xenial (1) pfstmo_mantiuk08.1.gz
NAME
pfstmo_mantiuk08 - Display adaptive tone mapping
SYNOPSIS
pfstmo_mantiuk08 [--display-function <df-spec>] [--display-size=<size-spec>] [--color-saturation <float>]
[--contrast-enhancement <float>] [--white-y=<float>] [--fps=<frames-per-second>] [--output-tone-
curve=<file name>] [--verbose] [--help]
DESCRIPTION
This command applies the display adaptive tone mapping, which attempts to preserve contrast of an input
(HDR) image as close as possible given the characteristic of an output display. Use this tone mapping
operator if you want to preserve original image appearance, or slightly enhance contrast (-e option)
while maintaining the natural look of images. The operator can also compensate for ambient light
reflections on a screen, and for varying dynamic range and brightness of a display. The operator is
suitable for video sequences as it prevents high-frequency changes in tone-curve between consecutive
frames, which would result in flickering. Note that the temporal filtering is always active and there is
no need to specify an argument to switch it on.
More details can be found in:
Rafal Mantiuk, Scott Daly and Louis Kerofsky.
Display Adaptive Tone Mapping.
In: ACM Transactions on Graphics 27 (3), 2008.
http://www.mpi-inf.mpg.de/resources/hdr/datmo/
If you find this TMO useful in your research project, please cite the paper above.
This operator also employs color correction mechanism from:
Radoslaw Mantiuk, Rafal Mantiuk, Anna Tomaszewska, Wolfgang Heidrich.
Color Correction for Tone Mapping.
In: Computer Graphics Forum (Proc. of EUROGRAPHICS'09), 28(2), 2009.
http://zgk.wi.ps.pl/color_correction/
The result of this TMO does not require gamma correction.
OPTIONS
--display-function <df-spec>, -d <df-spec>
To adapt tone-mapping to different displays, this operator must be provided a display function.
The display function describes how output luminance of a display changes with pixel values. If no
parameter is given, the command assumes -df pd=lcd (see Pre-defined display below). There are
several ways to specify the display function:
Gamma-gain-black-ambient display model
g=<float>:l=<float>:b=<float>:k=<float>:a=<float>[:n=<float>]
Gamma-gain-black-ambient model can approximate a range of displays and is a compact way to specify
a display function. It assumes that a display function has the following form:
L_d(I) = (l-b)*I^gamma + b + k/pi*a
The parameters are as follows:
g - gamma or exponent of a display function (default 2.2, usually from 1.8 to 2.8)
l - peak luminance of a display in cd/m^2 (default 100, from 80 for CRTs to 500 or more for
newer displays)
b - black level, which is luminance of a black pixel when the display is on (default 1, usually
from 0.3 to 1 cd/m^2)
k - reflectivity of a screen (assuming that it is diffuse) (default 0.01, usually about 0.01 (1%)
for LCD displays, more for CRTs)
a - ambient illumination in lux. Typical values are:
50 lux Family living room (dim, default)
400 lux
A brightly lit office
32000 lux
Sunlight on an average day (min.)
100000 lux
Sunlight on an average day (max.)
Pre-defined display
pd=<display_type>
Use pre-defined display type. This options are for convenience only and they do not mean to
accurately model the response of a particular display. The following display types are
recognized:
lcd_office (g=2.2, l=100, b=0.8, k=0.01, a=400 )
lcd set to "office" mode seen in bright environment
lcd (g=2.2, l=200, b=0.8, k=0.01, a=60 )
typical lcd seen in dim environment (default)
lcd_bright (g=2.6, l=500, b=0.5, k=0.01, a=10 )
newer LCD TV seen in dark environment
crt (g=2.2, l=80, b=1, k=0.02, a=60 )
CRT monitor seen in dim environment
The parameters in the parenthesis are the same as for the gamma-gain-black-ambient model explained
above.
Lookup-table
lut=<file>
This is the most accurate specification of the display response function, but requires measuring
it with a luminance meter. The lookup table should account also for ambient light, so that it is
recommended to use the luminance meter that can measure screen luminance from a distance, such as
Minolta LS-100 (as opposed to those that use rubber tube touching a display that eliminates the
influence of ambient light). The <file> must be a comma-separated text file in a format (CSV) with
two columns: first column represents pixel values (from 0.0 to 1.0) and the second physical
luminance in cd/m^2. Both the pixel value and the luminance should increase in each raw.
--display-size=<size-spec>, -s=<size_spec>
Specifies how large the image appears to a viewer and what is the viewing distance. If no
parameter is given, -s ppd=30 is assumed. Since this tone-mapper is global, display size has
moderate effect on the resulting images and thus skipping this parameter should not do much harm.
