GSP
Quick Navigator

Search Site

Unix VPS
A - Starter
B - Basic
C - Preferred
D - Commercial
MPS - Dedicated
Previous VPSs
* Sign Up! *

Support
Contact Us
Online Help
Handbooks
Domain Status
Man Pages

FAQ
Virtual Servers
Pricing
Billing
Technical

Network
Facilities
Connectivity
Topology Map

Miscellaneous
Server Agreement
Year 2038
Credits
 

USA Flag

 

 

Man Pages


Manual Reference Pages  -  PFSHDRCALIBRATE (1)

NAME

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

CONTENTS

Synopsis
Description
Options
Examples
Bugs

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".

--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>.
Search for    or go to Top of page |  Section 1 |  Main Index


PFSHDRCALIBRATE (1) -->

Powered by GSP Visit the GSP FreeBSD Man Page Interface.
Output converted with manServer 1.07.