Read a printer test chart using an instrument, to create a .ti3 data file. The type of
instrument is determined by the communication port selected.
chartread can also be used
to read transmission values, and to read display values manually.
Set communication port from the following
list (default 1)
mode (white Y relative results)
Display type - instrument specific list to choose from.
mode (absolute results)
patch rather than strip
manually entered values, either L*a*b* (-xl) or XYZ (-xx).
save spectral information (default saves spectral)
Save CIE as D50 L*a*b* rather than XYZ
Save CIE as D50 L*a*b* as well as XYZ
calibration info from .ti2 in resulting .ti3
Set filter configuration:
XRGA conversion (default N)
Disable initial calibration of instrument unless
Disable auto bi-directional strip recognition
Use high resolution spectrum mode (if available)
Apply Colorimeter Correction Matrix
Choose CIE Observer for
spectral data or CCSS instrument:
1931_2 (def.), 1964_10, S&B 1955_2, shaw,
consistency tolerance by ratio (if available)
& unexpected value warnings
serial port flow control: n = none, h = HW, x = Xon/Xoff
diagnostics to stderr
Base name for input[.ti2]/output[.ti3] file
The -v flag causes extra information to be
printed out during chartread operation.
Normally instruments are connected via a serial
communication port, and the port used should be selected by
supplying the correct parameter to the -c flag. If you
invoke chartread so as to
display the usage information (i.e. "chartread -?" or "chartread
--"), then the discovered serial ports will be listed on Windows and
Mac OSX systems.
If using an Xrite DTP41T, and printing onto
transparent or back lit media, use the -t flag to operate
the instrument in transparency mode. If using a Spectrolino or
Eye-One Pro (handheld), this triggers a fake transparency mode, that
uses a separate backlight (such as a light box). The
instrument will be used to calibrate the level of backlight, and use
this to compute the transparency of the test chart samples. Note
that for good transparency values, the backlight level needs to be
neither too bright not too dark, should ideally be incandescent
rather than fluorescent (since fluorescent lights often have big
dips in their spectrum), and ideally should be of uniform brightness
over the measurement area. If using the SpectroScanT, the -t flag operates the instrument
in transparency mode, each reading being manually triggered.
The -d flag
allows measuring in display mode using instruments that support this
mode, with the brightness normalized to the white patch value in the
test chart. While the brightness values are then relative to the
white, the readings are otherwise absolute. This corresponds to the
raw ICC absolute readings created by dispread,
and is the mode that should be used for creating a normal display
ICC profile using manual, spot by spot readings. This can be useful
if the display cannot be driven directly by the computer, but can be
made manually to display the test charts.
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.
If using an instrument that supports an emissive
measurement mode (such as the Spectrolino), then the -e flag enables this measurement
mode, and the values recorded will be absolute XYZ values. This can
be used for media such as backlit film, measuring it on a lightbox,
so as to capture the actual illumination characteristics of that
particular media. An adaptive integration time will be used in
devices that support it.
flag causes chartread to use a spot read mode for an instrument,
even if it is capable of faster chart reading modes such as strip
reading. This can be useful if strip measurement patch recognition
is not reliable for certain media.
flag causes chartread 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. Either XYZ or L*a*b* values can be entered,
depending on what option follows -l, -lx to specify XYZ values, or -ll to specify L*a*b* values.
XYZ values are expected to be scaled to a maximum of 100. 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
default spectral information as well as D50 standard observer XYZ
values will be recorded for each test patch, when such readings are
available from a device. The spectral readings allow for choosing a
non-standard viewing illuminant, a non-standard observer model, or
the use of the Fluorescent Paper Whitener Additive compensation when
creating the profile. If the spectral readings are not needed, then
prinread operation can be speeded up by specifying the -n
default D50 standard observer XYZ values will be recorded for each
test patch, but if the -l flag is used, D50
L*a*b* values will be recorded instead.
default D50 standard observer XYZ values will be recorded for each
test patch, but if the -L flag is used, XYZ and D50 L*a*b* values will
default chartread reads the chart from scratch each time. When
reading a chart using a strip instrument or patch by patch you can
choose to finish chartread without reading all the patches, and
whatever patches have been read will be saved to the output .ti3
file. You can then resume
reading the patches by using the -r
flag, in which case chartread will read the .ti3 file and set the
patches to those previously read values, allowing any unread patches
to then be read, or to re-read previously read patches.
