This standard is applicable to various television broadcast receivers (hereinafter referred to as television sets) that conform to the Chinese radio and television standards, and can also be used as a reference for subjective test evaluation of television sets of other radio and television standards. GB/T 9379-1988 Subjective test evaluation method for television broadcast receivers GB/T9379-1988 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
GB/T9379—1988
Subjective tests and assessment for broadcasting television receivers1988-04-15Promulgated
1988-12-01Implementation
Ministry of Electronics Industry of the People's Republic of China
National Standard of the People's Republic of China
Subjective tests and assessment for broadcasting television receiversGB/T9379—1988
This standard applies to various television broadcasting receivers (hereinafter referred to as television sets) that conform to the broadcasting and television standards of my country, and can also be used as a reference for subjective test and evaluation of television sets of other broadcasting and television standards. In order to determine the quality of television sets, objective measurement alone is not enough, so this standard specifies a subjective test and evaluation method. When factories need subjective test evaluation in routine tests and identification tests, the method specified in this standard should be used. In case of disputes over the items related to subjective evaluation in the acceptance test, the method specified in this standard shall prevail. The listening test of the sound quality of television sets shall be carried out in accordance with the method used in GB/T9375 "Listening Test for Radios and Recorders", but in a simplified form.
Subjective test is a method of comparison with reference television sets. This standard refers to IEC569-1977 "Guide to Subjective Test of Television Receivers" 1 Classification
Television sets should be divided into several categories, for example, according to the following characteristics: a. Color or black and white television receivers,
b. Screen size and type,
c. Power supply mode: AC, DC or AC/DC, d. TV set level.
When conducting subjective test evaluation of television sets, it is generally carried out according to the classification. 2 Test room characteristics and test conditions
It is recommended to use a room similar to a family home, and it should meet the following conditions: a. The viewing distance should be as much as possible six times the height of the image. If other distances are used, they should be stated in the test results. b. The horizontal center axis of the TV screen is roughly at the same level as the evaluator's eyes. c. The lighting used in the room should not significantly affect the image quality (about 251x). The intensity of the indoor light shining on the screen should be less than or equal to 0.5cd/m2 when the TV is not working. d. The ratio of the background brightness (behind the TV) to the peak brightness of the image is about 0.1. e. The background sound level (measured by a sound level meter) should be less than or equal to 35dB (A-weighted meter, slow gear). If the same room is used for both viewing and listening, it must meet the requirements of both tests. f. It is recommended that the number of TVs used in a test should not exceed 5 (including the reference TV). When more TVs are to be evaluated, they can be divided into appropriate groups. 8. The TV should be placed and adjusted according to the manufacturer's instructions. h. Indoor climate conditions
Temperature: 18~35℃, preferably 20℃
Approved by the Ministry of Electronics Industry of the People's Republic of China on April 15, 1988 and implemented on December 1, 1988
Relative humidity: 25%~75%
Air pressure: 86106kPa.
GB/T9379—1988
Note: If the performance of subjective test instruments and equipment is not affected and the evaluators do not feel uncomfortable, the climate conditions can be appropriately relaxed. In case of dispute, the provisions of Article h shall prevail.
3 Conditions of evaluators and teams
a: The evaluators should be familiar with the use of various types of TV sets similar to the TV set being tested, have viewing experience, and be able to judge the quality of the TV set.
b. The evaluators should have normal eyesight (glasses can be worn when necessary) and color vision. c. According to different evaluation purposes, the evaluation team may include professionals or non-professionals. Professionals are those who specialize in television technology and those who have specialized knowledge of color applied to television. All other people are considered non-professionals. For tests conducted for consumers, the panel is preferably composed of non-professionals. Even if the panel includes professionals, they are a very small minority. d. The evaluation panel should be composed of men and women in equal proportions as much as possible. e. The group should have people of different age characteristics. It should be mainly middle-aged and young people, and experienced elderly people can also be included. f. The personnel of the evaluation panel (including whether they are professionals, gender, age, occupation and number of people, etc.) should be stated in the evaluation results. 4. Number of evaluations
In order to obtain statistically confident evaluation results, the total number of evaluation personnel is preferably 20 or more, but not less than 7. When there are many people, it can be carried out in batches.
5. Visibility of the TV
In order to avoid any psychological influence, the evaluation team can only see the image of the TV. The cover must be sound-permeable. 6. Reference TV
The reference TV should be selected according to the required image quality and evaluation purpose. A similar television set of the same type or an appropriate prototype may be selected as a reference, and it may also be selected from the television set to be tested. This is used for comparative testing with the television set to be tested. In the case of subjective testing, the performance of the reference television set must be consistent, so that the correctness of a single series of tests can be guaranteed when the same reference television set is used.
