profile/printcal
    Summary
    Create a printer linearization calibration file from .ti3 test chart patch values.
    Usage Summary
     printcal [-options] [prevcal]
      inoutfile
       -v verbosity      
      Set verbosity level
     -p
                   
        Plot graphs.
       -i       
 
             Initial calibration, set targets,
      create .cal
     -r
                  
         Re-calibrate against previous .cal and create new
      .cal
     -e       
 
 
           Verify against previous .cal
     -I
                  
         Create imitation target from .ti3 and null
      calibration
     -d
                  
         Go through the motions but don't write any files
     -A "manufacturer"  Set the manufacturer
        description string
       -M "model"
                Set the model
        description string
       -D "description"   Set the profile
        Description string 
       -C "copyright"
            Set the copyright string
        -x# percent       
Set
initial
        maximum device % target (override auto)
       -m# percent       
          Set initial dev target to % of auto maximum
         -n# deltaE
                Set initial white
        minimum deltaE target
         -t# percent       
Set
initial
        50% transfer curve percentage target
           # = c, r,
          0      First channel
              
m,
g,
1     
          Second channel
              
y,
b,
2     
          Third channel
              
k,   
3     
Fourth
          channel, etc.
           -a                
Create
an
          Adobe Photoshop .AMP file as well as a .cal
         prevcal           
Base
name
          of previous .cal file for recal or verify.
         inoutname         
Base
name
          of input .ti3 file, output .cal file
      
    Options
    
    -v  Turn on verbose mode. Gives progress
    information as the calibration is created. An argument greater than
    1 increases the verbosity. Will also report the ideal power value to
    apply to the test chart in targen.
    
    -p Turns on
    plot mode. This causes various graphs to be plotted as the
    calibration is created. The channels will be plotted in the graph
    colors: Blue, Red, Yellow, Black, Green, Purple, Brown, Orange,
    Grey, White.
    
    -i Select
    initial calibration mode. Initial calibration mode allows setting
    the targets for the calibration, such as maximum device percentage,
    minimum white level, and the transfer curve shape. The second last
    parameter prevcal is not used in
    this mode.
    
    -r Turns on
    re-calibration mode. This is used for calibrations after the initial
    one, where the aim is to return the devices response to the same
    state as it was after the initial caibration. Parameters that affect
    the calibration targets are ignored. The second last parameter prevcal
    is used to establish what the targets for the calibration are.
    
    -e Turns on
    verify mode. In this mode the test chart input is verified agains
    the expected response in the prevcal file.
    
    -I Similar
    to -i, except that rather
    than creating a linear target curve and corresponding calibration,
    it takes the given behaviour as an absolute target and create a
    corresponding null set of calibration curves. This .cal can then be
    used to recalibrate a similar device (or the same device at some
    other time) to imitate the behaviour of the initial device. The
    second last parameter prevcal is not used in
    this mode. Parameters that affect the calibration targets are
    ignored.
    
    -d Disables
    the writing of any files, causing printcal to go through the motions
    without changing anything.
    
    The -A parameter allows setting of the
    device manufacturer description string in the calibration file. The
    parameter should be a string that identifies the manufacturer of the
    device being profiled. With most command line shells, it will be
    necessary to enclose the parameter with double quotes, so that
    spaces and other special characters are included in the parameter,
    and not mistaken for the start of another flag or as a final command
    line parameters. By default no device manufacturer description
    string will be put in the calibration file.
    
    The -M parameter allows setting of the
    device mode description string in the calibration file. The
    parameter should be a string that identifies the particular model of
    device being profiled. With most command line shells, it will be
    necessary to enclose the parameter with double quotes, so that
    spaces and other special characters are included in the parameter,
    and not mistaken for the start of another flag or as a final command
    line parameters. By default no model description string will be put
    in the calibration file.
    
    The -D parameter allows setting of the
    profile description string in the calibration file. The parameter
    should be a string that describes the device and profile. On many
    systems, it will be this string that will be used to identify the
    profile from a list of possible profiles. With most command line
    shells, it will be necessary to enclose the parameter with double
    quotes, so that spaces and other special characters are included in
    the parameter, and not mistaken for the start of another flag or as
    a final command line parameter. By default no profile description
    string will be put in the calibration file.
    
    The -C parameter allows setting of the
    profile copyright string in the calibration file. The parameter
    should be a string that describes the copyright (if any) claimed on
    the profile being generated. With most command line shells, it will
    be necessary to enclose the parameter with double quotes, so that
    spaces and other special characters are included in the parameter,
    and not mistaken for the start of another flag or as a final command
    line parameters. By default no copyright string will be put in the
    calibration file.
    
     The -x parameter allows overriding the
    default auto maximum device target value computed from the raw
    device response for the initial calibration. The default uses a
    heuristic to decide when the response of the device to each channels
    colorant value reaches the point of diminishing returns, while the -x parameter allows this default
    to be overridden. The -x
    paramater can be used multiple times, once for each channel that is
    being set. The -x should be
    followed by the channel number between 0 and 15, or the aliases r, g or g, or
    c, m, y or k, and
    the channel number should then be followed by the device value as a
    percentage. NOTE that you
    will probably get sub-optimal results if you force a device maximum
    that is beyond the point of maximum response of a device channel,
    since this will have the effect of reducing the device response. If you want to
    set a conservative target to allow for recalibration later, see the
    -m flag below.
    
