Multiscan Computer Displays with FD Trinitron

GDM-F500 and GDM-F400

FD Trinitron Unprecedented image performance, featuring the finest aperture grille pitch available (0.22mm) and flattest Trinitron display ever, gives demanding CAD and graphic professionals the edge F Series
Tightest Aperture Grille Pitch Available 0.22mm aperture grille pitch across the entire screen Bright Picture, Sharp Images Sonys new HiDensity Electron Gun with Enhanced Elliptical Correction System technology Digital Multiscan Technology Supports the broadest range of PC and Mac display resolutions Stable, Consistent Color And Images Sonys GeoLockPlus circuitry provides improved color and brightness uniformity Easy To Navigate On-Screen Display DisplayMouse control allows for quick, smooth adjustments of the digital controls Instant Sizing And Centering Of Image Active Signal Correction (ASC) circuitry provides easy image adjustment at the touch of a single button Generalized Timing Formula (GTF) - Insures compatibility with varying video standards, reduces set-up time and maximizes the performance of the display system Reduced Depth Design Smart cable design allows for overall shorter depth of display on desktop Comprehensive Digital OSD Six languages with features such as image zoom, color and temperature adjustment, control lock, landing correction and information screen Dual Input Control 15 pin mini D-sub and 5 BNC connector options USB Compatibility Self-powered USB hub built into base with one upstream and four downstream ports
GDM-F500 Sony FD Trinitron Computer Display
CRT: 21" FD Trinitron (19.8" Viewable Image Size) Horizontal Scan Range: 30-121kHz Vertical Scan Range: 48-160Hz Maximum Resolution: 1800 x 1440 @ 80Hz Dimensions (WxHxD): 19.8" x 20.0" x 19.1" Weight: 70.5 lbs
GDM-F400 Sony FD Trinitron Computer Display
CRT: 19" FD Trinitron (18" Viewable Image Size) Horizontal Scan Range: 30-107kHz Vertical Scan Range: 48-120Hz Maximum Resolution: 1600 x 1200 @ 85Hz Dimensions (WxHxD): 17.5" x 18.7" x 17.9" Weight: 60.6 lbs

Specifications

CRT GDM-F500: 21" FD Trinitron GDM-F400: 19" FD Trintron Viewable Image Size GDM-F500: 19.8" GDM-F400: 18" Aperture Grille Pitch 0.22mm Screen Treatment Anti-Reflective Coating Electron Gun HiDensity Electron Gun with Enhanced Elliptical Correction System technology Horizontal Scan Range GDM-F500: 30-121kHz GDM-F400: 30-107kHz Vertical Scan Range GDM-F500: 48-160Hz GDM-F400: 48-120Hz Maximum Resolution GDM-F500: 1800 x 1440 @ 80Hz GDM-F400: 1600 x 1200 @ 85Hz Preset Resolutions (27 modes) 640 x 480 @ 60Hz VGA Graphics 640 x 480 @ 85Hz VESA 800 x 600 @ 85Hz VESA 832 x 624 @ 75Hz Macintosh 16" 1024 x 768 @ 75Hz Macintosh 19" 1024 x 768 @ 85Hz VESA 1152 x 864 @ 75Hz VESA 1152 x 870 @ 75Hz Macintosh 2-page 1280 x 1024 @ 75/85Hz VESA 1600 x 1200 @ 75/85Hz VESA 1800 x 1350 @ 85Hz Sony (GDM-F500 only) 1800 x 1440 @ 80Hz Sony (GDM-F500 only) and others Color Temperature Presets 5000 Kelvin 6500 Kelvin 9300 Kelvin 3 User-Adjustable Settings (Bias/Gain Control) Signal Inputs Analog RGB 0.7Vp-p, 75ohm Termination External Sync Signals Separate/Composite 1-5Vp-p, polarity-free TTL Sync on Green: 0.3Vp-p, negative Input Connectors 15 pin mini D-sub and 5 BNC connectors Power Requirements 100-240V AC; 50-60Hz Power Management International Energy Star, NUTEK and VESA DPMS Compliant GDM-F500 Operation: 140 watts (maximum) Suspend: 8 watts (maximum) Active Off: 1 watt (maximum) Power Off: <1 watt GDM-F400 Operation: 160 watts (maximum) Suspend: 10 watts (maximum) Active Off: 3 watts (maximum) Power Off: <1 watt Dimensions (WxHxD) GDM-F500: 19.8" x 20.0" x 19.1" GDM-F400: 17.5" x 18.7" x 17.9" Weight GDM-F500: 70.5 lbs GDM-F400: 60.6 lbs Operating Temperature 50F-104F (10C-40C) Operating Humidity 10%-80% (Non-Condensing) Regulation Compliance Safety: UL 1950 CSA 22.2 No. 950 EN60950 (TUV, GS mark) Emission/EMI: FCC Class B IC Class B MPR II TUV (full compliance) TCO 95 X-ray: DHHS DNHW PTB Ergonomics: ZH1/618, ISO9241-3, 8 Designed for: Microsoft Windows 2000 Windows 98 Macintosh Compatible Plug & Play: DDC-1, DDC-2B/A, DDC-CI DMI Compliant VESA: Generalized Timing Formula (GTF) Front Panel Digital Controls Power On/Off Active Signal Correction (ASC) Reset Brightness Contrast Input Switching Button On-Screen Display (OSD) Brightness/Contrast H/V Size H/V Centering Zoom Raster Rotation Pincushion Pin Balance Keystone Key Balance Color Temperature H/V Convergence: Top/Bottom Landing Correction (4 Corners) Moir Cancellation Manual Degauss Power Save Delay H/V OSD Position Control Lock Multi-Language Select (6 languages) Supplied Accessories Tilt Base/Wide Angle Swivel (90) Stand Video Signal Cable (15 pin mini D-sub) AC Power Cord Macintosh Adapter Windows 95/98 inf. Diskette USB Cable Limited Warranty 3 Years - Parts, Labor and CRT

