1、BRITISH STANDARD Video cameras (PAL/SECmSC) - Methods of measurement Part 1. Non-broadcast single-sensor cameras The European Standard EN 61146-1 : 1996 hag the status of a Britjsh Standard ICs 33.160.40 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW i1146-1: 1997 1994 EC 114
2、6-1 : BS EN 61146-1 : 1997 Amd. No. This British Standard, hawig been prepared under the direction of the Elechtechnicai Sector Board, was published under the authority of the standards Board and comes into effect on 15 March 1997 O BSI 1997 Date Textaffected Committees responsible for this British
3、Standard The preparation of this British Standaxd was entrusted by Technical Committee EPU100, Audio, video and multimedia systems and equipment, to Subcommittee EPUlL3, Equipment and systems in the field of audio, video and audiovisual engineering, upon which the following bodies were represented A
4、ssociation of British Theatre Technicians Audio Engineering Society British Broadcasting Corporation British Educational Suppliers Association British Federation of Audio British Radio and Electronic Equipment Manufkturers Association British Telecommunications plc Federation of the Electronics indu
5、stry Independent Television Association (lNA) Institute of Sound and Communication Engineers Institution of Electrical Engineers International Association of Broadcasting Manufacturem Professional Lighting and Sound Association Royal Institute of British Architeds Royal National Institute for Deaf P
6、eople Society of Cable Television Engineers The foiiowing BSI references relate to the work on this standard: Committee reference EPU100B Draft for comment 89/25912 DC ISBN O 680 26931 O STD-BSI BS EN bLLVb-L-ENGL 1777 Lb24bb7 0578q77 T50 BS EN 61146-1 : 1997 O BSI 1997 Contents Commim responsible N
7、ationai foreword page Inside front cover ii Foreword Text of EN 611461 2 3 i STD-BSI BS EN bLLqb-1-ENGL 1797 Lb24bb7 0598500 572 BS EN 61146-1 : 1997 National foreword This British Standard has been prepared by Subcommittee EPLlOOB, and is the English ianguage version of EN 6114G1: 1996 Video camera
8、s (T“EC.TSC) Methods of measurement Part 1. Nombroadcast Lo is the luminance of the TV display screen; K is the constant (gain of the camera amplifier); La is the luminance signal at the output of the imager. The overall characteristics of the analyser plus the electro-optic converter will be: where
9、 A m The result mL, shows that the proportionality condition is satisfactory to obtain a correct colour reproduc- tion (see figures 6b, 6c and 6d). is the constant (gain of the TV set amplifier); is the phosphor dot brightness efficiency. 9.2 Method of measurement a) The equipment arrangement shall
10、be as shown in figure 6a. b) The test chart shall be a grey-scale chart. The reflectance of each area from black to white shall vary according to a curve having a gamma of 2,2 (see figure 6c). c) The conditions of shooting shall be those mentioned in 3.3. d) For SECAM, see 7.2, item c). e) The outpu
11、t signal shall be measured by an oscilloscope. If the camera has a gamma of 0,45 (that is the inverse of the grey scale 2,2), the video output signal represents a grey scale having a gamma of 1; this means that the amplitude of the steps related to the black level are in equal increments (see figure
12、s 6d and se). 1) The amplitude Y) of each step n of the output signal, that is from the level at the step n=3 to the level at the step n-10, shall be measured (see figure 6e). g) The reference level Vref shall be the amplitude from blanking level to white level (see figure 6e). However, step V,(O) m
13、ay be taken as reference; this should be reported with the results of measurement. - - STDoBSI BS EN b334b-I-ENGL 3777 = Lb24bb7 0578523 227 = Page 21 EN 61146-1 : 1996 h) The gamma error shall be calculated as the percentage NL (n) of the deviation of the level at each Vo(n). from the theoretical l
14、evel V,(n) of the corresponding step. The errors shall be calculated from step n=3 to step n=lO, as shown in the following formula: where V,(n) = V,n/lO for n=3 to n=10 NL(n) = (Vo(n) - V,(n) 1 Vt(n) x 100 (“/o) 9.3 Presentation of results The results shall be reported in a table showing the number
15、n of each step, and the gamma error in percentage for the two references, as follows: a) blanking level; b) step Vo(0). I -1 I cc- I Ci: = 3100 K I II Input terminated by 75 0 input not terminated Tes ohar No. 1 Und.rsoan adour ,TV monitor Grey-scale pattern (reflective type) - Gamma: 2.2 - Reflecta
16、nce (white area): 89.9 X Figure 6a - Equipment arrangement and test chart Figure 6 - Luminance gamma characteristics STD-BSI BS EN bllYb-l-ENGL 1977 Zb24bb7 0578523 OTT Page 23 EN 61146-1 : 1996 Output signal VA 0.7 l-:p 0.4 - - I/ r=0.45 I I Illumination I O - - Ix Figure 6b - Camera Luminance &/m2
