10.5 Calibrating Your Color Monitor
The Kodak Color Management System (KCMS) with Solaris 2.5, helps you maintain accurate color as your images are scanned, viewed on a monitor, printed, recorded on film, or otherwise reproduced.
In this section, the following information is provided:
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General concepts of monitor calibration
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How to adjust your viewing environment
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How to connect the Calibrator Tool hardware or puck
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How to run Calibrator Tool
Note -The puck is not mandatory, but it is highly recommended that you use it to calibrate your color monitor. If you do not have a puck you can still calibrate your monitor.
10.5.1 Monitor Calibration Concepts
Every color device, such as a scanner, monitor or printer, has a set of color reproduction characteristics. The KCMS software uses a set of characterization data for a particular make and model of a color device. Gathering characterization data of a scanner or a monitor requires highly specialized instruments and is called characterization. Characterization results in a file called a nominal profile that contains detailed, machine-readable color reproduction information. A collection of nominal profiles are provided with the KCMS product. Nominal is an average color response derived from measurements taken from several samples of each type of device.
Note -
Currently only monitors can be characterized; scanners and printers cannot be characterized.
The nominal profile represents the color reproduction of a device at known settings and in a known environment. Nominal profiles are adequate for most workstation users. But the reproduction characteristics of a color device change due to age, media, and temperature. To obtain accurate color reproduction, you should adjust the nominal profile to reflect the actual reproduction characteristics of your device in your viewing environment. The process of adjusting the nominal profile is called calibration. For more information on adjusting your viewing environment, see "10.5.2 Adjusting Your Viewing Environment". For more information on calibrated profiles, see "10.5.1.1 Calibrated Profiles and Visuals".
Although scanner and printer calibration is difficult, video monitor calibration is accomplished by displaying a programmed sequence of test colors and measuring the output of the display by a puck. The KCMS library then computes the correction factors necessary to compensate for the inaccuracies of the monitor. This process is monitor calibration. The KCMS Calibrator Tool performs monitor calibration. See "10.5.4 Running Calibrator Tool"for instructions on how to calibrate your monitor with Calibrator Tool.
If you adjust any of your monitor's front-panel controls (such as Brightness, Contrast, Picture or Black Level) you need to recalibrate to update the color reproduction of your monitor. If you are a critical user of color, you should recalibrate whenever you adjust any of these settings or once every two weeks. You must recalibrate if you replace your monitor or your framebuffer.
Application programs can access the KCMS library directly through the KCMS application programming interface (API). If you purchased the Software Developer's Kit (SDK), see the KCMS Application Developer's Guide for detailed information on the KCMS API.
10.5.1.1 Calibrated Profiles and Visuals
When Calibrator Tool calibrates your monitor it produces one calibrated profile for each frame buffer's visual. When images are displayed on a monitor, two conditions may exist that affect whether the resultant color appears the same on two different devices: the slow shifting of color and the use of X visuals.
Recalibrating corrects the slow shifting of color. Your frame buffer's hardware gamma lookup table (LUT) corrects X visuals. A visual is a data structure describing the display format a display device supports. The visual describes the display characteristics for each pixel in the window. In other words, a window's visual instructs the display device's hardware gamma LUT how to interpret the value of the window's pixels. When the visual goes through the gamma LUT, it is then corrected.
If the KCMS software calibrates a corrected X visual, the resultant color will not appear the same on two different devices because the visual will be gamma corrected twice. The KCMS software determines if the X visual has been corrected with a hardware gamma LUT to ensure color consistency. For more information on X visuals and hardware gamma LUTs, see the xgetvisualinfo(3) and xsolarisgetvisualgamma(3) man pages.
The calibrated profile that describes your monitor is copied to the /etc/openwin/devdata/profiles directory. Read-only nominal profiles are in /usr/openwin/etc/devdata/profiles.
A copy of the profile you select with Calibrator Tool (see "10.5.4.2 To Select a Monitor") is made for each type of color visual supported by your frame buffer. GrayScale or StaticGray visuals are not considered because they are not color visuals. If your frame buffer supports both PseudoColor and TrueColor visuals, two or more sets of measurements will be taken by Calibrator Tool.
10.5.2 Adjusting Your Viewing Environment
You can make many adjustments to your monitor and working environment to create a good viewing environment. A good viewing environment reduces stress on your eyes. Before you calibrate your monitor establish a good viewing environment. Adjustments are either related to your working environment or your monitor. Make the working environment adjustments with your monitor turned off; make the monitor adjustments with your monitor turned on.
