Medical Video 1 rev 2016-02-04 this is now slide 1 things to do (check off when complete): do not print it to pdf add revision date to cover page remove triangles create list for pages to print in the handout
2-3,7-13,16-18,24-26,29-33,36-40,43,45-46,48-52,54,58,60-64,71-73,78 add captions for photo slides incorporate notes taken during presentation add Key Points page 3
(cover page is an animation!) slide 29; corrected additive (light) color vs subtractive (ink, pigment) color
I should add a slide about perception of color, rods & cones, wiki: photoreceptor cells, Guy Deutscher’s
Through the Language Glass, etc. But not today.
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© D. J. McMahon 150512 rev cewood 2016-02-04

Key Points
Medical Video:
- Know the principle of how a CRT works
- Know the hazards of working with CRT circuitry
- Know the differences between the sweep lines and frequencies for NTSC and PAL
- Know how an image is formed by the fields and frame of the NTSC format
- Know the standard color temperature for medical video displays
- Understand the three most commonly used analog video formats: composite, S-video, and component; and why one is better than another
- Recognize three digital signal connectors: SDI, HDMI, & DVI

1923 - First patent on a TV camera tube
1927 - First long distance TV transmission, New York to Wash D.C.
1928 - First TV station licensed by the FCC
1930 - First TV commercial ad
1936 - 200 TV sets in use world-wide
1939 TV demonstrated at NY World’s Fair
1941 - FCC approves the standard for black & white TV
1948 - Cable TV introduced in Pennsylvania
1950 - FCC approves the first standard for color TV

Basic Cathode Ray Tube (CRT)

Creating the raster on a CRT -

Interlacing:

Horizontal and vertical synchronization signals: tell the trace when to blank and restart.

(National Television Standards Committee)
Upper left to lower right,
1 st field: 262½ lines in 1/60 th second
2 nd field: 262½ lines interlaced with first field
Total = 525 lines in 1/30 th second
= 1 frame
Horizontal sweep frequency: 525 lines x 30 lines/sec
= 15,750 Hz

Black & white video “step” test pattern on a CRT :

Black & white video “step” pattern as seen on an o-scope :

Video Formats in use Worldwide:
NTSC : National Television Standards Committee
> 525 lines, 60 Hz, color subcarrier at 3.58MHz
PAL : Phase-Alternating Line
> 625 lines, 50 Hz, color subcarrier at 4.43 MHz
SECAM : Systeme Electronique Couleur Avec Memoire
(Electronic Color System with Memory)
> 625 lines, 50 Hz, colors sent in sequence with a time delay
There are about twelve variants of all three of these standards, differing in lines per frame, sweep frequency, and color formatting.

Analog Television Standards of the World
Green = NTSC Yellow = PAL Orange = SECAM

Beware the NTSC/PAL switch !

Generic 6.0 MHz television channel:

For Television Channel 5:
77.25
MHz
78.5
MHz
82.0795
MHz
83.0
MHz

More information than you wanted:
Detail of the picture carrier with color:

More information than you wanted:
Detail of the Color Burst:
R, G, B, and sync signal(s) apart

Any color is defined in three parameters:
Hue: specific wavelength of a color
Saturation: amount of additional wavelengths in a color
Brightness: amplitude of the wavelengths in a color
+
-
-
+

“Color Temperature” :
The color temperature of a light source is determined by comparison to a ‘black-body radiator’. The temperature at which the blackbody radiator matches the color of the light source is that source's “color temperature”.
Any light source has a specific color temperature: room lights, car headlights, video displays, etc.

More information than you wanted:
Black Body : a theoretical object that absorbs all incident light energy, at any frequency or angle of incidence.
A black body emits light based only on its temperature in ° Kelvin.
(Kelvin = centigrade +273)

The ideal color temperature for video displays is usually set at
6500 °K, but most displays can be adjusted to other values.

Saturation:
CIE Standard “Color Space” Chart, 1931
6500 ° K

R-G-B is used in video Colors are additive
( C-M-Y-K is used in ink & pigment Colors are subtractive)
K
Video & Light Dye, Ink & Pigment

R + G + B = white
If red is missing, image is light blue (cyan).
If green is missing, image is purple (magenta).
If blue is missing, image is yellow (yellow).