F Series

The Multiscan FD Trinitron displays offer the very latest in advanced CRT display technology from Sony: the FD Trinitron CRT. These virtually flat CRTs minimize geometric distortion and reduce reflective glare that may cause eyestrain. Designed with the demanding CAD and graphic professionals in mind, the Multiscan F Series sets a new level of image performance, ease of use and reliability. The stunning images produced by this display are a result of Sonys new HiDensity Electron Gun with Enhanced Elliptical Correction System technology. The tight 0.22mm aperature grille pitch delivers sharp, detailed color images consistently across the entire screen especially in the corners. Digital Multiscan and Active Signal Correction (ASC) technologies allow for easy set-up, regardless of the input signal or resolution. And with broad horizontal scan rates available, resolutions as high as 1800 x 1440 @ 80Hz (F500) are possible. Our unique DisplayMouse control is easy-to-use and allows for precise manual adjustment of the image to fit individual user preference. Sony left nothing to the imagination with this display, including GeoLock Plus circuitry. This feature will automatically sense and neutralize electromagnetic fields that can cause image or color distortion, which is commonly noticeable on large screen displays. The F Series is designed for Windows 2000 and Windows 98, is Macintosh compatible and meets or exceeds all of the industry safety standards, including TCO 95 compliance.
Sony Electronics Inc. Information Technologies Marketing Division 3300 Zanker Road, San Jose, California 95134 For more information: 1.800.352.SONY Web address: http://www.sony.com/displays
Computer Interface: The computer industry lacks standards, and therefore, there are a multitude of varying software packages and add-on hardware options. This display is not manufactured to any specific software, and Sony does not and cannot make any warranty or representation with respect to the performance of this product with any particular software packages and/or non-Sony add-on hardware option except those mentioned in this document. Sony hereby disclaims any representations or warranty that this product is compatible with any combination of non-Sony products you may choose to connect. While Sony representatives or Sony authorized dealers may be able to assist you and may make recommendations, they are NOT authorized to vary or waive this disclaimer. Purchasers must determine for themselves the suitability and compatibility of the hardware and software in each and every particular instance. 1999 Sony Electronics Inc. All rights reserved. Reproduction in whole or in part without written permission is prohibited. Sony, the Sony logo, displays by sony, Multiscan, Trinitron, FD Trinitron, Digital Multiscan, HiDensity Electron Gun, GeoLock Plus, DisplayMouse, ASC and Enhanced Elliptical Correction System are trademarks of Sony. Microsoft, the Windows Logo and Windows 2000 are registered trademarks of Microsoft Corporation. Macintosh and Mac are trademarks of Apple Inc. Features and specifications are subject to change without notice. Non-metric weights and measurements are approximate. This monitor is Energy Star Compliant when used with a computer equipped with VESA Display Power Management Signaling (DPMS). As an International Energy Star Partner, Sony Corporation has determined that this product meets the International Energy Star Program for energy efficiency. The Energy Star emblem does not represent EPA endorsement of any product or service. D174 Printed in U.S.A. 01/99

