1
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
1
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
4
<title>printcal</title>
5
<meta http-equiv="content-type"
6
content="text/html; charset=ISO-8859-1">
7
<meta name="author" content="Graeme W. Gill">
10
<h2> profile/printcal</h2>
12
Create a printer linearization calibration file from <a
13
href="File_Formats.html#.ti3">.ti3</a> test chart patch
15
<h3>Usage Summary</h3>
16
<span style="font-family: monospace;">printcal</span><small
17
style="font-family: monospace;"> [-<i>options</i>] [prevcal] inoutfile<br>
18
<a href="#v">-v verbosity</a> Set
20
</small><small style="font-family: monospace;"> <a href="#p">-p</a>
21
22
Plot graphs.<br>
23
<a href="#i">-i</a>
24
Initial calibration, set targets,
26
</small><small style="font-family: monospace;"> <a href="#r">-r</a>
27
28
Re-calibrate against previous .cal
30
create new .cal</small><br style="font-family: monospace;">
31
<span style="font-family: monospace;"></span><small
32
style="font-family: monospace;"> <a href="#e">-e</a>
34
Verify against previous .cal<br>
35
</small><small style="font-family: monospace;"> <a href="#I">-I</a>
36
37
Create imitation target from .ti3 and
38
null calibration</small><br>
39
<small style="font-family: monospace;"> <a href="#d">-d</a>
40
41
Go through the motions but don't
42
write any files</small><br style="font-family: monospace;">
43
<small><span style="font-family: monospace;"> </span><a
44
style="font-family: monospace;" href="#A">-A "manufacturer"</a><span
45
style="font-family: monospace;"> Set the manufacturer
46
description string</span><br style="font-family: monospace;">
47
<span style="font-family: monospace;"> </span><a
48
style="font-family: monospace;" href="#M">-M "model"</a><span
49
style="font-family: monospace;">
50
Set the model
51
description string</span><br style="font-family: monospace;">
52
<span style="font-family: monospace;"> </span><a
53
style="font-family: monospace;" href="#D">-D "description"</a><span
54
style="font-family: monospace;"> Set the
55
profile Description string </span><br style="font-family: monospace;">
56
<span style="font-family: monospace;"> </span><a
57
style="font-family: monospace;" href="#C">-C "copyright"</a><span
58
style="font-family: monospace;"><span style="font-family: monospace;">
59
Set the copyright
60
string</span><br style="font-family: monospace;">
61
<span style="font-family: monospace;"> </span><a
62
style="font-family: monospace;" href="#x">-x# percent</a><span
63
style="font-family: monospace;">
65
maximum device percentage target</span><br
66
style="font-family: monospace;">
67
<span style="font-family: monospace;"> </span><a
68
style="font-family: monospace;" href="#n">-n# deltaE</a><span
69
style="font-family: monospace;">
70
Set white minimum deltaE
71
target</span><br style="font-family: monospace;">
72
<span style="font-family: monospace;"> </span><a
73
style="font-family: monospace;" href="#t">-t# percent</a><span
74
style="font-family: monospace;">
76
50% transfer curve percentage target</span><br
77
style="font-family: monospace;">
78
<span style="font-family: monospace;"> # = c, r,
79
0 First channel</span><br
80
style="font-family: monospace;">
81
<span style="font-family: monospace;">
4
<title>printcal</title>
5
<meta http-equiv="content-type" content="text/html;
7
<meta name="author" content="Graeme W. Gill">
10
<h2> profile/printcal</h2>
12
Create a printer linearization calibration file from <a
13
href="File_Formats.html#.ti3">.ti3</a> test chart patch values.<br>
14
<h3>Usage Summary</h3>
15
<span style="font-family: monospace;">printcal</span><small
16
style="font-family: monospace;"> [-<i>options</i>] [prevcal]
18
<a href="#v">-v verbosity</a>
19
Set verbosity level<br>
20
</small><small style="font-family: monospace;"> <a href="#p">-p</a>
21
22
Plot graphs.<br>
23
<a href="#i">-i</a>
26
Initial calibration, set targets,
28
</small><small style="font-family: monospace;"> <a href="#r">-r</a>
29
30
Re-calibrate against previous .cal and create new
31
.cal</small><br style="font-family: monospace;">
32
<span style="font-family: monospace;"></span><small
33
style="font-family: monospace;"> <a href="#e">-e</a>
37
Verify against previous .cal<br>
38
</small><small style="font-family: monospace;"> <a href="#I">-I</a>
39
40
Create imitation target from .ti3 and null
41
calibration</small><br>
42
<small style="font-family: monospace;"> <a href="#d">-d</a>
43
44
Go through the motions but don't write any files</small><br
45
style="font-family: monospace;">
46
<small><span style="font-family: monospace;"> </span><a