See the following white papers provided on line in /usr/openwin/demo/kcms/docs for detailed information on adjusting your viewing environment:
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Reducing Eyestrain from Computer Monitors
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Video Monitor Adjustments: "Black Level" and "Picture"
10.5.2.1 Adjusting Your Working Environment
Make the following adjustments to your working environment with your monitor turned off:
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Minimize reflections
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Adjust ambient light
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Establish a suitable surround
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Establish a comfortable viewing distance
Note -You do not need to shut down your computer as long as your monitor has its own power switch.
Minimizing Reflections
Your screen has a glass faceplate that reflects--into your eyes--light that originates behind you. Reflections can change your perception of your display at the location where it is reflected. The flatter your monitor's faceplate, the less of a problem reflections are likely to be; a highly curved screen "collects" reflections over a wide angle behind you.
To determine whether your screen has reflections, sit in your normal working position and examine the dark screen for reflections. (The reflections may be distorted by the curvature of the screen.) Try to arrange your environment so that no intense light sources are reflected on your screen. If you cannot move your furniture, either move the light source or block your (reflected) view of the offending object with dark cardboard baffles.
Your monitor's screen may have an integral antiglare coating or treatment to minimize glare. A monitor with this treatment appears to have a very dark screen when it is turned off. You can attach an external antiglare screen to the front of your monitor, but some antiglare screens have such low light transmission that you may find that they reduce the intensity of white to an unacceptably low level.
Adjusting Ambient Light
Not only can you see light that originates behind you, but you can see objects other than light, like your own silhouette. To minimize reflections of objects in front of your screen other than lights, reduce the general light level, or ambient illumination. Overhead fluorescent light is usually the cause of this type of reflection because it is excessively bright. Use a different light source (for example, lamps) if this type of reflection occurs.
Establishing a Suitable Surround
Visual stress is induced if--while watching your screen--your peripheral vision is exposed to a light intensity substantially brighter than the brightest regions of your display. The color science term surround refers to the area perceived by your peripheral vision while you are looking at a display. In addition to disturbing your peripheral vision, a bright surround increases your ambient illumination. Try to establish a visual surround that is darker than the brightest white of your screen.
It is beneficial to have a visual reference to the outside world--such as a window to the outdoors--while working at your computer. If you have a window, make sure you sit so that the window is far enough to your side that it does not impinge your peripheral vision, but not so far behind to reflect in your screen.
Establishing a Comfortable Viewing Distance
If you can see individual pixels on your screen, you are probably sitting too close to your screen. Visual recognition skills, particularly reading, develop on the basis of recognizing shapes, not dots. When you look at the letter "V", you should perceive two angled intersecting straight lines, not two jagged vertical elements or a collection of dots.
For minimum stress viewing of your screen, you should work at a sufficient distance so that you cannot see individual pixels on the screen. A sufficient distance is usually at arm's length. Extend your arms in front of you while you are sitting at your workstation. The tips of your fingers should reach the faceplate of your screen. The arm's-length viewing distance minimizes stress due to focusing at short distances for an extended period of time.
If you have trouble making out characters at a viewing distance sufficient to blend pixels into shapes, consider using a larger font for viewing on the screen.
10.5.2.2 Adjusting Your Monitor
Once your working environment is set up properly, let your monitor warm up for at least one hour adjust your monitor's Black Level and Picture.
This
icon indicates the Picture (or Contrast) control. It affects the brightness
that is reproduced for a full white input signal. Once Black Level is set
correctly, Picture should be set for comfortable viewing brightness.
This
icon indicates the Black Level (or Brightness) control. This control should
be adjusted so that black picture content displays as true black on your monitor.
Incorrectly adjusting this control is the most common problem of poor quality
picture reproduction on computer monitors, video monitors and television sets.
A monitor is properly adjusted when it meets these conditions:
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A black input signal should produce true black to maximize the contrast ratio of the display
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A white input signal should produce the desired intensity
10.5.2.3 To Adjust Your Monitor
Follow these steps to properly adjust your monitor.
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Turn your monitor's Picture control to minimum to display a black picture.
The
minimum setting of the Picture control causes the picture content to disappear
entirely. If your monitor's picture cannot be made to vanish, then you will
have to arrange to display a picture that is substantially black (for example,
by activating a screen-saver). -
Turn your monitor's Black Level control to adjust black correctly.