Silicon Graphics 1600SW Flat Panel Monitor
The 1600SW display was driven by a SGI Visual Workstation 320. The SGI ColorLock sensor and software was used to calibrate the display to the sRGB setting (D65 white point, gamma of 2.2) prior to making measurements. 1.1.1 Product Features
The 1600SW is an active matrix digital LCD, flat panel display with a SXGA-wide (1600 x 1024) format. Product features include: Adjustable white balance via software and dynamic backlight adjustment. Accurate to within 25K. ColorLock system which uses factory characterization data stored within the onboard memory of each monitor and a specially designed photopic sensor to self-correct the panel. 1.1.2 Display Defects
As with most LCD panels on the market today, defects are common due to high manufacturing costs. The most common defects are weak pixels and ones that are stuck in one state which appear as unchanging bright or dark spots depending on the display mode (normal bright vs. normal dark). Silicon Graphics allows no more that 5 green defects per monitor, with no more than a total of 8 bright defects of all colors combined. On the particular display used in this study (SN 92000350N), there are two noticeable on red pixels near the edge of the screen. 1.1.3 Viewing Angle
One of the major issues facing the designers of LCD displays is viewing angle. The pixels of an LCD display do not emit light (as in a CRT) but rather obtain it from a backlight source and transmit it along their molecular axes. Since the twisted-nematic liquid crystals exhibit birefringence, changes in viewing angle lead to changes in appearance. SGI defines the viewing angle of their displays to be the range of angles giving acceptable contrast ratios and linear gray scales. This display claims a viewing angle of 120 horizontal, +45/-55 vertical. From casual observation of the display, these values seems to be correct. 1.1.4 Further Information
More information can be found on SGIs web site at: www.sgi.com/peripherals/flatpanel A well written introduction to LCD display technologies, as well as the specific advances made in the SGI display can be found at: www.sgi.com/peripherals/flatpanel/whitepapers.html 3

In this section: All rights reserved by Silicon Graphics, Inc. are trademarks of Silicon Graphics Inc. 1.3 IBM
The IBM prototype display called Roentgen is a 200ppi digital active matrix TFTLCD display with a QSXGA (2560 x 2048) format. To avoid the need for special high-end adapter, the screen is controlled by four separate SXGA display adapters each driving one quarter of the screen. 1.1.1 Display Defects
As with the SGI display, several defects are present in the IBM display. Being a prototype however, they are more widespread, and varied. Although every effort was taken to minimize their impact, many of them were unavoidable in the measurement area. Such defects would not be present in a final product. Shot Boundaries Ten regularly spaced vertical bands appear across the width of this unit, each one corresponds to a single exposure in the photolithography process used in manufacturing the panel. Slight miss-alignment of the edges cause a mach banding effect, emphasizing their appearance, especially on light backgrounds. These can be eliminated using better alignment control. White Blobs Several small white blobs are visible on the screen which are caused by a disruption in the cell block creating an interference condition. These can be eliminated or screened out in manufacturing. Black Blobs A noticeable black blob caused by contamination on the back polarizer is also present. Line Defects Since LCD displays are essentially accessed in a row/column format, any missed connection in the 1.6 miles of specially formulated thin-film copper wire can cause an entire row or column of pixels to be unaddressable. A white line also appears in several locations due to weak gate lines. IBM has developed technologies to minimize these defects in the prototype unit. Horizontal Smudges One area on the display has a smudged appearance on the front glass due to residual chemicals left from hand buffing the polyamide layer which aligns the liquid crystals. Uneven Illumination For the prototype display, an off-the-shelf back light system was used since the increased resolution was the primary focus. A customized back light unit as is used in the SGI display will improve both the intensity and uniformity of the back light in production units.

Viewing Angle

The viewing angle of the IBM display very limited. Even small shifts in viewing position alter the appearance of the image. This is because no effort has been made to minimize the angular dependency in this prototype. A commercial version of the display would require much improvement in this area. 1.1.3 Further Information
Information about Roentgen can be found at: www.research.ibm.com/news/detail/factsheet200.html In this section: All rights reserved by IBM Inc. 1.4 Summary Comparison or in [Bassak 1998].
The table below lists the key features of each display for comparison. Table 2-1Summary Comparison of Display Physical Characteristics

Viewing Size Resolution Pixel Pitch Number of Pixels Bits per channel Luminance Weight
Sony GDM-F500 19.8 Diagonal ~72 ppi 0.22 mm 1280H x 1024V @80Hz cd/m2 (427:1 contrast) 70.5 lbs.
SGI 1600SW 17.3 Diagonal 110 ppi 0.231 mm 1600H x 1024V cd/m2 (276:1) 16 lbs.
IBM Roentgen 16.3 Diagonal 200 ppi 0.126 mm 2560H x 2048V cd/m2 (205:1) < 20 lbs.
Please note the following points: In this comparison, viewing size is defined as the diagonal size of the viewable area of the display. The number of pixels figure for the Sony CRT is the setting used for this evaluation, it is capable of many other configurations. Luminance measurements were made on a central 3.5" square surrounded by mid gray.