The selected reference television set should be stated in the evaluation results. 7 Input signal
The input signal should be a radio frequency signal modulated by a full television signal in accordance with GB1385 "Black and White Television Broadcasting" and GB3174 "Color Television Broadcasting".
All equipment and instruments used for testing and inspection, including monitors, must be of high quality. 8 Characteristics of modulated signals
a. The characteristics of the full television signal should comply with the requirements of GB1385 and GB3174. b. The modulated signal is shown in Table 1.
Test chart
2min')
(black and white and color)
GB/T9379-1988
(including color and black and white TV measurement test charts, color TV standard skin color test charts)Still image
Moving image
Note: 1) The duration can be adjusted appropriately according to the nature of the test and the number of TV sets. Accompanying
Refer to GB/T9375
c. In order to observe the possible mutual influence between the accompanying sound and the image signal, all image modulations should be accompanied by appropriate sound modulation.
9 Image selection
a. In order to make an accurate evaluation, the color, form, details, brightness and contrast of the image should not distract the evaluator. b. The selected program should be convenient for comparative testing between different regions. c. The color and picture structure of the selected image should have a certain degree of sensitivity to different distortions. d. Common colors should be included, such as skin color, sky blue, grass green and red flag color. e. Different average brightness, contrast, different detail richness and different picture composition should be included. For example, indoor, outdoor distant view, medium view, close view, characters, scenery, many details, medium details, few details and complex, simple, bright and dark backgrounds. f. Multiple tones and more saturation levels. 10 Test procedure
10.1 Signal input method
Feed the specified signal to the RF input terminal of each TV through an impedance matching network. Table 2 shows the signal level added to the RF input terminal of the TV. Table 2
Input signal level expressed in useful power 1) Preferred value dB (mW)
Equivalent useful power
Note: 1) One or more signal levels can be selected according to the purpose of subjective test evaluation. 10.2 Tuning
Approximate equivalent signal source electromotive force E
R=3002
R,=75Q
170μv
Tuning is performed on any channel according to GB/T9372 "Measurement Methods for Television Broadcast Receivers" or according to the manufacturer's regulations. 10.3 Adjustment
a: Brightness and contrast: Adjust the brightness and contrast control knobs of the TV according to the TV test pattern so that the white level brightness and black level brightness on the screen are 80~140cd/m2 and 2~3cd/m respectively. If the values ​​required by some TVs being evaluated are different from the above, the selected values ​​and the reasons for their selection should be explained in the test results. b. Saturation and hue: According to the color TV test pattern, adjust the saturation and hue control knobs to obtain the best color reproduction on the screen. c. Clarity (sharpness): If the TV has control knobs such as clarity and sharpness, it should be adjusted according to the relevant test pattern. 3
GB/T9379—1988
d Volume and tone: The volume and tone control related to the accompanying sound effect should be carried out in accordance with the provisions of GB/T9375. When watching and evaluating the image quality, the volume can be adjusted as needed.
10.4 Evaluation
In order to evaluate the performance of the subjects listed in Table 3, all television sets were subjected to subjective tests and evaluations using both black-and-white and color signals. Table 3
Black-and-white television receiver
(6) Definition (sharpness)
(7) Gray-scale reproduction
(8) Geometric distortion and image reproduction rate (stuttering) (9) Image interference
(10) Overall image quality
a. For black-and-white signals
b For color signals
(11) Interference with the accompanying sound
(12) Overall sound quality1)
(13) Overall reproduction quality
Note: 1) Refer to GB/T9375.
11 Working conditions and working rules of the evaluation team (1) Color purity
(2) Convergence
Color television receiver
(3) Overlap of brightness and chromaticity components
(4) Grayscale modulation
(5) Color satisfaction
(6) Clarity (sharpness)
(7) Grayscale reproduction
(8) Geometric distortion and image reproduction rate (toning) ( 9) Image interference
(10) Overall image quality
a. For black and white signals
b. For color signals
(11) For accompaniment
(12) Overall sound quality1)
(13) Overall reproduction quality
Working time: Each test (image, or sound, or image and sound test) should not exceed 10 minutes (see Article 8). This time includes comparative observation of the reference sample. The evaluation team should not be required to carry out the evaluation work continuously for more than 20 minutes. The rest time of the evaluation team should be at least equal to the time they carry out the evaluation work. A working time should not exceed 2 hours, including the evaluation work time and the rest time. When the evaluation team works for the first time, it is recommended to have a 2-hour rehearsal time. At the beginning of each test stage, the test leader should first clearly and briefly introduce the test method, evaluation system, scoring level and the category of the tested TV to the evaluation personnel. The tone should be unbiased and avoid hints that may affect the score assessment. The written description should be sent to each evaluator.