Turn
the Black Level control to the balance point or threshold. The threshold is
low enough that a black area of the picture emits no light, but high enough
that setting the control any higher would cause the area to become a dark
gray. -
Turn your monitor's Picture control to adjust the brightness level.
Once
the black level is set correctly, the Picture control can be adjusted so that
a white signal produces the appropriate level of brightness. There is no proper
setting of this control; it depends entirely on your preference. Avoid setting your monitor too bright. Excessive brightness can increase your sensitivity to flicker, reduce the contrast ratio of the picture, and defocus the electron beam of the CRT, resulting in poor sharpness.
Note -You may need to iterate between the Black Level control and the Picture control a few times to set the combination that both reproduces black correctly and white at the brightness you desire.
10.5.3 Connecting the Calibrator Puck
Once you adjust your viewing environment, connect a monitor calibrator device (called a puck) to your workstation.
Note -
The puck is not mandatory, but it is highly recommended that you use it to calibrate your color monitor. If you do not have a puck, skip to "10.5.4 Running Calibrator Tool".
10.5.3.1 To Connect the Calibrator Puck
Connect your puck to either serial port A (1) or port B (2) of your workstation.
IA only -
Connect the puck to port 1. If your workstation does not recognize the new device (the puck), you may need to turn off your machine and reboot.
The puck sticks to your monitor's screen with a suction cup. See Step 4 for instructions on when to use the calibrator puck.
10.5.4 Running Calibrator Tool
Once you have adjusted your viewing environment, connected your puck (if you have one) and your monitor has warmed up for at least one hour, you are ready to run Calibrator Tool.
Run Calibrator Tool with kcms_calibrate in a command tool window. The kcms_calibrate program runs on Solaris 2.4 or 2.5 and requires a color frame buffer, or color monitor. Calibrator Tool takes approximately one minute to calibrate PseudoColor visuals and another minute to calibrate TrueColor visuals. If your framebuffer supports both types of visuals, allow at least two minutes for calibration.
10.5.4.1 To Start Calibrator Tool
Type kcms_calibrate to run Calibrator Tool.
The Setup window is displayed as shown in Figure 10-1.
Figure 10-1 Calibrator Tool Setup Window
10.5.4.2 To Select a Monitor
Before you press the Calibrate... button, you must choose a monitor.
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Click on Monitors.
A list of monitor profiles available in your environment is displayed as shown in Figure 10-1.
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Select a Monitor Type.
If you do not know the type of monitor you have, you can get general information about a monitor by clicking on the More... button. The information is displayed in a separate window. The following information is an example of the type of information given when you select a Sony 16" profile and press the More... button:
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Color space = RGB
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Device manufacturer = Sony
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Device model = 16"
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White point = 0.964294 1.000000 0.825104, press OK to dismiss window
You can also use Table 10-2to help you choose a monitor. The Sun part number is located on the monitor's nameplate. Find the part number on your monitor and match it to the part number in this table. Use the rest of the information in the row to choose a monitor.
Sun Part Number
Description
Manufacturer
Profile Description
365-1130-01
P3 16" Color
Sony
Sony 13/16/19" Monitor
365-1112-01
P3 19" Color
Sony
Sony 13/16/19" Monitor
365-1159-01
P3 16" Color
Sony
Sony 13/16/19" Monitor
365-1160-01
P3 19" Color
Sony
Sony 13/16/19" Monitor
365-1147-01
P3 16" Color SH (Southern Hemisphere)
Sony
Sony 13/16/19" Monitor
365-1148-01
P3 19" Color SH
Sony
Sony 13/16/19" Monitor
365-1288-01
P3 19" Color Logoless
Sony
Sony 13/16/19" Monitor
365-1289-01
P3 16" Color Logoless
Sony
Sony 13, 16 and 19" Monitor
365-1153-01
Skol 19" P3 MPR2
Sony
N/A
365-1151-02
Rosebud 17" Mid Range (MR) Color
Sony
N/A
365-1166-02
Rosebud 17" MR Color Logoless
Sony
N/A
365-1164-02
Rosebud 17" MR SH Color
Sony
N/A
365-1165-02
Rosebud 17" MPR2 MR
Sony
N/A
365-1068-01
21" Color
Toshiba
N/A
365-1286-01
Tulip 15" FS Color
Nokia
Sony 15" Monitor
365-1167-01
Corona P4 20" Color
Sony
Sony 20" Monitor
365-1313-01
Corona P4 20" Color Logoless
Sony
Sony 20" Monitor
365-1317-01
Corona P4 20" Color SH
Sony
Sony 20" Monitor
365-1316-01
Jasmine 17" N1 Color
Sony
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10.5.4.3 To Calibrate a Monitor
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Click on Calibrate...