Spectral Characteristics

A useful property when characterizing a display is that of stable primaries. To examine the spectral stability of the displays primaries, a series of four logarithmically spaced patches {35,81,145,255} was displayed for each primary and measured with the PR704. A five step ramp, including black, was also measured. If the primaries were spectrally stable, the normalized plots of each ramp shown in the figures below would appear as a single curve. During the measurement process, every effort was made to keep the PR704 perpendicular to the display to minimize angular effects. At the distances used for measurement, the 0.5 circular aperture spanned approximately 20 pixels on the display. While the PR704 provided data from 380780nm at 2nm intervals, only the range from 400700nm was evaluated in this section. If the tristimulus values used in subsequent stages were to be calculated from this data it is suggested that the range be extended to at least 720nm to capture the red phosphor emission near 710nm [Berns 1993b]. Issues such as the tradeoff between bandpass and sampling increment must also be addressed. Since a very accurate colorimeter, the LMT C1200, was available which gives tristimulus values directly, these spectral measurements were made primarily for illustrative purposes.
The spectral radiance characteristics of the Sony display are shown in the figures below. Figure 2-1 shows the spectral radiance distribution of the white. Figure 2-2 shows the corresponding plot for the displays black. Plots of the normalized ramps are show in Figure 2-3 Figure 2-6 below. In these figures the solid line represents the full on primary {level 255}, and the broken lines the intermediate levels. Figure 2-1Sony Display White Radiance

White 5.0E-03

Radiance (W/m2sr)
4.0E-03 3.0E-03 2.0E-03 1.0E-03 0.0E+550 Wavelength (nm) 700
Figure 2-2Sony Display Black Radiance

Black 2.0E-05

1.6E-05 1.2E-05 8.0E-06 4.0E-06 0.0E+550 Wavelength (nm) 700
Figure 2-3Normalized Gray Ramp

Gray 1.0

Relative Power

0.8 0.6 0.4 0.2 0.550 Wavelength (nm) 700
Figure 2-4Normalized Red Ramp

Red 1.0

Figure 2-5Normalized Green Ramp

Green 1.0

Figure 2-6Normalized Blue Ramp

Blue 1.0

Based on the figures above, it would appear that the Sony display exhibits reasonable spectral stability as to be expected from a good quality CRT. From spectral measurements such as these, the purity of each channel can be readily evaluated. For example, the strong peak near 630nm from the rare-earth elements used in the red phosphor is visible in both the green and blue channels.
The corresponding measurements for the SGI display are given below. The white, shown in Figure 2-7, is characteristic of the fluorescent backlight utilized in this display. The non-zero radiance for the black state, Figure 2-8 (compare to Figure 2-2), is common for LCD displays as the polarizes are unable to fully extinguish the backlight and a small amount leaks through. Figure 2-7SGI Display White Radiance

White 1.2.E-02

1.0.E-02 8.0.E-03 6.0.E-03 4.0.E-03 2.0.E-03 0.0.E+550 Wavelength (nm) 700
Figure 2-8SGI Display Black Radiance

Black 3.0.E-05

2.5.E-05 2.0.E-05 1.5.E-05 1.0.E-05 5.0.E-06 0.0.E+550 Wavelength (nm) 700
Figure 2-9Normalized Gray Ramp
Figure 2-10Normalized Red Ramp
Figure 2-11Normalized Green Ramp
Figure 2-12Normalized Blue Ramp
The normalized plots of each channel appear to have greater variability than was seen in the Sony monitor, especially in the blue. Furthermore, the characteristics of the fluorescent backlight are visible in all three channels.
Measurements on the IBM display follow. Again, the characteristics of the fluorescent backlight are clearly visible from the white shown in Figure 2-13. Figure 2-13IBM Display White Radiance
White 1.4.E-02 1.2.E-02 1.0.E-02 8.0.E-03 6.0.E-03 4.0.E-03 2.0.E-03 0.0.E+550 Wavelength (nm) 700
Figure 2-14IBM Display Black Radiance

Black 8.0.E-05

6.0.E-05 4.0.E-05 2.0.E-05 0.0.E+550 Wavelength (nm) 700
Figure 2-15Normalized Gray Ramp
0.8 0.6 0.4 0.2 0.550 Wavelenght (nm) 700
Figure 2-16Normalized Red Ramp
Figure 2-17Normalized Green Ramp
Figure 2-18Normalized Blue Ramp

2.4 2.4.1

Summary Comparison Peak Spectral Radiance
Table 2-1 compares the peak spectral radiance output of each display for white, black, and the primaries. The two LCD displays have higher peak radiance in all three channels than the conventional display, due in part to the use of the narrow-band fluorescent backlights. Table 2-1Peak Spectral Radiance Values for Each Display Peak Radiance (W/m2sr)E-03 White Point Black Red Green Blue 2.4.2 Sony 3.94 0.02 3.83 0.75 0.83 SGI 10.9 0.03 5.5 8.8 3.4 IBM 12.0 0.07 8.2 11.0 2.4

