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1、 CEA Standard Consumer Camcorder or Video Camera Low Light Performance CEA-639 September 2003 NOTICE CEA Standards, Bulletins and other technical publications are designed to serve the public interest through eliminating misunderstandings between manufacturers and purchasers, facilitating interchang
2、eability and improvement of products, and assisting the purchaser in selecting and obtaining with minimum delay the proper product for his particular need. Existence of such Standards, Bulletins and other technical publications shall not in any respect preclude any member or nonmember of CEA from ma
3、nufacturing or selling products not conforming to such Standards, Bulletins or other technical publications, nor shall the existence of such Standards, Bulletins and other technical publications preclude their voluntary use by those other than CEA members, whether the standard is to be used either d
4、omestically or internationally. Standards, Bulletins and other technical publications are adopted by CEA in accordance with the American National Standards Institute (ANSI) patent policy. By such action, CEA does not assume any liability to any patent owner, nor does it assume any obligation whateve
5、r to parties adopting the Standard, Bulletin or other technical publication. This CEA Standard is considered to have International Standardization implication, but the International Electrotechnical Commission activity has not progressed to the point where a valid comparison between the CEA Standard
6、 and the IEC document can be made. This Standard does not purport to address all safety problems associated with its use or all applicable regulatory requirements. It is the responsibility of the user of this Standard to establish appropriate safety and health practices and to determine the applicab
7、ility of regulatory limitations before its use. (From Project Number 2056, formulated under the cognizance of the CEA R4.2 Recording using a visual method or a measured method. Visual Method: At full bright conditions, properly aim the camera at the EIA resolution chart. Connect the camera video out
8、put to the high resolution monitor input. Visually determine the limiting resolution (number of TV lines). Decrease the illumination to the low light level determined in step 1. Again note the limiting resolution. The minimum acceptable resolution at low light is 70% of the value at full bright. Mea
9、sured Method: Resolution is first checked under normal lighting conditions. A) Set the camcorder to the camera EE mode and shoot a resolution (monoscope) pattern at standard picture frame. B) The output camera video should be Y/C separated (using a VCR or Sony Jig) and the Y signal fed through a lin
10、e select waveform monitor, then on to a TV monitor. C) Scroll down the center vertical wedge of the resolution (monoscope) pattern using the line select function of the waveform monitor. Do this until the depth of modulation (of the wedge) is 20% of full black to peak white level. Take note of this
11、resolution value on the resolution (monoscope) chart, this will be the maximum resolution point. Note: This value is not the maximum resolution. It is actually 70% of the actual resolution. Using this point makes measurements easier. D) Set the light level to the low light condition determined in th
12、e luminance level test. E) Measure to the 20% modulation point using the procedure stated in step C. Note the value. F) The resolution value under low light conditions should be at least 70% of the resolution under normal lighting conditions. 5 -,-,- CEA-639 4.5 Measurement Summary If all of the abo
13、ve listed performance criteria are met, then the specified low light sensitivity rating for the camcorder shall be the low light illumination level determined in test 1. This value is expressed in lux. If the camcorder under test does not meet all of the minimum performance levels specified in tests
14、 3, 4, and 5, then the illumination level should be increased for the measurement in which the minimum specified level was not obtained. When a satisfactory measurement result is obtained, the new illumination level shall be noted. All tests should then be performed again to verify that each test wi
15、ll meet the minimum performance level for the new illumination level. 6 -,-,- CEA-639 Appendix 1 Measurement Worksheet Complete this sheet as each measurement is made. Measurement Value 1) Luminance level _ Lux Perform the following tests at the illumination level determined in step 1. 2) Black Leve
16、l _ IRE Spec limit: 7 3 IRE 3) Luminance Signal to Noise _ dB Spec limit 17 dB minimum 4) Chroma level _ % 25% minimum of full bright level 5) Resolution _ % 70% minimum of full bright resolution If the specified limits are met in all of the above tests, the low light sensitivity rating of the camer
17、a is the illumination level determined in step 1. Low light sensitivity rating for camera under test: _ Lux 7 -,-,- CEA-639 Appendix 2 Suggested Lighting Method For Camcorder Low Light Measurements 1) Illumination field flatness on chart: Brightness at chart corners shall be within 10% of brightness
18、 at chart center 2) Color temperature of light source to be 3100 200 Kelvin throughout complete required illumination range The lighting diagram indicated above can provide a simple, cost-effective and easy-to-use light source. The light sources can be constructed as follows: 1) Obtain two (2) camco
19、rder accessory lights (Ambico V-0880 or equivalent). Either a twenty or ten watt bulb can be used. The light source shall have a color temperature within the range of 3100 200 k. 2) Obtain two (2) ring adapters that can be glued or otherwise attached to the outer diameter of the accessory light lens
20、. The large size of the ring adapter should be of a diameter that is a common filter diameter. Attach the ring adapters to the outer diameter of the light lens. 3) Obtain four (4) sets of linear polarizing filters with a diameter equal to the larger diameter of the ring adapter. Each set consists of
21、 two polarizing filters that can be rotated relative to each other. When two sets are attached together, rotation of one of the outer rings provides a method by which the illumination can be controlled. The filters should also be chosen so that they provide almost complete “black out” at the maximum
22、 level of filtering. They should also not change color temperature to limits outside the specified range. 8 -,-,- CEA-639 Appendix 2 Cont 4) Attach the two sets of polarizing filters to the ring adapters. 5) Check the color temperature of the light source throughout the entire required range of illu
23、mination. It should be within the spec of 3100 200 k. The color temperature should be verified using a chroma meter. 6) The lights should be positioned as indicated in the diagram on the previous page. Since lighting conditions may vary from set up to set up, the distances indicated are approximate.
24、 The goal of light positioning is to achieve both adequate illumination levels and uniform illumination of the chart. 9 CEA-639 Appendix 3 If the 11”x14” grey card is not available, then it can be constructed as follows. Use the following paint: Rosco 5735 TV White Rosco 5740 TV Black Paint can be o
25、rdered from Rosco, Port Chester, NY (914) 937-1300 For 18% reflectance, mix 78% white to 22% black. Apply to 11”x14” card. When surface is dry, verify reflectance with an accurate reflectance meter. 10 -,-,- CEA-639 Appendix 4 ADVERTISING YOUR PRODUCT USING THE CEA LOW LIGHT STANDARD Wording to be u
26、sed to indicate compliance with the standard. The following words shall be used on product cartons, brochure sheets and in general advertising: “Measured by CEA method” or “Measured using CEA standard” For example: 5 Lux low light sensitivity. Measured by CEA method. For product technical specificat
27、ions the following can be used: Measured using CEA-639 standard. 11 -,-,- CEA Document Improvement Proposal If in the review or use of this document, a potential change is made evident for safety, health or technical reasons, please fill in the appropriate information below and email, mail or fax to
28、: Consumer Electronics Association Technology & Standards Department 2500 Wilson Blvd. Arlington, VA 22201 FAX: 703 907-7693 standardsce.org Document No. Document Title: Submitters Name: Telephone No.: Submitters Company: FAX No.: e-mail: Address: Urgency of Change: Immediate: At next revision: Problem Area: a. Clause Number and/or Drawing: b. Recommended Changes: c. Reason/Rationale for Recommendation: Additional Remarks: Signature: Date: FOR CEA USE ONLY Responsible Committee: Chairman: Date comments forwarded to Committee Chairman: -,-,- -,-,-