     The -m parameter allows modifying the
    default auto maximum device target value for the initial
    calibration. The auto maximum is computed as described above, and is
    then scaled by the -m parameter value. Typically this will
    be a scale down (ie. 90%) to allow some margin to increase
    the channel value if the channel density drops in a future
    recalibration. Scaling the maximum down will reduce gamut, but
    allows scope for stable behaviour using calibration. The -m paramater can be used
    multiple times, once for each channel that is being set. The -m should be followed by the
    channel number between 0 and 15, or the aliases r, g or g, or
    c, m, y or k, and
    the channel number should then be followed by the deltaE value.
    
     The -n parameter allows overriding the
    default minimum deltaE of a colorant to white of 0. This can be used
    to set a minimum colorant level in order to emulate media darker or
    of a different tint. The -n
    paramater can be used multiple times, once for each channel that is
    being set. The -n should be
    followed by the channel number between 0 and 15, or the aliases r, g or g, or
    c, m, y or k, and
    the channel number should then be followed by the deltaE value.
    
     The -t parameter allows setting a target
    linearization curve that is other than purely visual linear. The
    default is to create a calibration curve that results in a perfectly
    even change in output for each change in the calibrated device
    value, as measured by steps in delta E94. The -x parameter allows setting a
    target curve above or below the perfectly visual linear, by setting
    the aim value at 50% input. An aim higher than 50% will cause that
    channel to become more intense by the 50% mark, while a value lower
    than 50% will cause the channel to become less intense by the 50%
    mark than perfectly linear.The -x
    should be followed by the channel number between 0 and 15, or the
    aliases r, g or g, or c, m, y or k, and
    the channel number should then be followed by the device value as a
    percentage.
    
    -a Creates
    an Adobe Photoshop .AMP
    format curves file as well as a .cal.
    
     The optional second last parameter is the file
    base name for a previous .cal
    calibration file, used as the target reference for recalibrate and
    verify modes. 
    
     The final parameter is the file base name for the
    .ti3 input test point data, and
    the resulting .cal calibration
    file output. 
    Discussion
    Printcal is a tool for
    creating per device channel linearization curves for printing
    devices.
    
    As input it takes a .ti3 file containing the results of printing a
    test chart on the non-color
      managed, non-calibrated
    device, and measuring it. The test chart consists of step wedges for
    each of the device primary colors, from the media white to full
    individual colorant intensity.
    
    For the initial calibration (-i),
the
range
    of device values to be used and the shape of the target
    linearization curve are established, as well as creating the first
    set of calibration curves. For subsequent re-calibrations (-r), the calibration curves aim
    to reproduce the same response as the original calibration. If a
    test chart is printed with calibration enabled and then is measured,
    it can be used to verify the calibration against the expected
    response (-e).
    
    As each colorant steps through the test wedge patches from media
    white, they trace out a measured locus in CIE L*a*b* colorspace.
    Each channel response is evaluated by computing the CIE DeltaE to
    media white of the response to a change in each individual channel
    of each locus. This measure is used to determine when the devices
    response to a colorant level is reaching diminishing returns,
    setting a maximum colorant value. This measure can also be used to
    set a minimum colorant value for the purposes of emulating a
    different media color. The default maximum and minimum values for
    each colorant can be overridden using the -x and -n
    parameters. The automatically determined maximum may be modified
    (scaled) using the -m parameter, which can be useful in
    allowing some margin for future calibrations to compensate for a
    drop in density.
    
    The actual linearization uses a subtly different measure, which is
    the CIE DelataE 94 along each colorant response locus, ensuring that
    after linearization each step in colorant value is subjectively
    even. The linearization aim can be altered from a purely linear
    curve by using the -t parameters.
    
    After the initial calibration, the device can be re-calibrated (-r) by printing a calibration
    test chart under the same conditions as the initial one, but with
    the calibration aimed at reproducing the same response as the
    initial calibration, rather that setting new targets.
    
    The calibration can be verified (-e)
    by printing a calibration test chart on non-color managed, but calibrated device,
    the verification evaluating any discrepancy between the device
    response achieved, and the device response expected. For a numerical
    evaluation the verbose flag (-v)
    should be used, and for a visual evaluation the plot flag (-p) should be used.
    
    If there are several devices of the same or similar model, then one
    device can be used to set the initial calibration target, and then
    the other devices can be re-calibrated against the same .cal file,
    to create matching responses. An alternative to creating an initial
    linear target for calibration, is to use the -I option with an initial
    device, which sets the initial target to be that devices absolute
    response. Naturally the corresponding calibration will be linear
    (null). The calibration target can then be used to later return that
    device to its initial response, or to make another similar device
    have the same response. Note though, that bad things will happen if
    the imitated devices response is non-monotonic, or if on
    re-calibration the device is unable to reach the same density
    levels.