Spatial Independence

Spatial independence refers to the impact that a color displayed on one area of the monitor has on a color in another area. Characterizing a display that does not exhibit this property is difficult if not impossible. To test the spatial independence of each display, a series of nine color stimuli were measured on nine different background made up of the same nine colors for a total of 81 colorimetric measurements [Fairchild 1998]. The CIELAB coordinates of each stimulus were then computed using the average value of white on gray as the CIELAB reference white. The data are summarized in Table 4-1 for each display using mean color-difference from the mean (MCDM) metrics in terms of CIE94 color differences. The MCDMs were calculated both across background (i.e. how did the nine different backgrounds affect each of the foreground colors), and across stimuli (i.e. how much did the nine different foreground colors change on a given background). The data in this section were not flare corrected since only changes are compared. Table 4-1MCDMs for Spatial Independence Measurements Color Black {0} Gray{128} White {255} Red {128} Red {255} Green {128} Green {255} Blue {128} Blue {255} Sony Background Stimuli 0.76 1.67 0.18 0.53 1.68 0.44 0.42 0.64 0.52 0.32 0.53 0.32 0.44 0.26 0.63 0.92 0.38 0.43 SGI Background Stimuli 0.10 0.03 0.07 0.26 0.14 0.07 0.08 0.05 0.06 0.04 0.09 0.12 0.05 0.03 0.08 0.07 0.06 0.05 IBM Background Stimuli 0.15 0.13 0.15 0.48 0.17 0.25 0.23 0.23 0.22 0.13 0.19 0.31 0.28 0.12 0.19 0.14 0.27 0.06
The overall MCDM for the SGI display was 0.08, 0.21 for the IBM, and 0.62 for the Sony display. Given that each pixel in an active-matrix TFT-LCD is physically distinct from its neighbors, good spatial independence was expected. In a conventional CRT, a single scanning electron beam is used to address each pixel of a given color and they often suffer from poor spatial independence.

Luminance & Contrast

Using the LMT L1009 photometer, the luminance of each primary, black, and white was measured. The contrast of the display was then calculated by taking the ratio of the white to the black. Results are summarized in the tables bellow. The targets were displayed as both full-screen colors, Table 5-1, and as 3.5" squares with gray surround, Table 5-2, for comparison. The large difference in values point to the need for carefully defining the measurement conditions before stating results. Table 5-1Measured Luminance and ContrastFull Screen Color Red Green Blue White Black Contrast (W/K) Sony (cd/m2) 15.47 36.0 3.51 55.8 0.004 13950:1 SGI (cd/m2) 44.5 110.3 13.81 167.8 0.541 310:1 IBM (cd/m2) 38.3 93.9 11.92 150.7 0.665 227:1

Table 5-2Measured Luminance and Contrast3.5" Square with Gray Surround Color Red Green Blue White Black Contrast (W/K) Sony (cd/m2) 15.70 39.3 3.96 55.9 0.131 427:1 SGI (cd/m2) 42.9 106.4 13.34 161.5 0.584 276:1 IBM (cd/m2) 38.4 94.5 12.19 152.7 0.745 205:1
Comparing the two tables above, it can be seen that the two LCD panels maintained their black level, and therefore contrast as the target size was reduced. Given the nature of the LCD display, it is expected that this would hold even for very small targets. In comparison, the CRT had an extremely large contrast with a full screen measurement, but a more moderate contrast when the target was reduced in size. Reducing the target size further would cause still more reduction in contrast.
The full screen luminance of the Sony monitor is more than a factor of two lower than either of the two LCD displays tested but is typical of most good quality CRT displays. The full screen contrast ratio however was quite high for the Sony display. When properly setup, little to no light is emitted from the black state on a CRT. 5.2 SGI
The SGI monitor has the highest luminance output of the thee monitors tested in this report. While not as high luminance as the Apple Studio display measured by Fairchild [1998] which measured 188 cd/m2, the SGIs contrast ratio was considerably higher (310:1 vs. 250:1) indicating a darker black level. The measured contrast ratio is on par with the manufactures claim of 350:1. To achieve this SGI uses two techniques. First, a negative birefringence compensation film is placed after the liquid crystal cell to compensate for the positive birefringence introduced by the liquid crystal giving a greater extinction level. Second, thick color filters are used to maintain high saturation levels in the primary color subpixels thus minimizing the impact of any stray leakage from adjacent pixels. 5.3 IBM
The weaker performance of the IBM display is most likely due to its prototype nature and will be likely be improved upon in the commercial version.
Chromaticity Constancy of Primaries
The gain-offset-gamma (GOG) model for characterizing displays uses a two stage process. First, three 1D-LUTs are used to transform the incoming digital counts into linear scalars. Second, the linear scalars are multiplied by a 3x3 primary mixing-matrix. Thus the estimated signal is a scaled version of the full strength primaries. For this process to work, the chromaticity coordinates of each level must remain constant. To test this assumption, a series of 16 logarithmically spaced steps in red, green, blue were measured along with a 17 log-step gray ramp. As discussed by Fairchild [1998], the black level flare has been removed from each measurement before computing the chromaticities. Results for each display are given below. 6.1 Sony
Figure 6-1Chromaticity of Red, Green, Blue Primaries and Neutrals

