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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>fakeread</title>
<meta http-equiv="content-type" content="text/html;
charset=ISO-8859-1">
<meta name="author" content="Graeme Gill">
</head>
<body>
<h2><b>spectro/fakeread</b></h2>
<h3>Summary</h3>
Simulate the measurement of a devices response, using an existing
device profile, or measured test point data set. The device profile
can be either an <a href="File_Formats.html#ICC">ICC</a> or <a
href="File_Formats.html#MPP">MPP</a> profile, or the data set can
be a <a href="File_Formats.html#.ti3">.ti3</a> file. A device link
separation or color space conversion can be applied before the
print/measure simulation, as well as device calibration or
inverse calibration curves.<br>
<br>
<b>fakeread</b> can be useful for creating a data set from an
existing profile to re-create a different style of profile (i.e.
create a cLUT profile from a matrix profile), for creating synthetic
data sets with known amounts of randomness for testing profile
creation against a perfectly known ideal, or for creating
verification test sets for checking colorimetric colorspace
emulation against.<br>
<br>
The options below are in the order of color processing that fakeread
performs.<br>
<h3>Usage</h3>
<small><span style="font-family: monospace;">fakeread [-options] </span></small><small><span
style="font-family: monospace;"></span></small><small><span
style="font-family: monospace;"></span><i style="font-family:
monospace;">profile.</i><span style="font-family: monospace;">[icm|mpp|ti3]
</span><i style="font-family: monospace;">inoutfile</i></small><small><span
style="font-family: monospace;"><br>
-v
[n]
Verbose mode [level]<br>
-e
flag
Video encode device input to sepration as:<br>
n
normal 0..1 full range RGB levels (default)<br>
t
(16-235)/255 "TV" RGB levels<br>
6
Rec601 YCbCr SD (16-235,240)/255 "TV" levels<br>
7
Rec709 1125/60Hz YCbCr HD (16-235,240)/255 "TV" levels<br>
5
Rec709 1250/50Hz YCbCr HD (16-235,240)/255 "TV" levels<br>
2
Rec2020 YCbCr UHD (16-235,240)/255 "TV" levels<br>
C
Rec2020 Constant Luminance YCbCr UHD (16-235,240)/255 "TV"
levels<br>
-p <i>separation.icm</i> Use device link separation
profile on input<br>
-E
flag
Video decode separation device output. See -e above<br>
-k <i>file.cal</i>
Apply calibration (include in .ti3 output)<br>
-i <i>file.cal</i>
Include calibration in .ti3 output, but don't apply it<br>
-K <i>file.cal</i>
Apply inverse calibration<br>
-r
level Add
average random deviation of <level>% to device values
(after sep. & cal.)<br>
-0
pow
Apply power to device chanel 0-9<br>
-b <i>output.icm</i> Apply
BT.1886-like mapping with effective gamma 2.2<br>
-b g.g:<i>output.icm</i> Apply BT.1886-like mapping with
effective gamma g.g<br>
-B <i>output.icm</i> Apply
BT.1886 mapping with technical gamma 2.4<br>
-B g.g:<i>output.icm</i> Apply BT.1886 mapping with
technical gamma g.g<br>
-I intent
r = relative colorimetric, a = absolute (default)<br>
-A
L,a,b
Scale black point to target Lab value<br>
-l
Output Lab rather than XYZ<br>
-s
Lookup </span></small><small><span style="font-family:
monospace;"><small><a style="font-family: monospace;"
href="File_Formats.html#MPP">MPP</a></small>
spectral values</span></small><br>
<small><span style="font-family: monospace;"><small><span
style="font-family: monospace;"> -R
level
Add average random deviation of <level>% to output PCS
values<br>
</span></small> -u
Make random deviations have uniform distributions rather than
normal<br>
-S
seed
Set random seed<br>
</span><span style="font-family: monospace;"> </span><i
style="font-family: monospace;">profile.</i><span
style="font-family: monospace;">[icm|mpp|ti3] </span><a
style="font-family: monospace;" href="File_Formats.html#ICC">ICC</a><span
style="font-family: monospace;">, </span><a style="font-family:
monospace;" href="File_Formats.html#MPP">MPP</a><span
style="font-family: monospace;"> or </span><a
style="font-family: monospace;" href="File_Formats.html#.ti3">.ti3</a><span
style="font-family: monospace;"> profile/file to use</span><br