There are two ways to specify image size:
vres=<lines>:vd=<screen_heights>[:d=<meters>]
vres - screen's vertical resolution in lines, for example 1024.
vd - viewing distance specified as multiplies of screen height. For example if the
display is seen from 0.5m and the height of its screen is 25cm, vd=2.
d - (optional) viewing distance in meters. This is to account for lower eye's
sensitivity for larger viewing distances (although the effect is negligible). By
default -d=0.5 is assumed.
ppd=<pixels_per_visual_degree>[:d=<meters>]
ppd - how many pixels spans one visual degree.
d - (optional) viewing distance in meters. This is to account for lower eye's
sensitivity for larger viewing distances (although the effect is negligible). By
default -d=0.5 is assumed.
--color-saturation <float>, -c <float>
Decrease or increase color saturation after tone mapping. Default value -c=1 attempts to preserve
color appearance of the original image. Use values >1 to increase and <1 to decrease color
saturation.
--contrast-enhancement <float>, -e <float>
By default this tone-mapper attempts to preserve contrast of an input image (-e=1). This parameter
controls whether the contrast of an input image should be enhanced before tone-mapping. For
example -e=1.15 boosts contrast by 15%. Note that if a target display does not offer sufficient
dynamic range, contrast may be enhanced only for selected tone-values (those that dominate in an
image) or not enhanced at all.
--white-y=<float>, -y=<float>
Tells the tone-mapper what luminance level in the input image should be mapped to the maximum
luminance of a display. Since HDR images contain only relative luminance information, tone-mapper
does not know how bright should be the scene. This option is meant to fix this problem by
providing tone-mapper with the information what luminance level in an input image should be
perceived as a diffuse white surface. Default is none, which means that no such mapping will be
enforced and tone-mapper is free to find an optimal brightness for a given image. This is a
recommended setting for HDR images. Setting --white-y could be necessary for dark scenes, which
could be made too bright by the tone-mapper. The value of this parameter can be also passed in
pfsstream as a tag WHITE_Y. pfstools 1.7 and newer sets set this tag automatically for LDR images.
The command line option overrides the value of the pfstream tag.
--fps=<frames-per-second>, -f=<frames-per-second>
Set the frame rate of the input sequence. Default is 25. Currently only 3 values are supported:
25, 30 and 60. This parameter controls temporal filter that makes sure the resulting sequence is
coherent in time. This reduces the likelihood of a visible flicker.
--output-tone-curve=<file name>, -o=<file name>
Write tone-curves to a text file. This option is mainly for debugging purposes, but can be used to
visualize computed tone-curves. The tone-curve data is stored in a comma separated text file
(CSV), consisting of three columns: frame number, log10 of input luminance factor, log10 of the
resulting display luminance, and the pixel value (0-1).
--verbose, -v
Print additional information during program execution.
--quiet, -q
Do not display progress report.
--help, -h
Print list of commandline options.
EXAMPLES
pfsin memorial.hdr | pfstmo_mantiuk08 -d pd=crt | pfsout memorial.png
Tone map memorial image for a CRT display and store the result in the PNG format.
pfsin memorial.hdr | pfstmo_mantiuk08 -d g=2.6:l=500:b=0.5:k=0.01:a=10 | pfsview
Tone map memorial image for a display that has a 2.2 gamma, the peak luminance of 500 cd/m^2, the
black level of 0.5 cd/m^2, the panel reflectivity of 1% (0.01) and is seen under the illumination
of 10 lux.
pfsin bridge.jpg --linear | pfsclamp --min 0.007 | pfstmo_mantiuk08 -v | pfsview
Enhance the low-dynamic range image 'bridge' and view the result. pfsclamp command reduces noise
for low code values.
pfsin frame%05d.exr | pfstmo_mantiuk08 -d pd=lcd_bright --fps 30 | pfsout out_frame%04d.png
Tone-map video sequence at 30 frame-per-second frame rate.
pfsin *.exr | pfstmo_mantiuk08 | pfsview
Tone-map and display *.exr HDR images in the current directory.
pfsin *.exr | pfstmo_mantiuk06 | pfsgamma -g 0.8 | pfstmo_mantiuk08 | pfsview
It is possible to stack a TMO that sharpens images (pfstmo_mantiuk06) with the contrast preserving
TMO (pfstmo_mantiuk08) to get new interesting results.
SEE ALSO
pfsin(1) pfsout(1) pfsview(1)
BUGS
Please report bugs and comments to the pfstools discussion group
(http://groups.google.com/group/pfstools).
pfstmo_mantiuk08(1)