47
style="font-family: monospace;" href="#A">-A "manufacturer"</a><span
48
style="font-family: monospace;"> Set the manufacturer
49
description string</span><br style="font-family: monospace;">
50
<span style="font-family: monospace;"> </span><a
51
style="font-family: monospace;" href="#M">-M "model"</a><span
52
style="font-family: monospace;">
53
Set the model
54
description string</span><br style="font-family: monospace;">
55
<span style="font-family: monospace;"> </span><a
56
style="font-family: monospace;" href="#D">-D "description"</a><span
57
style="font-family: monospace;"> Set the profile
58
Description string </span><br style="font-family: monospace;">
59
<tt> </tt><tt><a href="#C">-C "copyright"</a></tt><tt>
60
Set the copyright string</tt><tt><br>
61
</tt><tt> </tt><tt> </tt><tt><a href="#x">-x# percent</a></tt><tt>
65
maximum device % target (override auto)</tt><tt><br>
66
</tt></small><small><span style="font-family: monospace;"><small> <a
67
href="#m">-m# percent</a>
69
Set initial dev target to % of auto maximum<br>
70
</small> <a href="#n">-n# deltaE</a>
71
Set initial white
72
minimum deltaE target<br>
73
<a href="#t">-t# percent</a>
77
50% transfer curve percentage target<br style="font-family:
79
<span style="font-family: monospace;"> # = c, r,
80
0 First channel</span><br
81
style="font-family: monospace;">
82
<span style="font-family: monospace;">
84
1 Second channel</span><br
85
style="font-family: monospace;">
86
<span style="font-family: monospace;">
85
1
87
Second channel</span><br style="font-family: monospace;">
88
<span style="font-family: monospace;">
89
2 Third channel</span><br
90
style="font-family: monospace;">
91
<span style="font-family: monospace;">
91
2
93
Third channel</span><br style="font-family: monospace;">
94
<span style="font-family: monospace;">
92
95
k,
93
96
3
94
Fourth channel, etc.<br>
95
<a href="#a">-a</a>
100
<a href="#a">-a</a>
97
an Adobe Photoshop .AMP file as well as a .cal<br
98
style="font-family: monospace;">
99
</span><span style="font-family: monospace;"> </span><a
100
style="font-family: monospace;" href="#p1">prevcal</a><span
101
style="font-family: monospace;">
103
name of previous .cal file for recal or verify.</span><br
104
style="font-family: monospace;">
105
<span style="font-family: monospace;"> </span><a
106
style="font-family: monospace;" href="#p2">inoutname</a><span
107
style="font-family: monospace;">
109
name of input .ti3 file, output .cal file</span><br>
110
</span><span style="font-family: monospace;"></span></small><small><span
111
style="font-family: monospace;"></span><span
112
style="font-family: monospace;"></span><span
113
style="font-family: monospace;"></span></small><br>
116
<b><a name="v"></a>-v</b> Turn on verbose mode. Gives progress
117
information as the calibration is created. An argument greater than 1
118
increases the verbosity. Will also report the ideal power value to
119
apply to the test chart in targen.<br>
121
<a name="p"></a><span style="font-weight: bold;">-p</span> Turns on
122
plot mode. This causes various graphs to be plotted as the calibration
123
is created. The channels will be plotted in the graph colors: Blue,
124
Red, Yellow, Black, Green, Purple, Brown, Orange, Grey, White.<br>
126
<a name="i"></a><span style="font-weight: bold;">-i</span> Select
127
initial calibration mode. Initial calibration mode allows setting the
128
targets for the calibration, such as maximum device percentage, minimum
129
white level, and the transfer curve shape. The second last parameter <span
130
style="font-weight: bold;"><span style="font-weight: bold;"></span>prevcal</span>
131
is not used in this mode.<br>
133
<a name="r"></a><span style="font-weight: bold;">-r</span> Turns on
134
re-calibration mode. This is used for calibrations after the initial
135
one, where the aim is to return the devices response to the same state
136
as it was after the initial caibration. Parameters that affect the
137
calibration targets are ignored. The second last parameter <span
138
style="font-weight: bold;"><span style="font-weight: bold;"></span>prevcal</span>
139
is used to establish what the targets for the calibration are.<br>
141
<a name="e"></a><span style="font-weight: bold;">-e</span> Turns on
142
verify mode. In this mode the test chart input is verified agains the
143
expected response in the <span style="font-weight: bold;"><span
144
style="font-weight: bold;"></span>prevcal</span> file.<br>
146
<a name="I"></a><span style="font-weight: bold;">-I</span> Similar to <span
147
style="font-weight: bold;">-i</span>, except that rather than creating
