--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 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 image 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 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 -s resp_mitsunaga.m >/dev/null

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

BUGS