1pfshdrcalibrate(1) General Commands Manual pfshdrcalibrate(1)
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6 pfshdrcalibrate - Create an HDR image or calibrate a response curve
7 from a set of differently exposed images supplied in PFS stream.
8
11 pfshdrcalibrate [--response <type>] [--calibration <type>] [--gauss
12 <val>] [--response-file <filename.m>] [--save-response <filename.m>]
13 [--multiplier <val>] [--bpp <val>] [--luminance] [--samples <val>]
14 [--help] [--verbose]
15
18 Create an HDR image or calibrate a response curve from a set of differ‐
19 ently exposed images supplied in PFS stream.
20 When used with 8bit images, luminance in the output HDR image corre‐
22 sponds to real world values in [cd/m^2] provided that hdrgen script
23 contained correct information on exposure time, aperture and iso speed.
24 Note that sometimes ISO speed indicated by camera does not correspond
25 to standard (ISO-100 is in fact ISO-125).
26 The accuracy of absolute calibration has not been thoroughly tested
28 with different camera models, however one can expect the relative mea‐
29 surement error below 8%. Use pfsabsolute in case of systematic error.
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33 --response <type>, -r <type>
34 Allows to choose from predefined response curves. This can be
36 used either to apply this response or use it as an initializa‐
37 tion for automatic self-calibration. Predefined response curves
38 are: "linear", "gamma", "log". Default is "linear".
39 --calibration <type>, -c <type>
42 Type of automatic self-calibration method used for recovery of
44 the response curve. Accepted types include: "none", "robertson",
45 "mitsunaga". Default is "robertson". In case "none" is chosen, a
46 predefined response will be used, without self-calibration. More
47 infomation on the algorithms can be found in:
48 M.A. Robertson, S. Borman and R.L. Stevenson
50 Dynamic range improvement through multiple exposures
51 In: Proc. of International Conference on Image Processing 1999
52 (ICIP 99), pp 159-163 vol.3
53 and
55 T. Mitsunaga and S. K. Nayar
57 Radiometric Self Calibration
58 In: Proc on IEEE Conf. on Computer Vision and Pattern Recogni‐
59 tion (CVPR'99). Volume 1, p. 1374
60 --gauss <val>, -g <val>
62 Sigma value for the Gaussian used as a weighting function.
64 Applies to Robertson02 algorithm. Default value: 16.0f
65 --response-file <filename.m>, -f <filename.m>
68 Use response curve saved in the matlab format file. Turns off
70 automatic self-calibration. Uses Robertson02 model to apply the
71 response curve.
72 --save-response <filename.m>, -s <filename.m>
75 Saves the response curve calculated during automatic self-cali‐
77 bration stage in a matlab format file. Can be later reused for
78 set of images captured with given camera. Also works fine for
79 plotting with gnuplot.
80 --multiplier <val>, -m <val>
83 Input multiplier value. Can be used to manipulate the range of
85 source exposures. Default value is 256 since LDR images are by
86 default scaled to 0..1.
87 --bpp <val>, -b <val>
90 Number of bits per pixel in input data from the camera. Default
92 value is 8.
93 --samples <val>, -p <val>
96 Number of sample pixels used in inverse response computations in
98 Mitsunaga algorithm. Default is 50000.
99 --fix-saturated, -x
102 Use this option if you see black pixels in overexposed / satu‐
104 rated areas. The black pixels are visible if all exposures con‐
105 tain pixel values that are outside reliable range (are under- or
106 over-exposed). This flag gives non-zero weight for the brightest
107 and the darkest pixels, thus avoiding zero-weighted pixels. Note
108 that the calculated luminance values for these pixels are not
109 reliable.
110 --luminance, -Y
113 Recovery of response curve will be performed for luminance chan‐
115 nel only.
116 --verbose
119 Print additional information during program execution.
121 --help
123 Print list of commandline options.
125
128 pfsinhdrgen sample.hdrgen | pfshdrcalibrate -v -s response.m
129 Recover the response curve from set of exposures defined in sam‐
131 ple.hdrgen and save it to response.m file. To view the response
132 curve, run gnuplot and write 'plot "response.m"'.
133 pfsinhdrgen sample.hdrgen | pfshdrcalibrate -x -f response.m | pfsview
136 Create an HDR image from exposures defined in sample.hdrgen
138 using the response curve "response.m" and view it. Fix the prob‐
139 lem with black values given to overexposed pixels.
140 pfsinhdrgen sample.hdrgen | pfshdrcalibrate | pfsview
143 Create an HDR image from exposures defined in sample.hdrgen
145 using the default self-calibration method and view it.
146 pfsinhdrgen sample_dcraw.hdrgen | pfshdrcalibrate -b 16 -r linear -c
149 none | pfsview
150 Given that the script sample_dcraw.hdrgen refers to camera RAW
152 files (see pfsindcraw), this example will generate an HDR image
153 assuming a linear response.
154 pfsinhdrgen sample.hdrgen | pfshdrcalibrate | pfsview
157 Create an HDR image from exposures defined in sample.hdrgen
159 using the default self-calibration method and view it.
160 pfsinhdrgen sample.hdrgen | pfshdrcalibrate -c mitsunaga -samples
163 100000 | pfsglview
164 Create an HDR image from exposures defined in sample.hdrgen
166 using the mitsunaga self-calibration method with 100000 samples
167 and view it in pfsglview.
168
171 pfsinhdrgen(1) jpeg2hdrgen(1) pfsview(1) pfsindcraw(1) pfsabsolute(1)
172 pfsglview(1)
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175 Please report bugs and comments on implementation to Grzegorz Krawczyk
176 <gkrawczyk@users.sourceforge.net>.
177 pfshdrcalibrate(1)