148
a linear target curve and corresponding calibration, it takes the given
149
behaviour as an absolute target and create a corresponding null set of
150
calibration curves. This .cal can then be used to recalibrate a similar
151
device (or the same device at some other time) to imitate the behaviour
152
of the initial device. The second last parameter <span
153
style="font-weight: bold;"><span style="font-weight: bold;"></span>prevcal</span>
154
is not used in this mode. Parameters that affect the
155
calibration targets are ignored.<br>
157
<a name="d"></a><span style="font-weight: bold;">-d</span> Disables the
158
writing of any files, causing printcal to go through the motions
159
without changing anything.<br>
161
<a name="A"></a>The <b>-A</b> parameter allows setting of the device
162
manufacturer description string in the calibration file. The parameter
163
should be a string that
164
identifies the manufacturer of the device being profiled. With most
165
command line shells, it will be necessary to enclose the parameter
166
with double quotes, so that spaces and other special characters are
167
included in the parameter, and not mistaken for the start of another
168
flag or as a final command line parameters. By default no device
169
manufacturer description string
170
will be put in the calibration file.<br>
172
<a name="M"></a>The <b>-M</b> parameter allows setting of the device
173
mode description string in the calibration file. The parameter should
174
be a string that identifies
175
the particular model of device being profiled. With most command line
176
shells, it will be necessary to enclose the parameter with double
177
quotes, so that spaces and other special characters are included in the
178
parameter, and not mistaken for the start of another flag or as a
179
final command line parameters. By default no model description string
180
will be put in the calibration file.<br>
182
<a name="D"></a>The <b>-D</b> parameter allows setting of the profile
183
description string in the calibration file. The parameter should be a
184
string that describes the
185
device and profile. On many systems, it will be this string that will
186
be used to identify the profile from a list of possible profiles. With
187
most command line shells, it will be
188
necessary to enclose the parameter with double quotes, so that spaces
189
and other special characters are included in the parameter, and not
190
mistaken for the start of another flag or as a final command line
191
parameter. By default no profile description string
192
will be put in the calibration file.<br>
194
<a name="C"></a>The <b>-C</b> parameter allows setting of the profile
195
copyright string in the calibration file. The parameter should be a
196
string that describes the
197
copyright (if any) claimed on the profile being generated. With most
198
command line shells, it will be necessary to enclose the parameter
199
with double quotes, so that spaces and other special characters are
200
included in the parameter, and not mistaken for the start of another
201
flag or as a final command line parameters. By default no copyright
203
will be put in the calibration file.<br>
205
<a name="x"></a> The <b>-x</b> parameter allows overriding the default
206
maximum device value computed from the raw device response. The default
207
uses a heuristic to decide when the response of the device to each
208
channels colorant value reaches the point of diminishing returns, while
209
the <span style="font-weight: bold;">-x</span> parameter allows this
210
default to be overridden. The <span style="font-weight: bold;">-x</span>
211
paramater can be used multiple times, once for each channel that is
212
being set. The <span style="font-weight: bold;">-x</span> should be
213
followed by the channel number between 0 and 15, or the aliases <span
214
style="font-weight: bold;">r</span>, <span style="font-weight: bold;">g</span>
215
or <span style="font-weight: bold;">g</span>, or <span
216
style="font-weight: bold;">c</span>, <span style="font-weight: bold;">m</span>,
217
<span style="font-weight: bold;">y</span> or <span
218
style="font-weight: bold;">k,</span> and the channel number should
219
then be followed by the device value as a percentage. <span
220
style="font-weight: bold;">NOTE</span> that you will probably get
221
sub-optimal results if you force a device maximum that is beyond the
222
point of maximum response of a device channel, since this will have the
223
effect of <span style="text-decoration: underline;">reducing</span>
224
the device response.<br>
