Display test patches on a monitor, read the colorimetric value
result with the colorimeter, and create the chart readings file. The
type of instrument is determined by the communication port selected.
Emission and display measurement instruments are supported.
If you want to read a display manually rather than automatically,
see chartread and the -d option.
-display displayname [X11 only] Choose X11 display
[X11 only]Choose the display from the following list (default
for VideoLUT access.
Display via a web server at port (default 8080)
[MSWin] Display via MadVR Video Renderer
Display via n'th ChromeCast (default 1, ? for list)
communication port from the following list (default 1)
Use telephoto mode (ie. for a projector) (if available)
type - instrument specific list to choose from.
Load calibration file into display while reading
calibration file to test values while reading
[MSWin] Enable MadVR color management (3dLut)
Save spectral information (default don't
-P ho,vo,ss[,vs] Position
test window and scale it
1.0 = right/bottom etc.
2.0 = double etc.
ss,vs: = optional horizontal, vertical scale.
Fill whole screen with black background
encode output as (16-235)/255 "TV" levels
on test window
Run calibration first
Disable initial calibration of instrument if possible
Use high resolution spectrum mode (if
Apply Colorimeter Correction Matrix
Spectral Samples for calibration
Choose CIE Observer for spectrometer or CCSS
1931_2 (def.), 1964_10, S&B 1955_2, shaw,
J&V 1978_2, 1964_10c
Override measured refresh rate with rate Hz
Use non-adaptive integration time mode (if available).
Don't wait for the instrument to be placed on
"command" each time a color is set
"command" each time a color is measured
none, h = HW, x = Xon/Xoff
diagnostics to stderr
Base name for input[.ti1]/output[.ti3] file.
dispread -c1 -i92 mycrt
This is the tool for exercising a display, in order to measure its
color characteristics. The device test colors are defined by the
outfile.ti1 file, while the resulting device+colorimetric and
optional spectral readings are stored in the outfile.ti3 file.
Display calibration curves can be applied during the measurements,
and the curves included in the resulting .ti3 data file using the -kflag. See dispcal for information on how to
calibrate the display before profiling it. For best results, you
should run this against a neutral grey desktop background, and avoid
having any bright images or windows on the screen at the time you
The -v flag reports progress information.
When running on a UNIX based system that used the X11 Windowing
System, dispread will by default use the $DISPLAY
environment variable to determine which display and screen to read
from. This can be overridden by supplying an X11 display name to the
-display option. Note that
if Xinerama is active, you can't select the screen using $DISPLAY or
-display, you have to select it using the -d parameter.
default the main display will be the location of the test window. If
the system has more than one display or screen, an alternate
display/screen can be selected with the -d parameter. If you invoke dispread so as to display the
usage information (i.e. "dispread -?" or "dispread --"), then the
discovered displays/screens will be listed. Multiple displays may
not be listed, if they appear as a single display to the operating
system (ie. the multi-display support is hidden in the video card
driver). On UNIX based system that used the X11 Windowing System,
the -d parameter will
override the screen specified by the $DISPLAY or -display parameter.
On X11 the inability to access VideoLUTs could be because you are
trying to access a remote display, and the remote display doesn't
support the XF86VidMode extension, or perhaps you are running
multiple monitors using NVidia TwinView, or MergedFB, and trying to
access anything other than the primary monitor. TwinView and
MergedFB don't properly support the XF86VidMode extension for
multiple displays. You can use dispwin -r
to test whether the VideoLUTs are accessible for a particular
display. See also below, on how to select a different display for
VideoLUT access. Also note that dispcal will fail if the Visual
depth doesn't match the VideoLUT depth. Typically the VideoLUTs have
256 entries per color component, so the Visual generally needs to be
24 bits, 8 bits per color component.
Because of the difficulty cause by TwinView and
MergedFB in X11 based systems, you can optionally specify a separate
display number after the display that is going to be used to present
test patches, for accessing the VideoLUT hardware. This must be
specified as a single string, e.g. -d
1,2 . Some experimentation may be needed using dispwin on such systems, to discover what
screen has access to the VideoLUT hardware, and which screens the
test patches appear on. You may be able to calibrate one screen, and
then share the calibration with another screen. Profiling can be
done independently to calibration.
-dweb:port starts a
standalone web server on your machine, which then allows a local or
remote web browser to display the the color test patches. By default
port 8080 is used, but this
can be overridden by appending a :
and the port number i.e. -dweb:8001.