A separate window is displayed asking you to choose a device as shown in Figure 10-2.
Figure 10-2 Calibrator Devices Window
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Choose a device.
If you have a puck that correlates to a device in the list, choose that device.
If you do not have a puck, choose XSolarisVisualGamma. The calibrated profile is based on the gamma values stored in the LUT for your specific frame buffer.
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Click on Load.
If you have a puck, a separate window will be displayed as shown in Figure 10-3. It is the Calibrator Profile window with a medium gray circle. This circle will be in the middle of your screen.
Figure 10-3 Calibrator Profile Window
The center of your screen provides the most accurate readings. Do not move the window, and since calibration takes several minutes, be sure that no extraneous window (like a pop-up dialog) will obscure the calibration window until calibration is complete.
If you do not have a puck, the Calibrator Profile window will be displayed. You do not need to worry about moving the window or pop-up dialogs. Skip to Step 5.
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If you have a calibrator puck, place it firmly in the center of the circle.
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Click on the Start... button.
After a few seconds, the circle becomes cyan and calibration begins.
Depending on the type of frame buffer you have, the measurement cycle (for red, green and blue) may repeat a second time. If your frame buffer supports both PseudoColor and TrueColor visuals, two sets of measurements will be taken. If the frame buffer implements only one of these types, only one set of measurements is taken.
If a pop-up dialog appears in the middle of the color circle, you must restart the calibration. The calibration data is now contaminated and will produce inaccurate measurement data. See "10.5.4.4 To Interrupt Calibration"for information on halting calibration.
When the tool has completed reading measurements, the monitor's profiles are updated and a message is displayed informing you that calibration is completed.
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Remove the calibrator puck from the screen.
Once calibration is completed, remove the puck from the screen. Store it in a position that prevents dirt and dust from gathering on its glass faceplate.
10.5.4.4 To Interrupt Calibration
Click on Stop.
A separate window is displayed asking if you want to continue calibration or exit. If something obstructed the calibrator puck from reading the circle, you must exit and then restart calibration.
Calibration does not halt until the current color has been completely measured. For example, if you click on Stop while the Red measurement indicator is at 24, calibration will continue until Calibrator Tool is finished measuring Red (when the indicator is 255).
10.5.4.5 To Quit Calibrator Tool
Click on Quit.
You can then quit the Calibration window and quit Calibrator Tool.
10.5.5 Error Messages
Error messages you might get while running Calibrator Tool are described below.
10.5.5.1 Swap Space
Swap space errors indicate a memory allocation error. You may have too many applications running or you may need more swap space. The following swap space error messages tell you to quit some applications and restart Calibrator Tool:
10.5.5.2 Package Installation
Package installation errors indicate that the KCMS packages were not installed properly. The following package installation error messages tell you to reinstall the KCMS packages:
10.5.5.3 Puck Connection
Puck connection errors indicate a communication problem with Calibrator Tool and the calibration puck. You may not have the puck connected firmly in a port or connected to the correct port.
IA only -
The puck must be connected to port 1.
The following puck connection error messages tell you to check that the calibrator is plugged in firmly to either serial port A or serial port B of your workstation:
10.5.5.4 OWconfig Data
OWconfig error messages indicate that data in the OWconfig data base is corrupted. Check your OWconfig file for an incorrect entry. You should EXIT and restart Calibrator Tool.
10.5.5.5 Device Handler
The device handler error message indicates there is no device handler for the selected device. Calibrator Tool cannot load the calibration module. You should install the device handler in the /usr/openwin/etc/devhandlers directory or select another device.
10.5.5.6 Module Initialization
The module initialization error indicates that a module was not able to finish initialization. You need to EXIT or use another shared object.
10.5.5.7 Incomplete Module Measurement
Incomplete module measurement error messages indicate that the module did not successfully complete measuring your monitor's luminance. This is usually caused by you pressing the Stop button. You should EXIT Calibrator Tool or Close the dialog and restart calibration.
10.5.5.8 Invalid Profile
The invalid profile error messages indicates you cannot calibrate the profile you have selected. You should select a valid profile.
10.5.5.9 Private Colormap Entry Allocation
The private colormap entry error message indicates that Calibrator Tool could not allocate the entry. You need to make sure you are running the window server with an available dynamic visual because Calibrator Tool specifies its own color(s). You should either EXIT Calibrator Tool or restart calibration.
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