226
<a name="n"></a> The <b>-n</b> parameter allows overriding the default
227
minimum deltaE of a colorant to white of 0. This can be used to set
228
a minimum colorant level in order to emulate media darker or of a
229
different tint. The <span style="font-weight: bold;">-n</span>
230
paramater can be used multiple times, once for each channel that is
231
being set. The <span style="font-weight: bold;">-n</span> should be
232
followed by the channel number between 0 and 15, or the aliases <span
233
style="font-weight: bold;">r</span>, <span style="font-weight: bold;">g</span>
234
or <span style="font-weight: bold;">g</span>, or <span
235
style="font-weight: bold;">c</span>, <span style="font-weight: bold;">m</span>,
236
<span style="font-weight: bold;">y</span> or <span
237
style="font-weight: bold;">k,</span> and the channel number should
238
then be followed by the deltaE value.<span
239
style="font-family: monospace;"></span><br>
241
<a name="t"></a> The <b>-t</b> parameter allows setting a target
242
linearization curve that is other than purely linear. The default
243
is to create a calibration curve that results in a perfectly even
244
change in output for each change in the calibrated device value, as
245
measured by steps in delta E94. The <span style="font-weight: bold;">-x</span>
246
parameter allows setting a target curve above or belowe the perfectly
247
linear, by setting the aim value at 50% input. An aim higher than 50%
248
will cause that channel to become more intense by the 50% mark, while a
249
value lower than 50% will cause the channel to become less intense by
250
the 50% mark than perfectly linear.The <span style="font-weight: bold;">-x</span>
251
should be followed by the channel number between 0 and 15, or the
252
aliases <span style="font-weight: bold;">r</span>, <span
253
style="font-weight: bold;">g</span> or <span
254
style="font-weight: bold;">g</span>, or <span
255
style="font-weight: bold;">c</span>, <span style="font-weight: bold;">m</span>,
256
<span style="font-weight: bold;">y</span> or <span
257
style="font-weight: bold;">k,</span> and the channel number should
258
then be followed by the device value as a percentage.<br>
260
<a name="a"></a><span style="font-weight: bold;">-a</span> Creates an
261
Adobe Photoshop <span style="font-weight: bold;">.AMP</span> format
262
curves file as well as a .cal.<br>
263
<span style="font-weight: bold;"></span><br>
264
<a name="p1"></a> The optional second last parameter is the file base
265
name for a previous <a href="File_Formats.html#CAL">.cal</a>
266
calibration file, used as the target reference for recalibrate and
269
<a name="p2"></a> The final parameter is the file base name for the <a
270
href="File_Formats.html#.ti3">.ti3</a> input test point data, and the
271
resulting <a href="File_Formats.html#CAL">.cal</a> calibration file
273
<h3><a name="DISCUSSION"></a>Discussion</h3>
274
<span style="font-weight: bold;">Printcal</span> is a tool for creating
275
per device channel linearization curves for printing devices.<br>
277
As input it takes a .ti3 file containing the results of printing a test
278
chart on the <span style="text-decoration: underline;">non-color
279
managed</span>, <span style="text-decoration: underline;">non-calibrated</span>
280
device, and measuring it. The test chart consists of step wedges for
281
each of the device primary colors, from the media white to full
282
individual colorant intensity.<br>
284
For the initial calibration (<span style="font-weight: bold;">-i</span>),
104
Adobe Photoshop .AMP file as well as a .cal<br
105
style="font-family: monospace;">
106
</span><span style="font-family: monospace;"> </span><a
107
style="font-family: monospace;" href="#p1">prevcal</a><span
108
style="font-family: monospace;">
112
of previous .cal file for recal or verify.</span><br
113
style="font-family: monospace;">
114
<span style="font-family: monospace;"> </span><a
115
style="font-family: monospace;" href="#p2">inoutname</a><span
116
style="font-family: monospace;">
120
of input .ti3 file, output .cal file</span><br>
121
</span><span style="font-family: monospace;"></span></small><small><span
122
style="font-family: monospace;"></span><span style="font-family:
123
monospace;"></span><span style="font-family: monospace;"></span></small><br>
126
<b><a name="v"></a>-v</b> Turn on verbose mode. Gives progress
127
information as the calibration is created. An argument greater than
128
1 increases the verbosity. Will also report the ideal power value to
129
apply to the test chart in targen.<br>
131