Y = luminance (brightness signal)
C = chrominance (color signal)
R = red
G = green
B = blue
P b
P r
= difference between Y and Blue
= difference between Y and Red

Analog Video Signal Formats:
1) Composite (good):
Luminance Y, Chrominance C, and synchronization (“sync”), all superimposed on one signal.
“Sync” are the horizontal and vertical sweep signals.
Yellow connector is the composite video signal.
Red and white connectors are the R and L audio signals.

Analog Video Signal Formats:
2) Y/C (“S-Video”) (better)
- Luminance (Y) and Chrominance (C) separated
- 4-wire cable: 2 for each component (separate grounds)
Chrominance Luminance
(male connector)
Female connector
2
3
4
Pin Name
1 GND
Function
Ground for Y
GND
Y
C
Ground for C
Luminance
Chrominance

Use caution with DIN-type S-video connectors

Composite: Y/C (S-video):
In S-video, Luminance and chrominance are separated, and don’t interfere with each other.

Analog Video Signal Formats:
3) Component (R-G-B) (best)
- Red, Green, Blue, and sync signals are separate.
- may be 3, 4, or 5 shielded wires:
3 wires: R, G, B (with syncs on the Green signal (“SOG”))
4 wires: R, G, B, and horizontal sync (white wire)
5 wires: R, G, B, and horizontal and vertical syncs

VGA is an implementation of Analog Component (R-G-B) (best)
5 (signal) wires: R, G, B, and horizontal and vertical syncs
Pin 1
Pin 2
Pin 3
Pin 4
RED Red video
GREEN Green video
BLUE Blue video
ID2/RES formerly Monitor ID bit 2,
Pin 5
Pin 6
Pin 7
Pin 8
Pin 9 reserved since E-DDC
GND Ground (HSync)
RED_RTN Red return
GREEN_RTN Green return
BLUE_RTN Blue return
KEY/PWR formerly key, now +5V DC
Pin 10 GND Ground (VSync, DDC)
Pin 11 ID0/RES formerly Monitor ID bit 0, reserved since E-DDC
Pin 12 ID1/SDA formerly Monitor ID bit 1,
I²C data since DDC2
Pin 13 HSync Horizontal sync
Pin 14 VSync Vertical sync
Pin 15 ID3/SCL formerly Monitor ID bit 3,
I²C clock since DDC

4) YP
B
P
R
(“Yipper”)
- Y, P
B
, and P
R
(even bester ) signals are separate as in R-G-B
- Uses less bandwidth, and image is crisper
- Can handle higher resolutions than other analogs

More information than you wanted:
YP
B
P
R is converted from the RGB video signal by splitting it into three components:
Y carries the luminance (brightness) and synchronization
(sync) information:
Y = 0.2126 R + 0.7152 G + 0.0722 B
(With color, Y still represents intensity but it is a composite of R. G, and B.)
P
B carries the difference between blue and luma (B − Y).
P
R carries the difference between red and luma (R − Y).

Generic analog TV or monitor with CRT display:

Three analog inputs into one monitor:

Any color can be assigned a triplet of R-G-B digital values:
(0, 0, 0) is black
(255, 255, 255) is white
(255, 0, 0) is red
(0, 255, 0) is green
(0, 0, 255) is blue
(255, 255, 0) is yellow
(0, 255, 255) is cyan
(255, 0, 255) is magenta
(this defines 2 24 or ~ 16 million colors) worth looking at: https://en.wikipedia.org/wiki/Lists_of_colors

Various colors and their digital value assignments:

How is digital video displayed ?
Digital displays consist of picture elements, or “pixels”.
Digital displays light-up all the screen pixels in one frame at a time.
Each pixel has one color.
The color depth is typically 24 bits per pixel. (More bits = better color.)
The frame rate is the number of frames displayed per second.
The bit rate is the total number of bits being moved per second.
Example:
If a display has 640 x 480 pixels, there are 307,200 pixels.
If there are 24 bits per color, we have 307,200 x 24 = 7,372,800 bits (7.37 Mbits)
If there are 25 frames per second, we have 7.37 x 25 = 184.25 Mbits/sec
If we have a 10-minute (600 sec) video presentation, the video size is
184.25 x 600 = 110,550 Mbits or 13,819 MBytes or 13.819 GBytes