0.7 0.6 0.5 0.4

0.3 0.2 0.1 0.0 0.0 0.1 0.2 0.3 x 0.4 0.5 0.6 0.7
The primary constancy of the Sony display appears adequate, as is expected of a high quality CRT. The tendency of each primary towards the white point may indicate that some residual flare was not accounted for. The large variation in the gray levels is due primarily to the undefined nature of chromaticity coordinates at very low tristimulus values.
Figure 6-2Chromaticity of Red, Green, Blue Primaries and Neutrals
The SGI display appears to exhibit good consistency in the primaries and has a stable gray scale. The one outlying point in the gray ramp is the black. The tristimulus values of the black patch, after subtracting the average flare value, were slightly non zero {-0.001, -0.0008, -0.0007} and therefore produced an outlying point in chromaticity space rather than being undefined if it measured {0,0,0}. In practice these small deviations from zero are insignificant and would be removed, their inclusion here is simply illustrative.
Figure 6-3Chromaticity of Red, Green, Blue Primaries and Neutrals

0.7 0.6 0.5

0.4 0.3 0.2 0.1 0.0 0.0 0.1 0.2 0.3 0.4 x 0.5 0.6 0.7 0.8

Summary Comparison

To summarize the variability of each displays primaries, Table 6-1 lists the coefficient of variation in both the x and y dimensions for each primary. Table 6-1Chromaticity Variability Color Red Green Blue Gray x 0.01 0.01 0.06 0.09 Sony y 0.00 0.03 0.31 0.01 x 0.01 0.01 0.01 0.02 SGI Y 0.01 0.01 0.15 0.01 X 0.01 0.02 0.08 0.03 IBM Y 0.02 0.01 0.07 0.02

Additivity

The additivity of each display was evaluated in both luminance, Table 7-1, and tristimulus space, Table 7-2. Luminance values were measured with the LMT L1009 photometer at a distance such that its 1 spot size spanned approximately 20 pixels on the display. The LMTC1200 colorimeter used for tristimulus measurements has a 3" diameter aperture and is set 2.25" back from the front surface of the device by means of a matte black tube. All tristimulus values in this section were flare corrected by subtracting the average tristimulus values of the black squares measured (8 in all) from the corresponding values of each sample. Results for each display are discussed in the various subsections below. Table 7-1Luminance Additivity Color Sony (cd/m2) R+G+B 54.98 White 55.8 Difference 1.5% SGI (cd/m2) 168.61 167.8 -0.5% IBM (cd/m2) 144.12 150.7 4.5%
Table 7-2 Tristimulus Additivity Value White Sony R+G+B 35.53 36.70 32.77 % Diff. 0.70% 0.63% 1.46% White 84.83 87.40 69.02 SGI R+G+ B 84.82 87.33 68.96 % Diff. 0.01% 0.08% 0.09% White 75.92 81.32 41.46 IBM R+G+ B 70.14 75.21 40.22 % Diff. 7.61% 7.51% 2.98%

X 35.78 Y 36.94 Z 33.26

The small failure of additivity for this display might well be due to a small increase in flare at the high luminance levels which is not present when estimating the flare from black alone. There may also be circuitry on board the display which increases power sent to the electron guns to compensate for their increased load. The degree of additivity is sufficient to justify the use of a 3x3 primary matrix transform. 7.2 SGI
The additivity on this display was excellent, exceeding many other displays we have tested. Given the high resolution of this display and the discrete nature of each pixel, it is not surprising that the additivity was good. The use of the 3x3 primary matrix transform is well justified. 7.3 IBM
The large differences between white and R+G+B are disturbing. A possible cause may be the strong angular dependency of this display. The LMT colorimeter was used with a very large acceptance cone and may therefore be subject to color shift errors. However, a substantial failure of additivity was also observed using various aperture sizes both with the LMT photometer and the colorimeter as shown in the table below. This issue is still under investigation. Table 7-3 Additivity vs. Aperture Size LMT Colorimeter Color Red Green Blue R+G+B White % Difference X 37.84 21.34 5.988 65.16 70.6 7.7% 3" Aperture Y Z 19.279 0.263 45.069 3.403 5.439 33.62 69.787 37.29 75.509 38.55 7.6% 3.3% 1" Aperture X Y Z 3.764 1.916 0.027 2.121 4.494 0.34 0.61 0.543 3.417 6.495 6.953 3.784 7.004 7.482 3.862 7.3% 7.1% 2.0% 0.5" Aperture X Y Z 0.749 0.381 0.005 0.421 0.892 0.066 0.121 0.108 0.675 1.291 1.381 0.746 1.385 1.483 0.76 6.8% 6.9% 1.8%
Table 7-4 Additivity vs. Aperture Size LMT Photometer Color Red Green Blue R+G+B White 6' 36.5 88.8 11.6 136.9 143.3 Aperture Size 20' 1deg 36.6 36.6 89.0 88.8 11.60 11.58 137.2 136.98 143.5 143.3 3deg 36.4 88.2 11.54 136.14 142.4 26