<a name="p"></a><span style="font-weight: bold;">-p</span> Turns on
132
plot mode. This causes various graphs to be plotted as the
133
calibration is created. The channels will be plotted in the graph
134
colors: Blue, Red, Yellow, Black, Green, Purple, Brown, Orange,
137
<a name="i"></a><span style="font-weight: bold;">-i</span> Select
138
initial calibration mode. Initial calibration mode allows setting
139
the targets for the calibration, such as maximum device percentage,
140
minimum white level, and the transfer curve shape. The second last
141
parameter <span style="font-weight: bold;"><span
142
style="font-weight: bold;"></span>prevcal</span> is not used in
145
<a name="r"></a><span style="font-weight: bold;">-r</span> Turns on
146
re-calibration mode. This is used for calibrations after the initial
147
one, where the aim is to return the devices response to the same
148
state as it was after the initial caibration. Parameters that affect
149
the calibration targets are ignored. The second last parameter <span
150
style="font-weight: bold;"><span style="font-weight: bold;"></span>prevcal</span>
151
is used to establish what the targets for the calibration are.<br>
153
<a name="e"></a><span style="font-weight: bold;">-e</span> Turns on
154
verify mode. In this mode the test chart input is verified agains
155
the expected response in the <span style="font-weight: bold;"><span
156
style="font-weight: bold;"></span>prevcal</span> file.<br>
158
<a name="I"></a><span style="font-weight: bold;">-I</span> Similar
159
to <span style="font-weight: bold;">-i</span>, except that rather
160
than creating a linear target curve and corresponding calibration,
161
it takes the given behaviour as an absolute target and create a
162
corresponding null set of calibration curves. This .cal can then be
163
used to recalibrate a similar device (or the same device at some
164
other time) to imitate the behaviour of the initial device. The
165
second last parameter <span style="font-weight: bold;"><span
166
style="font-weight: bold;"></span>prevcal</span> is not used in
167
this mode. Parameters that affect the calibration targets are
170
<a name="d"></a><span style="font-weight: bold;">-d</span> Disables
171
the writing of any files, causing printcal to go through the motions
172
without changing anything.<br>
174
<a name="A"></a>The <b>-A</b> parameter allows setting of the
175
device manufacturer description string in the calibration file. The
176
parameter should be a string that identifies the manufacturer of the
177
device being profiled. With most command line shells, it will be
178
necessary to enclose the parameter with double quotes, so that
179
spaces and other special characters are included in the parameter,
180
and not mistaken for the start of another flag or as a final command
181
line parameters. By default no device manufacturer description
182
string will be put in the calibration file.<br>
184
<a name="M"></a>The <b>-M</b> parameter allows setting of the
185
device mode description string in the calibration file. The
186
parameter should be a string that identifies the particular model of
187
device being profiled. With most command line shells, it will be
188
necessary to enclose the parameter with double quotes, so that
189
spaces and other special characters are included in the parameter,
190
and not mistaken for the start of another flag or as a final command
191
line parameters. By default no model description string will be put
192
in the calibration file.<br>
194
<a name="D"></a>The <b>-D</b> parameter allows setting of the
195
profile description string in the calibration file. The parameter
196
should be a string that describes the device and profile. On many
197
systems, it will be this string that will be used to identify the
198
profile from a list of possible profiles. With most command line
199
shells, it will be necessary to enclose the parameter with double
200
quotes, so that spaces and other special characters are included in
201
the parameter, and not mistaken for the start of another flag or as
202
a final command line parameter. By default no profile description
203
string will be put in the calibration file.<br>
205
<a name="C"></a>The <b>-C</b> parameter allows setting of the
206
profile copyright string in the calibration file. The parameter
207
should be a string that describes the copyright (if any) claimed on
208
the profile being generated. With most command line shells, it will
209
be necessary to enclose the parameter with double quotes, so that
210
spaces and other special characters are included in the parameter,
211
