TV pick-up systems Europe:Europe: –25 full-frames/sec –625 lines Pick-up systems:Pick-up systems: –(Orthicon tube family –Vidicon - Plumbicon) –CCD : optoel. transformation, integration, read-out

Typical CCD Sensor 600 lines600 lines 800 pixels / line800 pixels / line 6,6 mm x 8,8 mm surface6,6 mm x 8,8 mm surface 1, 2 and 3 CCD colour camera pick-up systems1, 2 and 3 CCD colour camera pick-up systems –mosaic filters –V( ) + colour opponent –RGB systems

TV camera with three CCDs

Transmission of the tree channels

Signals for TV transmisssion Signals produced by camera:Signals produced by camera:

White balance For  ( ) = 1: thus signals normalised colour mixture curves:

CCD camera responsivity

EBU primaries

Signal processing in a TV Camera

Electronic matrix

Matrixed colour matching functions

Colour rendering with and without matrixing Original chromaticity:Original chromaticity: x: without matrixx: without matrix +: with matrix+: with matrix

Gamma correction Characteristics of a CRT tube:Characteristics of a CRT tube: –F: normalised tristimulus value –E’: normalised input quantity –s: stray light –h: offset –  : approx. 2,2, thus in camera:  =,45

Gamma correction

Corrections in camera Gamma balance in camera: Nonlinear amplitude correction: – –80 % % input range corrected to 80 % % output range

Clamping & Knee in characteristics: Method for getting highlights

Direct connenction between camera and receiver Camera:Camera: –3 receptors –matrixing –clamping –gamma balance Receiver:Receiver: –RGB signals

Luminance - chrominance Luminance: Luminance: – before gamma balance Chrominance signals: Chrominance signals: – no luminance information: zero for achromatics:

Luminance - chrominance Luminance from  distorted signal: Luminance from  distorted signal: –based on NTSC primaries and not on EBU –thus luminance signal depends on chroma Colour difference signals:Colour difference signals:

EBU colour solid in Y - Chrominance Space

Chrominance signals of surface colours

Chrominance signals Luminance signal: 0< E Y <700 mVLuminance signal: 0< E Y <700 mV Chrominance signals:Chrominance signals: -350 mV <...<+350 mV Inverse matrix in receiverInverse matrix in receiver

Signals in TV transmission

Importance of component signals CCIR 601 standard:CCIR 601 standard: –576 active lines –720 pixels per line »for 25 frames/s: 31, pixel/s »with 8 bits/colour: 248, bit/s –Gamma pre-correction - L* similarity »helps to decrease number of quanta steps »smaller bandwidth in chrominance signals »differences visualy equidistant

Comparing  and brightness

The composit signal In PAL, SECAM, NTSC bandwidth = to black & white transmisssion signalIn PAL, SECAM, NTSC bandwidth = to black & white transmisssion signal 1 step: Component signals: bandwidth of chrominance signals approx. 1/4 of lum.signal1 step: Component signals: bandwidth of chrominance signals approx. 1/4 of lum.signal 2 step: modulation of chrom.signal onto colour carrier (PAL: 4,43 MHz), chrominance + phase2 step: modulation of chrom.signal onto colour carrier (PAL: 4,43 MHz), chrominance + phase 3 step: Modulated colour carrier added to Lum. signal3 step: Modulated colour carrier added to Lum. signal

Y

One line of a MAC signal Multiplexed analog components

A possible TV system