%Difference

Electro-Optical Transfer Functions
Being a conventional CRT display, the standard GOG model was used to characterize the Sony display. From a 17 step, logarithmically spaced gray ramp, target RGB scalars were estimated using the inverse 3x3 mixing matrix. Then, using a simplex nonlinear estimation, a constrained GOG model was fitted using Equation 8-1. The estimated parameters are given in Table 8-1, and the resulting curves are plotted in Figure 8-1Figure 8-3. Equation 8-1GOG Model Constrained to Gain+Offset=1.0

d = Gain c + ( Gain )

Where: refers to the red, green, or blue scalar (RGB).

Table 8-1Estimated GOG Parameters for Sony Monitor Channel Gain Gamma Red 1.0025 1.6553 Green 1.0200 1.7052 Blue 1.0200 1.7581 To test the fit of this model, the training data was estimated and the E*94 difference computed. Average error was 0.61, with a maximum of 1.13. A test with independent data is given in 9. Figure 8-1Measured Data and Fitted GOG model for the Red-channel
1.0 0.8 0.6 0.4 0.2 0.0.2 0.4 0.6 0.normalized digital count
Figure 8-2Measured Data and Fitted GOG model for the Green-channel

1.0 0.8 0.6

0.4 0.2 0.0.2 0.4 0.6 0.normalized digital count
Figure 8-3Measured Data and Fitted GOG model for the Blue-channel
Both a conventional GOG model using a 17 step neutral ramp, and a cubic spline interpolation of three 52 step ramps (red, green, blue) were used in modeling the SGI display. The estimated parameters of the GOG model are shown in the table and graphs below. Table 8-28-3Estimated GOG Parameters for SGI Display Channel Red Green Blue Gain 0.6706 0.8000 0.9507 Gamma 4.4622 3.2559 2.2841
The low estimated gain terms indicate a poor dark state. Preferably, the gain terms should all be slightly greater than 1.0 which creates negative offsets (offset = 1.0 - gain) and ensures that no light is being emitted at the black level. As with the Sony display, the fit of each model was evaluated by re-estimating the training data. Results for the two models tested for the SGI are shown in Table 8-4. An independent data set is evaluated in 10. Table 8-4Redistribution Errors for SGI Models Model GOG LUT Average E*94 2.94 0.97 Maximum E*94 6.72 2.2 Number of Points measured 17 logarithmically spaced gray patches 52 steps each for RGB, 156 total
Figure 8-4Measured Data and Fitted GOG model for the Red-channel
1.0 0.8 0.6 0.4 0.2 0.0.2 0.4 0.6 0.normilized digital count
Figure 8-5Measured Data and Fitted GOG model for the Green-channel
Figure 8-6Measured Data and Fitted GOG model for the Blue-channel
0.4 0.2 0.0.2 0.4 0.6 0.normilized digital count
Although the GOG model fit the low end reasonably well, the systematic trends to overestimate the high end indicated that this model might not perform well. Therefore, a set of three 1D LUTs were created from the 52 step primary ramps using cubic-spline interpolation between the nodes. The resulting transfer curves are shown below. Figure 8-7Measured Data and LUT for the Red-channel