and not mistaken for the start of another flag or as a final command
212
line parameters. By default no copyright string will be put in the
213
calibration file.<br>
215
<a name="x"></a> The <b>-x</b> parameter allows overriding the
216
default auto maximum device target value computed from the raw
217
device response for the initial calibration. The default uses a
218
heuristic to decide when the response of the device to each channels
219
colorant value reaches the point of diminishing returns, while the <span
220
style="font-weight: bold;">-x</span> parameter allows this default
221
to be overridden. The <span style="font-weight: bold;">-x</span>
222
paramater can be used multiple times, once for each channel that is
223
being set. The <span style="font-weight: bold;">-x</span> should be
224
followed by the channel number between 0 and 15, or the aliases <span
225
style="font-weight: bold;">r</span>, <span style="font-weight:
226
bold;">g</span> or <span style="font-weight: bold;">g</span>, or
227
<span style="font-weight: bold;">c</span>, <span
228
style="font-weight: bold;">m</span>, <span style="font-weight:
229
bold;">y</span> or <span style="font-weight: bold;">k,</span> and
230
the channel number should then be followed by the device value as a
231
percentage. <span style="font-weight: bold;">NOTE</span> that you
232
will probably get sub-optimal results if you force a device maximum
233
that is beyond the point of maximum response of a device channel,
234
since this will have the effect of <span style="text-decoration:
235
underline;">reducing</span> the device response. If you want to
236
set a conservative target to allow for recalibration later, see the
237
<b>-m</b> flag below.<br>
239
<a name="m"></a> The <b>-m</b> parameter allows modifying the
240
default auto maximum device target value for the initial
241
calibration. The auto maximum is computed as described above, and is
242
then scaled by the <b>-m</b> parameter value. Typically this will
243
be a scale down (ie. <b>90%</b>) to allow some margin to increase
244
the channel value if the channel density drops in a future
245
recalibration. Scaling the maximum down will reduce gamut, but
246
allows scope for stable behaviour using calibration. The <span
247
style="font-weight: bold;">-m</span> paramater can be used
248
multiple times, once for each channel that is being set. The <span
249
style="font-weight: bold;">-m</span> should be followed by the
250
channel number between 0 and 15, or the aliases <span
251
style="font-weight: bold;">r</span>, <span style="font-weight:
252
bold;">g</span> or <span style="font-weight: bold;">g</span>, or
253
<span style="font-weight: bold;">c</span>, <span
254
style="font-weight: bold;">m</span>, <span style="font-weight:
255
bold;">y</span> or <span style="font-weight: bold;">k,</span> and
256
the channel number should then be followed by the deltaE value.<span
257
style="font-family: monospace;"></span><br>
259
<a name="n"></a> The <b>-n</b> parameter allows overriding the
260
default minimum deltaE of a colorant to white of 0. This can be used
261
to set a minimum colorant level in order to emulate media darker or
262
of a different tint. The <span style="font-weight: bold;">-n</span>
263
paramater can be used multiple times, once for each channel that is
264
being set. The <span style="font-weight: bold;">-n</span> should be
265
followed by the channel number between 0 and 15, or the aliases <span
266
style="font-weight: bold;">r</span>, <span style="font-weight:
267
bold;">g</span> or <span style="font-weight: bold;">g</span>, or
268
<span style="font-weight: bold;">c</span>, <span
269
style="font-weight: bold;">m</span>, <span style="font-weight:
270
bold;">y</span> or <span style="font-weight: bold;">k,</span> and
271
the channel number should then be followed by the deltaE value.<span
272
style="font-family: monospace;"></span><br>
274
<a name="t"></a> The <b>-t</b> parameter allows setting a target
275
linearization curve that is other than purely visual linear. The
276
default is to create a calibration curve that results in a perfectly
277
even change in output for each change in the calibrated device
278
value, as measured by steps in delta E94. The <span
279
style="font-weight: bold;">-x</span> parameter allows setting a
280
target curve above or below the perfectly visual linear, by setting
281
the aim value at 50% input. An aim higher than 50% will cause that
282
channel to become more intense by the 50% mark, while a value lower
283
than 50% will cause the channel to become less intense by the 50%
284