style="font-family: monospace;">
<span style="font-family: monospace;"></span><i
style="font-family: monospace;">inoutfile</i><span
style="font-family: monospace;">
Base name for input[</span><a style="font-family:
monospace;" href="File_Formats.html#.ti1">.ti1</a><span
style="font-family: monospace;">]/output[</span><a
style="font-family: monospace;" href="File_Formats.html#.ti3">.ti3</a><span
style="font-family: monospace;">] file</span></small><br>
<b><br>
Examples</b><br>
<br>
fakeread profile.icm testvalues<br>
fakeread -p separation.icm profile.icm testvalues<br>
<h3>Comments<br>
</h3>
<a name="v"></a>The <span style="font-weight: bold;">-v</span> flag
reports extra information, e.g. on what BT.1886 option is doing. A
level > 1 will be more verbose.<br>
<br>
<a name="e"></a>The <b>-e</b> <i>flag</i> applies a Video encoding
to the input of the separation.<small><small><br>
<br>
n
normal 0..1 full range RGB levels (default)<br>
t
(16-235)/255 "TV" RGB levels<br>
6
Rec601 YCbCr SD (16-235,240)/255 "TV" levels<br>
7
Rec709 1125/60Hz YCbCr HD (16-235,240)/255 "TV" levels<br>
5
Rec709 1250/50Hz YCbCr HD (16-235,240)/255 "TV" levels<br>
2
Rec2020 YCbCr UHD (16-235,240)/255 "TV" levels<br>
C
Rec2020 Constant Luminance YCbCr UHD (16-235,240)/255 "TV" lev</small></small><br>
<br>
<a name="p"></a>The <span style="font-weight: bold;">-p</span> <b><i>separation.icm</i></b>
option enables a device to device value conversion before converting
to expected PCS values. This might be an ink separation of a video
calibration device link. The argument is the name of the ICC device
link that defines the separation.<br>
<br>
<a name="E"></a>The <b>-E</b> <i>flag</i> applies a Video decoding
to the output of the separation.<small><small> </small></small>See
<a href="#e"><b>-e</b></a> for the list of decodings.<br>
<br>
<a name="k"></a>The <b>-k file.cal</b> parameter specifies a
calibration file created by <a
href="printcal.html">printcal</a> or <a
href="dispcal.html">dispcal</a>, and the supplied calibration
curves will be applied to the chart device values after any
separation and before the device profile. This allows emulating a
system that uses per device channel calibration. The calibration
curves will also be included in the resulting .ti3 file, so that
they can be passed through to the ICC profile allowing accurate
computation of ink limits.<br>
<br>
<a name="i"></a> The <b>-i file.cal</b> parameter specifies a
printer calibration file created by <a
href="printcal.html">printcal</a> or <a
href="dispcal.html">dispcal</a>, and the
calibration curves will be included in the included in the resulting
.ti3 file, so that they can be passed through to the ICC profile, to
allow accurate computation of ink limits. The calibration <span
style="font-weight: bold;">is not applied</span> to tchart values.
<span style="font-weight: bold;">Note</span> that if the supplied
ICC profile contains VCGT calibration curves, that these will be
included in the resulting .ti3 by default.<br>
<br>
<a name="K"></a>The <b>-K</b> <b>file.cal</b> parameter specifies
a calibration file created by <a
href="printcal.html">printcal</a> or <a
href="dispcal.html">dispcal</a>, and the
inverse of the supplied calibration curves will be applied to the
chart device values after any separation and before the device
profile. This allows for undoing calibration curves that may be part
of a video calibration device link, so that the (calibrated device
value) device profile will work as expected.<br>
<br>
<a name="r"></a>The <span style="font-weight: bold;">-r</span>
parameter is a way of simulating instability in the behaviour of the
simulated printing system. The parameter supplied to the flag will
be used to scale a random offset added to the device values (after
any separation and calibration is applied). The offset will be a
normally distributed error with an average deviation of level%. A
typically value supplied might be 1.0 to simulate 1% randomness.<br>
<br>
<a name="0"></a>The <span style="font-weight: bold;">-0, -1, -2 ..