The URL will be http://
then name of the machine or its I.P. address followed by a colon and
the port number - e.g something like http://192.168.0.1:8080. If you use the verbose
option (-v) then a likely
URL will be printed once the server is started, or you could run ipconfig (MSWin) or /sbin/ifconfig (Linux or OS X)
and identify an internet address for your machine that way.
work. You may have to modify any firewall to permit port 8080 to be
accessed on your machine.
Note that if you use this method of displaying test patches, that
there is no access to the display VideoLUTs and that the colors will
be displayed with 8 bit per component precision, and any
screen-saver or power-saver will not be disabled. You will also be
at the mercy of any color management applied by the web browser, and
may have to carefully review and configure such color management.
See the -o flag for an explanation of
the implications of having no access to the VideoLUTs.
[MSWin only] causes test patches to be displayed using the MadVR
video renderer. Note that will have to start MadTPG before
running dispread, and that while you can adjust the "Test Pattern
Configuration" controls, you should not normally alter the
"Existing Calibration" controls, as dispread will set these
appropriately. See also -V flag.
-dcc or -dcc:no
causes test patches to be displayed using and available ChromeCast to
your TV. Use -dcc:? to display a list of ChromeCasts on your
local network. Note that the ChromeCast as a test patch source is
probably the least accurate of your choices, since it
up-samples the test patch and transforms from RGB to YCC and back,
but should be accurate within ± 1 bit. You may have to modify any
firewall to permit port 8081 to be accessed on your machine if it
falls back to the Default receiver (see installation
instructions for your platform).
instrument is assumed to communicate through a USB or serial
communication port, and the port can be selected with the -c
option, if the instrument is not connected to the first port. If you
invoke dispread so as to
display the usage information (i.e. "dispread -?" or "dispread --"),
then the discovered USB and serial ports will be listed. On
UNIX/Linux, a list of all possible serial ports are shown, but not
all of them may actually be present on your system.
The -p flag
allows measuring in telephoto mode, using instruments that support
this mode, e.g. the ColorMunki. Telephoto mode is one for taking
emissive measurements from a distance (ie. telespectometer,
tele-colorimeter) mode, and typically would be used for measuring
projector type displays. If a device does not support a specific
telephoto mode, then the normal emissive mode may be suitable for
The -y flag
allows setting the Display Type. The selection typically determines
two aspects of of the instrument operation: 1) It may set the measuring mode
to suite refresh or non-refresh displays.
Typically only LCD (Liquid Crystal) displays have a non-refresh
nature. 2) It may select an
instrument calibration matrix suitable for a particular display
type. The selections available depends on the type and model of
instrument, and a list of the options for the discovered instruments
will be shown in the usage
information. For more details on what particular instruments support
and how this works, see Operation of
particular instruments. 3) Any installed CCSS files
(if applicable), or CCMX files. These files are typically created
using ccxxmake, and installed using oeminst. The default and Base Calibration
types will be indicated in the usage.
default only the colorimetric information (XYZ value) will be saved,
but for instruments that support spectral readings (such as the
Gretag Spectrolino), the -s option will save the spectral
readings to the .ti3 file as well.
-k: If a
display video lookup table calibration .cal file is provided, it will
be loaded into the display VideoLUTs
while the measurements are being taken, thereby being applied to the
measurement values, and the calibration will also included in the
resulting .ti3 data file, so that colprof
can include it as a vcgt
tag in the resulting profile. This is the normal way to profile a calibrated display. The
calibration file has usually been created using dispcal. If the calibration file indicates
that the displays VideoLUTs are not accessible, or if they prove not
to be accessible, then dispread will switch to -K mode (see below). If a
calibration file is not supplied using -k or -K,
then the display will be measured in whatever calibration state it
is in, and no calibration information is saved to the resulting .ti3
If the calibration file provided created using video range encoding
(dispcal -E), then the -E option in dispread will be
NOTE that the calibration is
loaded into the display hardware just before the instrument starts
measurement, after the test window first appears.
-K: If a
display video lookup table calibration .cal file is provided, it will
be applied to the test values for each measurement, and also
included in the resulting .ti3 data file, so that colprof can include it as a vcgt tag in the resulting
profile. This is NOT
normally the best way to profile a calibrated display, since the
frame buffer may have lower precision than the VideoLUTs output
values. This is the way calibration should be applied if MadVR is
being used to display the test patches. If a calibration file is not
supplied using -k or -K, then the display will be
measured in whatever calibration state it is in, and no calibration
information is saved to the resulting .ti3 file.