mark than perfectly linear.The <span style="font-weight: bold;">-x</span>
285
should be followed by the channel number between 0 and 15, or the
286
aliases <span style="font-weight: bold;">r</span>, <span
287
style="font-weight: bold;">g</span> or <span style="font-weight:
288
bold;">g</span>, or <span style="font-weight: bold;">c</span>, <span
289
style="font-weight: bold;">m</span>, <span style="font-weight:
290
bold;">y</span> or <span style="font-weight: bold;">k,</span> and
291
the channel number should then be followed by the device value as a
294
<a name="a"></a><span style="font-weight: bold;">-a</span> Creates
295
an Adobe Photoshop <span style="font-weight: bold;">.AMP</span>
296
format curves file as well as a .cal.<br>
297
<span style="font-weight: bold;"></span><br>
298
<a name="p1"></a> The optional second last parameter is the file
299
base name for a previous <a href="File_Formats.html#CAL">.cal</a>
300
calibration file, used as the target reference for recalibrate and
303
<a name="p2"></a> The final parameter is the file base name for the
304
<a href="File_Formats.html#.ti3">.ti3</a> input test point data, and
305
the resulting <a href="File_Formats.html#CAL">.cal</a> calibration
307
<h3><a name="DISCUSSION"></a>Discussion</h3>
308
<span style="font-weight: bold;">Printcal</span> is a tool for
309
creating per device channel linearization curves for printing
312
As input it takes a .ti3 file containing the results of printing a
313
test chart on the <span style="text-decoration: underline;">non-color
315
managed</span>, <span style="text-decoration: underline;">non-calibrated</span>
316
device, and measuring it. The test chart consists of step wedges for
317
each of the device primary colors, from the media white to full
318
individual colorant intensity.<br>
320
For the initial calibration (<span style="font-weight: bold;">-i</span>),
286
range of device values to be used and the shape of the target
287
linearization curve are established, as well as creating the first set
288
of calibration curves. For subsequent re-calibrations (<span
289
style="font-weight: bold;">-r</span>), the calibration curves aim to
290
reproduce the same response as the original calibration. If a test
291
chart is printed with calibration enabled and then is mesured, it can
293
verify the calibration against the expected response (<span
294
style="font-weight: bold;">-e</span>).<br>
296
As each colorant steps through the test wedge patches from media white,
297
they trace out a measured locus in CIE L*a*b* colorspace. Each channel
298
response is evaluated by computing the CIE DeltaE to media white of
299
the response to a change in each individual channel of each locus. This
300
measure is used to determine when the devices response to a colorant
301
level is reaching diminishing returns, setting a maximum colorant
302
value. This measure can also be used to set a minimum colorant value
303
for the purposes of emulating a different media color. The default
304
maximum and minum values for each colorant can be overriden using the <span
305
style="font-weight: bold;">-x</span> and <span
306
style="font-weight: bold;">-n</span> parameters.<br>
308
The actual linearization uses a subtly different measure, which is the
309
CIE DelataE 94 along each colorant response locus, ensuring that after
310
linearization each step in colorant value is subjectively even. The
311
linearization aim can be altered from a purely linear curve by using
312
the <span style="font-weight: bold;"><span style="font-weight: bold;">-t</span></span>
315
After the initial calibration, the device can be re-calibrated (<span
316
style="font-weight: bold;">-r</span>) by printing a calibration test
317
chart under the same conditions as the initial one, but with the
318
calibration aimed at reproducing the same response as the initial
319
calibration, rather that setting new targets.<br>
321
The calibration can be verified (<span style="font-weight: bold;">-e</span>)
323
printing a calibration test chart on <span
324
style="text-decoration: underline;">non-color managed</span>, <span
325
style="text-decoration: underline;"></span>but calibrated device, the
326
verification evaluating any discrepancy between the device response
327
acheived, and the device response expected. For a numerical evaluation
328
the verbose flag (<span style="font-weight: bold;">-v</span>) should be
329
used, and for a visual evaluation the plot flag (<span
330
style="font-weight: bold;">-p</span>) should be used.<br>
332
If there are several devices of the same or similar model, then one
333