-9</span> parameters are a way of simulating changes in the
behavior of the simulated printing system. The parameter supplied to
the flag will be used to modify the device values (after any
separation, calibration and device randomness is applied) by raising
them to the power of the parameter. This applies a transfer curve to
the simulated device response.<br>
<br>
<a name="b"></a>The <b>-b output.icm</b> flag applies extra input
processing, applying <a
href="http://www.itu.int/rec/R-REC-BT.1886-0-201103-I">BT.1886</a>-like
video gamma mapping using an effective gamma of 2.2 by default, and
overridable using <b>-b g.g:output.icm</b> where <b>g.g</b> is the
gamma. <b>output.icm</b> is the display ICC profile that provides
the black point that the BT.1886 curves will target. The gamma is an
effective gamma, meaning that its effect on 50% input is the same as
that of a pure power curve, in spite of any black offset added by
BT.1886. This has the benefit of making the overall effect of
brightness independent of the black level of the display. Setting an
effective gamma other than 2.2 is one way of making the viewing
condition adjustment for the different conditions of video encoding
and decoding, or for modelling the source colorspace as a rendering
on a video display. BT.1886 will only work with matrix type input
profiles. Typically this will be used to create a verification test
set for checking the operation of a device link or 3dLut created
using <a href="collink.html">collink</a>, using the same BT.1886
parameters.<br>
<br>
<b><a name="B"></a></b>The <b>-B output.icm</b> flag applies extra
input processing, applying <a
href="http://www.itu.int/rec/R-REC-BT.1886-0-201103-I">BT.1886</a>-like
video gamma mapping using a gamma of 2.4 by default, and overridable
using <b>-B g.g:output.icm</b> where <b>g.g</b> is the gamma. <b>output.icm</b>
is the display ICC profile that provides the black point that the
BT.1886 curves will target. The gamma is the technical gamma, or
power applied to the input image, and this means that its effect on
50% input will depend on the black level of the display, making the
overall brightness somewhat unpredictable. For a more predictable
effect, use <b>-b</b>.<br>
<br>
<a name="I"></a>The <span style="font-weight: bold;">-I</span>
parameter allows changing the intent used in looking up the ICC
profile colors to relative colorimetric. This would <span
style="text-decoration: underline;">not</span> be used if you
intend to make a profile from the resulting .ti3 file, since
profiles are always made from absolute colorimetric measurement
values. Note that this flag does nothing if the profile is an MPP or
.ti3 file.<br>
<span style="font-weight: bold;"></span><br>
<a name="A"></a>The <span style="font-weight: bold;">-A</span>
parameter is a way of simulating devices that have a different black
point to the profile used. This only works if an ICC profile is
used, and scales the black point to the parameter value. This will
be done in XYZ space by default, and in L*a*b* space if the <a
href="#l"><span style="font-weight: bold;">-l</span></a> flag is
used.<br>
<br>
<a name="l"></a>The <span style="font-weight: bold;">-l</span> flag
causes the CIE output values to be L*a*b* rather than the default
XYZ values.<br>
<br>
<a name="s"></a>The <span style="font-weight: bold;">-s</span> flag
works if a spectral MPP file is being used as a device profile, and
causes the output to include spectral values.<br>
<br>
<a name="R"></a>The <span style="font-weight: bold;">-R</span>
parameter is a way of simulating instability in the behavior of the
simulated measuring system. The parameter supplied to the flag will
be used to scale a random offset added to the PCS values. The offset
will be a normally distributed error with an average deviation of
level%. A typically value supplied might be 1.0 to simulate 1%
randomness. <br>
<br>
<a name="u"></a>The <span style="font-weight: bold;">-u</span> flag
changes the distribution of the random offsets applied using the <span
style="font-weight: bold;">-r</span> or <span style="font-weight:
bold;">-R</span> flags, from the default standard deviation, to a
uniform deviation distribution. The level is still specified as an
average deviation.<br>
<br>
<a name="S"></a>The <span style="font-weight: bold;">-S</span>
parameter lets a particular random seed be used when generating
random offsets, so that the randomness can be made repeatable.
Normally a different seed will be used for each run. <br>
<br>
Fakeread is useful in creating artificial test value for testing <a
href="colprof.html">colprof</a>, as well as providing one path for
turning an MPP profile into an ICC profile. It can also be used to
create a reference file for verifying against. If a <a
href="File_Formats.html#.ti3">.ti3</a> file is specified instead
of an <a href="File_Formats.html#ICC">ICC</a> or <a
href="File_Formats.html#MPP">MPP</a> profile, then the closest
matching measured points in the .<a href="File_Formats.html#.ti3">.ti3</a>
are substituted for the test values in the <a
href="File_Formats.html#.ti1">.ti1</a> file on output. If the <a
href="File_Formats.html#.ti1">.ti1</a> file is a monochrome test
file with a White device value, then an RGB <a
href="File_Formats.html#ICC">ICC</a> profile, <a
href="File_Formats.html#MPP">MPP</a> or <a
href="File_Formats.html#.ti3">.ti3</a> may be used, and the White
values will be translated to equal RGB values. If the <a
href="File_Formats.html#.ti1">.ti1</a> file is a monochrome test
file with a Black device value, then a CMYK <a
href="File_Formats.html#ICC">ICC</a> profile, <a
href="File_Formats.html#MPP">MPP</a> or <a
href="File_Formats.html#.ti3">.ti3</a> may be used, and the Black
values will be translated to equal CMY = 0, K = grey values. <span
style="font-weight: bold;">Note</span> that any calibration within
a supplied ICC profile is <span style="text-decoration: underline;">not</span>
applied during the conversion, although it will be included in the
.ti3 output (see <span style="font-weight: bold;">-k</span> and <span
style="font-weight: bold;">-i</span> flags for how apply
calibration curves during the conversion and/or include a specific
calibration curves in the output).<br>
<br>
If a separation device profile is provided (e.g. from CMY ->
CMYK, or perhaps CMYK->CMYK, to simulate a color correction step
before "printing", or perhaps a Video RGB->RGB calibration link)
then this will be applied to the .ti1 device values, before
converting the the device values into .ti3 PCS values.<br>
<br>
<br>
<br>
<br>
</body>
</html>
|