Resolution - the amount of information per unit area

Four different digital television standards
DVB-T: Digital Video Broadcasting, Terrestrial
ATSC: Advanced Television Systems Committee
ISDB-T: Integrated Service Digital Broadcast, Terrestrial
DMB-T/H: Digital Multimedia Broadcast - Terrestrial/Handheld

1) Serial Digital Interface (SDI) –
- 270 MBits/Second digital stream
- Single conductor, but must be low-loss coaxial cable
- Uses a BNC connector

2) High Definition Media Interface (HDMI) –
- multiple scan rates
- multi-conductor, 10.2 Gbits / Second
- common in consumer video, but not often used in medical

3) Digital Visual Interface (DVI) –
- RGB data, clock, channel formatting, & audio
- 3.96 Gbits/s

Female DVI-I socket from the front:
Pin 1
TMDS data 2−Digital red− (link 1)
Pin 2 TMDS data 2+Digital red+ (link 1)
Pin 3 TMDS data 2/4 shield
Pin 4 TMDS data 4−Digital green− (link 2)
Pin 5 TMDS data 4+Digital green+ (link 2)
Pin 6 DDC clock
Pin 15 GroundReturn for pin 14 and analog sync
Pin 16 Hot plug detect
Pin 17 TMDS data 0−Digital blue−(link 1) & dig sync
Pin 18 TMDS data 0+Digital blue+(link 1) & dig sync
Pin 7 DDC data
Pin 8 Analog vertical sync
Pin 9 TMDS data 1−Digital green− (link 1)
Pin 10 TMDS data 1+Digital green+ (link 1)
Pin 11 TMDS data 1/3 shield
Pin 12
Pin 13
TMDS data 3-
Digital blue− (link 2)
TMDS data 3+Digital blue+ (link 2)
Pin 19 TMDS data 0/5 shield
Pin 20
TMDS data 5−Digital red− (link 2)
Pin 21
Pin 22
Pin 23
Pin 24
C1
TMDS data 5+Digital red+ (link 2)
TMDS clock shield
TMDS clock+Digital clock+ (links 1 and 2)
TMDS clock−Digital clock− (links 1 and 2)
Analog red
C2 Analog green
C3 Analog blue
Pin 14 +5 VPower for monitor when in standby C4 Analog horizontal sync
C5 Analog groundReturn for R, G, and B signals

- Cathode Ray Tube (CRT) past gold standard, but going extinct
- Electroluminescent (EL) light-emitting, high current draw
- Liquid Crystal Display (LCD) impractical unless back-lit, but efficient
- Plasma Displays better angle of view, run hot

Interlaced Scan vs Progressive Scan -
Interlaced: Each frame is ‘painted’ in two fields which use odd and even-numbered lines then..
First Field Second Field
Two fields = one Frame
Progressive: Entire frame is ‘painted’ in one sequence of lines, top left to bottom right.
(There are no ‘fields’.)

Resolution: 720p vs 1080p
Most medical video is in 1080p

Liquid Crystal Technology (LCD) display:

: Cold Cathode Fluorescent Tubes for back-lighting LCD displays

CCFLs require a high voltage (60 – 90 Vac), produced by an inverter

CCFL inverter board in a medical monitor

Video Test Patterns

Society of Motion Picture & Television Engineers (SMPTE)
Early standard test pattern

SMPTE Standard Test Pattern RP 219:2002

SMPTE resolution test pattern
SMPTE Gamma test pattern.
Gamma ( γ) is a correction made to the luminance level to adjust for human vision.

> System Power Supply may be non-isolated
> High Voltage Power Supply develops very high voltages which can reside for hours after power is off
> The CRT tough, but can crack or implode
Safe Practices:
> Use an isolation transformer on the device
> Discharge large capacitors
- use a high wattage resistor,100 ohms/volt of capacitor value
- ( do NOT use a screwdriver ! )
> Stay away from the CRT anode wire, the HV supply, and the PC board on the neck of the CRT

Humble beginnings: