spectro/printread

Summary

Read a printer test chart using an instrument, to create a .ti3 data file.

Usage

printread [-options] outfile
 -v                   Verbose mode
 -d                   Print debug diagnostics
 -c comport      Set COM port, 1..N (default 1)
 -i 41 | 51 | SS   Choose target instrument
                       41 = DTP41, 51 = DTP51, SS = Spectrolino or SpectroScan or SpectroScanT
 -t                    Use transmission measurement mode
-e                    Use emissive  measurement mode (absolute results)
-x [lx]              Take external values, either L*a*b* (-xl) or XYZ (-xx).
 -n                   Don't save spectral information (default saves spectral)
 inoutfile          Base name for input[.ti2]/output[.ti3] file

Usage Details

The -v flag causes extra information to be printed out during printread operation.

The -d flag causes serial communications diagnostics to be printed to stdout. This can be useful in tracking down why an instrument can't connect.

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 printread so as to display the usage information (i.e. "printread -?" or "printread --"), then the discovered serial ports will be listed on Windows and Mac OSX systems.

The type of instrument is normally specified when creating the test chart with printtarg, but it can be overridden by using the -i flag. Note that specifying -iSS will enable automatic detection of a Spectrlino (hand held), SpectroScan or SpectroScanT.

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 (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.

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.

The -x flag causes printread to expect values to be 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 mistakes.

By 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 flag.

The inoutfile parameters should be the base name of the .ti2 file, and printread will output an .ti3 that has the same basename and the .ti3 extension.

Discussion

When used with an Xrite DTP41 or DTP51 strip reading instrument, printread will first establish communications with the instrument, and then set it up ready to read the strips. The strips are labeled A to ZZ, and for each strip it will prompt:

    About to read strip XX  :

where XX is the strip label. You should line the appropriate strip up in the machine, and press its button. Since there is a slight delay between printing the "About to read" message and issuing the strip setup to the instrument, the button should be pressed a little after the message is displayed.

If the strip is read successfully, the line will be completed with:

    About to read strip  XX  :  Strip read OK

If there is an error of some sort, a message will be issued, and you will be asked whether to abort the chart reading, or retry the
failed strip:

    About to read strip X  : read_strip returned 'Strip misread' (Bad reading)

    Strip read failed due to misread
    Hit Esc to give up, any other key to retry:

If the strip is read successfully, but the patches values don't seem to be reasonable, you will get the following type of response:

    About to read strip  XX  :
    Seem to have read strip  YY  rather than  XX !
    Hit Return to use it anyway, any other key to retry:

If you are sure you lined up the correct strip, then hit return, otherwise line the appropriate strip up again, and hit some other key (ie. space).

You can abort the whole process at any time by hitting Escape.


When you are using an XY table type instrument, such as a Gretag SpectroScan,  printread will first establish communications with the instrument, and then set it up ready to read the chart. You will be prompted for each sheet with a message such as:

    Please make sure that the white reference is in slot 1, then
    place sheet 1 of 4 on table, then
    hit return to continue, Esc to give up

After hitting return you will be prompted to line up three squares on the sheet, one at a time:

    Using the XY table controls, locate patch A1 with the sight,
    then hit return to continue, Esc to give up

On completing this, the instrument will commence reading each sheet.