If the calibration file provided created using video range encoding
(dispcal -E), then the -E option in dispread will be
-V: [MSWin] If using MadVR to display test
patches, then enable Color Managenent (3dLut). This would be used
for verification measurement.
parameter allows you to position and size the test patch window. By
default it is places in the center of the screen, and sized
appropriately for the type of instrument, or 10% of the width of the
display if the display size is unknown. The ho and vo values govern the horizontal
and vertical offset respectively. A value of 0.0 positions the
window to the far left or top of the screen, a value of 0.5
positions it in the center of the screen (the default), and 1.0
positions it to the far right or bottom of the screen. If three
parameters are provided, then the ss
parameter is a scale factor for the test window size. A value of 0.5
for instance, would produce a half sized window. A value of 2.0 will
produce a double size window. If four parameters are provided, then
the last two set independent horizontal and vertical scaling
factors. Note that the ho,vo,ss or ho,vo,hs,vs numbers must be
specified as a single string (no space between the numbers and the
comma). For example, to create a double sized test window at the top
right of the screen, use -P 1,0,2
. To create a window twice as wide as high: -P 1,0,2,1.
flag causes the while screen behind the test window to be masked
with black. This can aid black accuracy when measuring CRT displays
flag causes the test values to be scaled to the Video RGB encoding
range of 16/255 to 235/255. If the calibration file provided using
the -k or -K flag was created using video range
encoding, then this option will be triggered automatically. This
will also set quantization of 8 bits (see -Z flag below). If your
video connection is better than 8 bits (ie. 10 or 12 bits), then you
may wish to raise this default.
-Z nbits Normally the target device values
are floating point numbers that may get rounded and quantized in the
process of printing them or reproducing them on the display device.
If some of this quantization can be accounted for, it may improve
the accuracy of the resulting profile, and the Q parameter allows this
quantization to be specified. The parameter is the number of binary
digits (bits) that the device values should be quantized to. An idea
of the number of bits of precision that makes its way to your
display can be obtained by using dispcal
-R If Video encoding is selected (see -E flag above), then 8
bits is selected by default. On systems using an VGA connection or
Display Port with a graphics card with VideoLUT entries with greater
than 8 bits depth, or if using the MadVR rendered with dithering,
then a higher bit depth is typically possible.
running on a UNIX based system that used the X11 Windowing System, dispread
normally selects the override redirect so that the test window will
appear above any other windows on the display. On some systems this
can interfere with window manager operation, and the -n
option turns this behaviour off.
option runs through the black and sensor relative calibration
routines for the Xrite DTP92 and DTP94 instrument, the black level
calibration for the Eye-One Display 1, and a CRT frequency
calibration for the Eye-One Display 2. For the black calibration the
instrument should be placed on an opaque, black surface, and any
stray light should be avoided by placing something opaque over the
instrument. If a Spectrolino is being used, then a white and black
calibration will always be performed before the instrument can be
placed on the display, unless the -N flag is used.
Generally it is not necessary to do a calibration every time an
instrument is used, just now and again. There is no point in
doing a CRT frequency calibration, as this will be done
automatically at the commencement of patch reading.
instrument that requires regular calibration will ask for
calibration on initial start-up. Sometimes this can be awkward if
the instrument is being mounted in some sort of measuring jig, or
annoying if several sets of readings are being taken in quick
succession. The -N
suppresses this initial calibration if a valid and not timed out
previous calibration is recorded in the instrument or on the host
computer. It is advisable to only use this option on the second and
subsequent measurements in a single session.
option turns on high resolution spectral mode, if the instrument
supports it. See Operation of particular
instruments for more details. This may give better accuracy
for display measurements.
The -w flag disables the normalisation of
the white patch value to 100.0, resulting in values that are in
cd/m^2. This is mainly for diagnostic purposes.
The -X file.ccmx option reads
a Colorimeter Correction Matrix
from the given file, and applies it to the colorimeter instruments
readings. This can improve a colorimeters accuracy for a particular
type of display. A list of contributed ccmx files is here.
The -X file.ccss option reads
a Colorimeter Calibration
Spectral Sample from the given file, and uses it to set the
colorimeter instruments calibration. This will only work with
colorimeters that rely on sensor spectral sensitivity calibration
information (ie. the X-Rite i1d3,
or the DataColor Spyder4 &
Spyder 5).This can improve a colorimeters accuracy for a
particular type of display.
The -Q flag allows specifying a tristimulus
observer, and is used to compute PCS (Profile Connection Space)
tristimulus values from spectral readings or using a colorimeter
that has CCSS capability. The following choices are available:
1931_2 selects the standard CIE 1931 2 degree
observer. The default.
1964_10 selects the standard CIE 1964 10 degree
1955_2 selects the Stiles and Birch 1955 2 degree
1978_2 selects the Judd and Voss 1978 2 degree
shaw selects the Shaw and Fairchild 1997 2 degree
1964_10c selects a version of the CIE 1964 10 degree
observer that has been adjusted using a 3x3 matrix to better agree
with the 1931 2 degree observer.