When the evaluation officially begins, the evaluator should independently score the officially reproduced evaluated image and accompanying sound on the score registration card according to the instructions for the relevant scoring levels. During the test, the evaluator's vision and hearing should not be disturbed by the environment and it is easy to concentrate. 12 Power supply voltage
a. AC-powered TV: 220V ± 10%. b. DC-powered TV: powered by batteries, primary batteries or other similar energy sources such as solar cells, thermocouple batteries, etc. c. For TVs used for non-single-type power supplies, the TV should be connected to various types of power supplies for separate tests. d. The power supply conditions used (including category, normal operating voltage, overvoltage, undervoltage, etc.) should be described in the test results. 4
13 Scoring method and data processing
13.1 Scoring method
a. Five-level comparison system
GB/T9379—1988
The comparison system compares the image being evaluated with a reference image and makes a comparative score based on the subjective judgment of the evaluator. The five-level comparison system is graded as follows:
+2: Much better quality than the reference image.
+1: Slightly better quality than the reference image.
0: Same as the reference image.
-1: Slightly worse quality than the reference image.
-2: Much worse quality than the reference image.
b. Five-level quality system
The quality system scores the image being evaluated based on the comprehensive quality of the subjective feeling of the image quality. The five-level quality system is graded as follows:
5 (excellent): The image quality is excellent and very satisfactory. 4 (Good): The image is good and quite satisfactory.
3 (Medium): The image is average and acceptable. 2 (Poor): The image is relatively poor and barely watchable. 1 (Inferior): The image is of poor quality and cannot be watched. c. Five-level damage system
The damage system is to score the image based on the subjective feeling of the degree of damage to the image quality. The five-level damage system is graded as follows:
5: No damage or interference is detected on the image. 4: There is slightly detectable damage or interference on the image, but it is not annoying. 3: There is obvious damage or interference on the image, which is somewhat annoying. 2: The damage or interference on the image is serious and quite annoying. 1: The damage or interference on the image is extremely serious and cannot be watched. Relative or absolute grades are used as needed. 13.2 Data processing
According to the scores obtained by each evaluator according to Table 3, the final score is expressed as the average value P㎡, and the corresponding standard deviation S is given at the same time.
The mean value P㎡ and the standard deviation S should be calculated as follows: Mean value Pm
Standard deviation S=
Where ·P....P. is scored n times.
The confidence level of the evaluation result decreases with the increase of the standard deviation. (Pm—P,)2
.......... (2)
A1 Color purity
GB/T9379—1988
Appendix A
Explanation of relevant terms
(reference)
In the case of a shadow mask tube, if each of the three beams excites only the corresponding color point in an appropriate proportion on the entire screen, then the color purity is good. Color purity errors can cause coloring of black and white images and confuse the colors of color areas. A2 Convergence
The convergence quality depends on the accuracy of the coincidence of the three primary color images. In areas dominated by colorless images, the more clearly the color around the edges is seen, the worse the convergence quality.
A3 Overlap between luminance and chrominance components
The quality of this depends on the time delay difference between the luminance and chrominance signal components. The evaluation of this characteristic requires special care to avoid confusion with other effects that produce false color edges.
A4 Grayscale Tone
The quality of grayscale tone depends on the degree to which the gray gradients reproduced are nearly stable and free of color. A5 Color Satisfaction (under consideration)
The more natural and pleasant the colors look, the more satisfactory the image is considered. A6 Clarity (Sharpness)
Clarity (Sharpness) depends on:
a. The degree to which the details transmitted by the reproduction are close to the maximum capability (resolving power) of the system. b. The boundaries are clear, there are no rough edges around the scene, no white or color edges, no multiple contours and shadows or color smearing (transient response includes ringing, overshoot, smearing, etc.).
c. The degree to which the horizontal scan lines are regularly distributed across the screen; their spacing (interlacing) should be uniform. d. The degree to which the majority of the horizontal scan lines are finely and evenly focused on the screen (focus). A7 Grayscale Reproduction
The degree to which grayscale levels with equal brightness steps extending from black level to white level are correctly reproduced. A8 Geometric Distortion and Image Reproduction Rate (Cooling)a. Geometric distortion is the degree to which the reproduced object differs from its actual shape and relative size. It depends on the degree to which the horizontal and vertical ratios of the scene remain approximately constant when it is displayed in different parts of the screen (linearity). Straight lines in the scene appear curved, wavy or angular in the image. bCooling is the degree to which the transmitted image is contained in the frame width of the television screen. A9 Image Interference
Image interference is irregularities in brightness and/or chromaticity or interference that impairs image stability, or any combination of these. 6
GB/T 9379—1988
a.The most common irregularities of brightness and/or chrominance are: variations in background brightness from top to bottom or from left to right. A slight blur on the left or right side of the screen. Some narrow vertical bands on the left side of the screen.