device can be used to set the initial calibration target, and then the
334
other devices can be re-calibrated against the same .cal file, to
335
create matching responses. An alternative to creating an initial linear
336
target for calibration, is to use the <span style="font-weight: bold;">-I</span>
337
option with an initial device, which sets the initial target to be that
338
devices absolute response. Naturally the corresponding calibration will
339
be linear (null). The calibration target can then be used to later
340
return that device to its initial response, or to make another similar
341
device have the same response. Note though, that bad things will happen
342
if the imitated devices response is non-monotonic, or if on
343
re-calibration the device is unable to reach the same density levels.<br>
324
of device values to be used and the shape of the target
325
linearization curve are established, as well as creating the first
326
set of calibration curves. For subsequent re-calibrations (<span
327
style="font-weight: bold;">-r</span>), the calibration curves aim
328
to reproduce the same response as the original calibration. If a
329
test chart is printed with calibration enabled and then is measured,
330
it can be used to verify the calibration against the expected
331
response (<span style="font-weight: bold;">-e</span>).<br>
333
As each colorant steps through the test wedge patches from media
334
white, they trace out a measured locus in CIE L*a*b* colorspace.
335
Each channel response is evaluated by computing the CIE DeltaE to
336
media white of the response to a change in each individual channel
337
of each locus. This measure is used to determine when the devices
338
response to a colorant level is reaching diminishing returns,
339
setting a maximum colorant value. This measure can also be used to
340
set a minimum colorant value for the purposes of emulating a
341
different media color. The default maximum and minimum values for
342
each colorant can be overridden using the <span style="font-weight:
343
bold;">-x</span> and <span style="font-weight: bold;">-n</span>
344
parameters. The automatically determined maximum may be modified
345
(scaled) using the <b>-m</b> parameter, which can be useful in
346
allowing some margin for future calibrations to compensate for a
349
The actual linearization uses a subtly different measure, which is
350
the CIE DelataE 94 along each colorant response locus, ensuring that
351
after linearization each step in colorant value is subjectively
352
even. The linearization aim can be altered from a purely linear
353
curve by using the <span style="font-weight: bold;"><span
354
style="font-weight: bold;">-t</span></span> parameters.<br>
356
After the initial calibration, the device can be re-calibrated (<span
357
style="font-weight: bold;">-r</span>) by printing a calibration
358
test chart under the same conditions as the initial one, but with
359
the calibration aimed at reproducing the same response as the
360
initial calibration, rather that setting new targets.<br>
362
The calibration can be verified (<span style="font-weight: bold;">-e</span>)
363
by printing a calibration test chart on <span
364
style="text-decoration: underline;">non-color managed</span>, <span
365
style="text-decoration: underline;"></span>but calibrated device,
366
the verification evaluating any discrepancy between the device
367
response achieved, and the device response expected. For a numerical
368
evaluation the verbose flag (<span style="font-weight: bold;">-v</span>)
369
should be used, and for a visual evaluation the plot flag (<span
370
style="font-weight: bold;">-p</span>) should be used.<br>
372
If there are several devices of the same or similar model, then one
373
device can be used to set the initial calibration target, and then
374
the other devices can be re-calibrated against the same .cal file,
375
to create matching responses. An alternative to creating an initial
376
linear target for calibration, is to use the <span
377
style="font-weight: bold;">-I</span> option with an initial
378
device, which sets the initial target to be that devices absolute
379
response. Naturally the corresponding calibration will be linear
380
(null). The calibration target can then be used to later return that
381
device to its initial response, or to make another similar device
382
have the same response. Note though, that bad things will happen if
383
the imitated devices response is non-monotonic, or if on
384
re-calibration the device is unable to reach the same density
added
removed
doc/printcal.html