NOTE that if you select
anything other than the default 1931 2 degree observer, that the Y
values will not be cd/m^2, due to the Y curve not being the CIE 1924
photopic V(λ) luminosity function.
The -I b|w options invoke
instrument black level, and display white level compensation
(respectively). Instrument black level drift compensation attempts
to combat instrument black calibration drift by using a display
black test patch as a reference. If an instrument is not
acclimatised sufficiently to the measurement conditions, changes in
temperature can affect the black readings. Display white level drift
compensation attempts to combat changes in display brightness as it
warms up by measuring a white patch every so often, and using it to
normalise all the other readings. If just instrument black drift
compensation is needed, use -Ib.
If just display white level compensation is needed, use -Iw. If both are needed, use -Ibw or -Iwb.
The -Y R:rate
options overrides calibration of the instrument refresh rate. This
may be useful if the instrument supports this function and the
refresh rate cannot be accurately calibrated from the display
The -Y A
option uses a non-adaptive integration time emission measurement
mode, if the instrument supports it, such as the Eye-One Pro,
ColorMunki, i1d3 and K10. By default an adaptive integration time
measurement mode will be used for emission measurements, but some
instruments support a fixed integration time mode that can be used
with display devices. This may give faster measurement times, but
may also give less accurate low level readings.
The -Y p
option skips asking the user to place the instrument on the display.
Normally a grey patch is displayed, and then the user is asked to
confirm that the instrument is in place, so that readings can
commence. This flag disables that check. This may be useful in
automating certain operations.
"command" option allows a
method of relaying each test value to some other display than that
on the system running dispread (for instance, a photo frame, PDA
screen etc.), by causing the given command to be invoked to the
shell, with six arguments. The first three arguments are the RGB
test color as integers in the range 0 to 255, the second three
parameters are the RGB test color as floating point numbers in the
range 0.0 to 1.0. The script or tool should relay the given color to
the screen in some manner (e.g. by generating a raster file of the
given color and sending it to the display being profiled), before
returning. Note that a test window will also be created on the
system running dispread.
The -M "command" option allows a
method of gathering each test value from some external source, such
as an instrument that is not directly supported by Argyll. The given
command is involked to the shell, with six arguments. The first
three arguments are the RGB test color as integers in the range 0 to
255, the second three parameters are the RGB test color as floating
point numbers in the range 0.0 to 1.0. The script or tool should
create a file called "command.meas"
that contains the XYZ values for the given RGB (or measured from the
test window) in cd/m^2 as three numbers separated by spaces, before
returning. If the command returns a non-zero return value, dispread
will abort. Note that a test window will also be created on the
system running dispread.
The -x flag causes dispread to expect
values to be manually entered for each reading, rather than using an
instrument to do the measurements. This mode is ideal if your
instrument is not supported by Argyll. XYZ values should be entered.
It is possible to navigate about the test values being measured, so
as to do them in any order, as well as re-do values, in case of any
The -W n|h|x
parameter overrides the default serial communications flow control
setting. The value n turns
all flow control off, h
sets hardware handshaking, and x
sets Xon/Xoff handshaking. This commend may be useful in workaround
serial communications issues with some systems and cables.
The -D flag causes communications and other
instrument diagnostics to be printed to stdout. A level can be set
between 1 .. 9, that may give progressively more verbose
information, depending on the instrument. This can be useful in
tracking down why an instrument can't connect.
The final parameter on the command line is the
base filename for the .ti1
input file, and the .ti3
output file. dispread will add the .ti1 and .ti3 extensions
NOTE that on an X11 system,
if the environment variable ARGYLL_IGNORE_XRANDR1_2
is set (ie. set it to "yes"), then the presence of the XRandR 1.2
extension will be ignored, and other extensions such as Xinerama and
XF86VidMode extension will be used. This may be a way to work around
buggy XRandR 1.2 implementations.
If a large number of patches is being read, the screensaver on many
systems can interfere with the operation of dispread. It is
therefore advisable in these cases to manually turn off the
screensaver before commencing the measurements.
If communications break down with a USB connected instrument, you
may have to unplug it, and plug it in again to recover.
Some systems (Apple OSX in particular) have a special set of user
interface controls ("Universal Access") that allows altering the
display in ways designed to assist visually impaired users, by
increasing contrast etc. This will interfere badly with any attempts
to calibrate or profile such a system, and must be turned off in
order to do so. Note that certain magic keyboard sequences can turn
this on by accident.