In building the SGI-LUT and IBM models, a 17 step gray scale was measured twice as a check on repeatability. The average of these two sets forms a second independent data set to test these four models on as shown in Table 9-2 below. In the case of the Fit model, the two gray scales were included in the modeling set, so its inclusion in the table below is for comparison only. Table 9-2 E*94 Colorimetric Error for 17 Step Gray Scale Data Set
Model SGI (LUT) IBM (Peak) IBM (Scaled) IBM (Fit)
Average 0.78 2.71 2.07 2.15
Maximum 1.62 8.09 6.23 6.49
Overall, the model for the Sony display fit quite well as is typical of a properly set up high quality CRT. The good performance on both the redistribution test and the independent data set suggest that the model is robust and should perform well in subsequent testing. 9.2 SGI
As expected based on the systematic errors observed in the GOG model fits, the LUT based method preformed better on the SGI display. The LUT model should be adequate for most purposes and is on par to the results found by Fairchild [1998] for an Apple Studio display (average of 1.02, maximum of 2.88 on 100 independent samples). The LUT model performance on the Gray Scale data set was adequate. 9.3 IBM
Overall the IBM models performed less than satisfactory. It is hoped that, with further effort, a satisfactory and robust model can be derived. One possible solution in cases where models fail is to use a 3D look-up-table. Given the 64 levels of each primary there are a total of 643 = 262,144 possible colors (as opposed to the 16.77 million combinations for an 8 bit display). Therefore a reasonable sub-sampling, (perhaps an 13x13x13 target of 2197 patches, or around 0.8% of the total), of these levels could be measured. One of the three models could be used to up-sample the data to a full 64-cubed 3D LUT. An alternate solution might be to measure several hundred more patches and add them to the data set used in the Fit model. This would require fewer measurements and may provide adequate results. Failing that, the data could still be used as part of the 13-cubed sampling. Further analysis is needed before any definite conclusions can be drawn. The relative merits and weaknesses of each model tested are discussed in the following sections. 9.3.1 Peak Model

This model had the best redistribution performance of the three models tested. The average E*94 was 0.58 compared to 1.36 for the Scaled model and 1.19 for the Fit model. However, the performance on the 3x3x3 independent data set, and the gray scale data set was worse than the other two models as shown in Table 9-1 and Table 9-2.

Scaled Model

This model had the poorest redistribution performance of the three tested, though not totally unacceptable. The performance on the 3x3x3 independent data set, and the gray scale data set was better than either of the other two models but still higher than desired. 9.3.3 Fit Model
This model is interesting in that, while it was never the best model for any of the data sets tested, it was also never the worst. This is typical of statistical fits as they tend to evenly distribute the error. The fit on the 3x3x3 independent data set is rather high. A possible improvement to this model may be to use an appropriately weighted regression (i.e. using the Neugebauer quality factor weights [Neugebauer 1956]) since minimizing errors in XYZ does not directly minimize errors in CIELAB. A table comparing the rankings of the three methods is given below for comparison, the average error as well as the maximum error is given in parentheses next to each model. It would appear from the overall results that the Scaled model would be the best choice to work with in further analysis. Table 9-3Rankings of IBM Models for 3 Data Sets Rank 1st 2nd 3rd Redistribution Peak (0.56, 1.74) Fit (1.20, 6.55) Scaled (1.36, 2.60) 3x3x3 + Random Scaled (3.73, 7.64) Fit (4.06, 7.34) Peak (4.91, 7.93) 17 step Gray Scale Scaled (2.07, 6.23) Fit (2.15, 6.55) Peak (2.71, 8.15)

10 Conclusions

Three displays have been evaluated and compared. The displays tested were a Sony GDM-F500 virtually-flat CRT, a SGI 1600SW flat-panel display, and a 200ppi prototype IBM flat-panel. A summary of the findings follows: The spectral variability of each display was evaluated and found to be quite stable. The temporal characteristics of all three displays was found to be adequate given the four hour warm-up time allowed. The spatial independence of each display was quite good. The SGI especially stood out in this regards, being among the best we have evaluated. The luminance and contrast of the SGI display were quite high, the IBM prototype being a close second. Chromatic constancy was found to be sufficient in each monitor to suggest that an additive model could work. The additivity both in luminance and chromaticity was then evaluated. Both the Sony and SGI display exhibited excellent performance in this regard. The IBM display was found to have a large failure of additivity (~7% in some cases), which may account for the poor performance of the model. The electro-optical transfer function of each display was fit using various methods. This fit was evaluated by estimating the same set of data used in building each model. The performance of each displays model(s) was evaluated using a 3x3x3 and 15 random-color independent target. The Sony and SGI were both very well modeled with maximum errors of 1.1 and 1.8 E*94 respectively. The IBM display was not as well modeled, the best version having maximum errors of 7.6 and an average of 3.7. Some improvements to this model have been suggested and will be evaluated in further reports.

11 References

Gill Bassak, As Fine as the Eye Can See, IBM Research Magazine, 36, (1998). Roy S. Berns, Methods for characterizing CRT Displays, Displays, 16, 173-182 (1996). Roy S. Berns, Ricardo J. Motta, Mark E. Gorzynski, CRT Colorimetry. Part I: Theory and Practice, Color Res. and Appl., 18, 299314 (1993a). Roy S. Berns, Ricardo J. Motta, Mark E. Gorzynski, CRT Colorimetry. Part II: Metrology, Color Res. and Appl., 18, 315325 (1993b). H.E. J. Neugebauer, Quality Factor for Filters Whose Spectral Transmittances are Different from Color Mixture Curves, and Its Application to Color Photography, JOSA, 46, 821824 (1956).