-I file.cal Normally per
channel calibration curves are added to the .ti2 file using the printtarg -K or -I options, so that they will be
passed on to the .ti3 file by chartread, so that colprof
is able to correctly compute total ink limits. Where the calibration
is being applied in a workflow with native calibration capability though, it is
sometimes convenient to re-use a profile chart with different
calibration curves without going through the process of using printtarg to re-create it. This
would mean though, that the calibration information and subsequent
ink limit calculations wouldn't be accurate. To overcome this and
allow such a scenario, the chartread
-I parameter allows overriding the .ti2 calibration curves
placed in the resulting .ti3 file with the actual calibration that
was used for that particular print.
The -F options allows configuring the
instrument to have a particular filter fitted to it. Some
instruments (i.e. the Gretag Spectrolino) allow the fitting of
various filters, such as a polarizing filter, D65 illuminant
simulation, or Ultra Violet Cut filter, and this option allows the
instrument to be configured appropriately.
The -A options allows overriding the default
or environment variable set XRGA
The N argument sets
the calibration to Native (default).
The A argument sets
the calibration to XRGA.
The X argument sets
the calibration to XRDI.
The G argument sets
the calibration to GMDI.
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.
strip instruments (i.e.. Eye-One Pro, Color Munki) when used with
Argyll will automatically recognize a strip when read in the reverse
direction by matching the patch readings against their expected
values. If the expected values are not known accurately enough, this
may cause erroneous reverse recognition, so the -B
flag allows this to be turned off, forcing strips to only be read in
the forward direction. (Note that the DTP20 always allows
bi-directional strip reading.) If the randomized patch layout has
not been used, then bi-directional strip recognition will
automatically turned off, and a warning issued if the -B flag is not
option turns on high resolution spectral mode, if the instrument
supports it. See Operation of particular
instruments for more details.
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 -T ratio
argument modifies the patch consistency tolerance threshold for some
strip reading instruments (ie. the Eye-One Pro). In recognizing
patches in a strip, an instrument may take multiple readings as the
strip is read, and then divide the readings up into each patch. It
may then check the consistency of the multiple readings
corresponding to each patch, and reject the measurement if they are
too inconsistent. For some media (ie. a coarser screens, fabric
etc.) the default tolerance may be unreasonably tight, so the -T ratio argument can be used to
modify this criteria. To loosen the tolerance, use a number greater
than 1.0 (ie. 1.5, 2.0).
The -Q flag allows specifying a tristimulus
observer for a colorimeter when using CCSS instrument calibration
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
The -S flag causes the normal "wrong strip"
and "unexpected value" warnings to be suppressed. There may be a lot
of these warnings if the expected patch value in the .ti2 file is in
fact far from the values actually being measured. It is probably
advisable to also use the -B
flag if warnings are turned off, since many warnings indicate that
the expected values are not to be relied on. With warnings
suppressed, greater care must be taken to read the correct strip. If
the randomized patch layout has not been used, then "wrong strip"
warnings will automatically be suppressed, and bi-directional strip
recognition turned off.
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 inoutfile parameters should be the
base name of the .ti2 file, and chartread will output an .ti3 that
has the same basename and the .ti3 extension. If the incoming .ti2
file contains per-channel calibration curves, these will be passed
through to the .ti3 so that accurate ink limits can be computed
For information about the operation of different instruments, see Operation of particular instruments.