17、 4 Output signal 4 7 - 2.2 V Figure 6c - Cathode ray lube illumination O - Ix Figure 6d - Camera output signal * Ln * Figure 6e - Video output signal Figure 6 - Luminance gamma characteristics (concluded) STD.BSI BS EN bLLYb-L-ENGL 1997 m Lb24bb7 057852Y T3b m Page 24 EN 61146-1 : 1996 10 Cumlnance
18、white clipping and COmpreSsiOn rate 10.1 Characteristics to be specified The white clipping level of the luminance signal is the level at which the white saturation appears. This level is compared to the rated reference luminance signal, and expressed in per cent. The compression rate is defined as
19、the maximum subject illumination for which details can be distinguished from the next lower illumination level below the white saturation level. 10.2 Method of measurement a) The equipment arrangement and the grey-scale test chart shall be as shown in figure 7. b) The conditions of shooting shall be
20、 those mentioned in 3.3. c) The output signal from the black level shall be measured by an oscilloscope. d) Adjust the lens zoom ratio in order to increase the angle of view, and thus the output signal amplitude to saturation level, that is until the two steps having the highest reflectivity, the 9t
21、h and 10th steps, of the grey scale just reach the saturation level. e) The white clipping level Vi shall be read from the oscilloscope screen and related to Vref (see 3.4) (100 % = luminance rated level), as shown below: white clipping = ( VW/ Vref) x 1 O0 (%) 1) The compression rate shall be calcu
22、lated using the reflectance of the two steps, one giving 1 O0 YO level, being Lref and the other being the 9th step, L, as shown below: compression rate = (L,/Lref ) x 100 (%) If no level related to each of the grey steps corresponds to the 100 % level, the reflectance of the nearest step or the lin
23、early interpolated reflectance shall be adopted for Lref. 10.3 Presentation of the results The results of the measurements shall be reported in percentage for the two characteristics. STD.BS1 BS EN bllqh-l-ENGL 1797 Lb2Libb9 0598525 972 W Page 26 EN 61146-1 : 1996 Light CT = 3100 K - For SECAM measu
24、rement I I Input terminatd by 75 P Input not Undenaan wlaw TV monitor Groy-roik chut No. 1 (reflochro typo) with bkdt baekgroun Tho area of tho Mad part shall be eight times that d the eontre chart. - Gamma: 22 - Refl.ct.nce of ho eontre white: 89.9 K Figure 7 - Luminance white clipping and compress
25、ion rate Page 26 EN 61146-1 : 1996 11 Luminance dynamic range and contrast range 1 1 .1 Characteristics to be specified a) The dynamic range: the range between the maximum illumination level causing neither blooming nor smear, and the light level corresponding to the minimum signal level limited by
26、the noise in the luminance channel. b) The contrast range: the range between the level of the compression rate in dB and the signal-to-noise ratio in dB of the luminance signal, specified in clauses 10 and 6, respectively. 11.2 Method of measurement a) The equipment arrangement and the test chart sh
27、all be as shown in figure 25. b) The conditions of shooting shall be those mentioned in 3.3. c) The dynamic range of the luminance signal shall be calculated as the sum of the measured. overexposure loD specified in 22.2 or 23.2 and the signal-to-noise ratio S/N specified in 6.2 as shown below: dyna
28、mic = 20 lg loD + luminance S/N (dB) = 20 x D + luminance S/N (dB) where the exponent O, specifying the blooming or the smear shall be the smallest one. d) The contrast range of the luminance signal shall be calculated as the sum of the measured results the compression rate and the signal-to-noise r
29、atio specified in 10.2 and 6.2, respectively, as shown below: contrast range = 20 lg - Lg + luminance S/N (dB) Lref 11.3 Presentation of results The results of the measurement shall be reported in dB for the two parameters. 12 Luminance white non-unlformity 12.1 Characteristic to be specified The de
30、viation of the luminance signal amplitude in the vertical and horizontal direction of the output picture. 12.2 Method of measurement a) The equipment arrangement and the test chart shall be as shown in figure 8a. b) The conditions of shooting shall be-those mentioned in 3.3. The maximum signal amplitude will probably be 30 Yo to 40 Yo below the amplitude of a small area peak white signal. That amplitude is in the order of 0,5 V, depending on the auto iris control system of the camera under test. c) For SECAM, see 7.2). d) The output signal shall be measured by an oscilloscope.