A wide vertical band across the entire screen.
A gritty image.
A series of narrow horizontal bands across the entire image or a portion of it (venetian blinds). Black horizontal bands in the background (image ripple or hum interference). Horizontal bars related to the rhythm of the volume of music or speech transmitted simultaneously (sound effects on the image, microphonic effects). Dotted or mesh patterns (visibility of beat oscillations of the sound carrier, the color subcarrier, or both). b. The most common disturbances that destabilize the image are: vertical and horizontal jitters across the entire image or a portion of it, wave-like motion in parts of the image that should be stationary, irregular image jumps; bzxZ.net
Horizontal scan line tearing.
A10 Overall picture quality
Overall picture quality is the overall impression of the evaluator on the picture quality after noting the quality of the various picture properties just tested.
A11 Interference with accompanying sound
These interferences are interferences caused by unwanted signals generated in the TV set, or mechanical vibrations of its components. a. The first type of interference is:
Acoustic interference (caused by the power supply voltage and its harmonics); steady-state buzzing of the vertical deflection frequency (internal carrier modulation or vertical deflection buzzing): buzzing of the vertical deflection frequency, the intensity of which varies with the picture content; clicks (caused by internal electrostatic discharge); noise that occurs with changes in picture content, such as noise caused by changes in motion or contrast. b. The second type of interference is:
Noise caused by mechanical vibrations of the vertical deflection components or the power transformer; horizontal frequency howling caused by vibrations of the horizontal output high-voltage transformer or other parts of the deflection circuit; noise caused by other parts.
A12 Overall sound quality
Overall sound quality refers to the overall impression of the evaluator on the sound quality after noting the quality of the various sound performances just tested. Especially for soft music, the key to evaluate is the clarity of the sound. A13 Overall reproduction quality
Overall reproduction quality refers to the overall quality impression of the receiver performance when the evaluator pays attention to the quality of the various image and sound performances just tested before the evaluation.
Evaluator's seat
Tested machine number
Evaluation items
Overlap of brightness and chrominance components
Grayscale modulation
Color satisfaction
Clearance (sharpness)
Grayscale reproduction
Geometric distortion and image
Reproduction rate (stuttering)
Image interference
Total image quality:
a. For black and white signal
b. For color signal
Interference to the accompanying sound
Total accompanying sound quality
Total reproduction quality
Total score
+2: Much better than the reference image quality.
+1: Slightly better than the reference image quality.
0: Same as the reference image.
GB/T9379—1988
Appendix B
Relative single-item scoring registration card
(reference)
Date:
Education level
Five-level comparison system
-1: slightly worse than the reference image quality.
—2: much worse than the reference image quality.
①Evaluate black-and-white TVs from item 6. Note:
②Agreement level is indicated by “”.
Reference model number
Current job position
Evaluator's seat
Tested machine number
Evaluation level
Evaluation items
Overlap of brightness and chromaticity components
Grayscale adjustment
Color satisfaction
Clarity (sharpness)
Grayscale reproduction
Geometric distortion and image
Reproduction rate (toning)
Image interference
Total image quality:
a. For black and white signals
b, for color signals
Interference with accompanying sound
Total accompanying sound quality
Total reproduction quality
Total score
GB/T9379—1988
Appendix C
Absolute single-item scoring registration card
(reference)
Date:
Five-level quality system
5 (Excellent): Excellent image quality, very satisfactory. 4 (Good): Good image, relatively satisfactory.
3 (Medium): Average image, acceptable.
2 (Poor): Poor image, barely watchable. 1 (Inferior): Poor image, unwatchable. Note: ① For black and white TVs, start the evaluation from item 6. ② The level of agreement is indicated by "V".
Additional Notes:
Educational Level
Current Job Position
Five-Level Damage System
5: No damage or interference is noticeable on the image. 5
4: Slightly noticeable damage or interference on the image, but not annoying. 3: Clearly noticeable damage or interference on the image, somewhat annoying. 2: Severe damage or interference on the image, annoying. 1: Extremely severe damage or interference on the image, unwatchable. This standard was drafted by the Third Research Institute of the Ministry of Electronics Industry. 9For color signals
Interference with accompanying sound
Total accompanying sound quality
Total reproduction quality
Total score
+2: Much better than the reference image quality.
+1: Slightly better than the reference image quality.
0: Same as the reference image.
GB/T9379—1988
Appendix B
Relative single-item scoring registration card
(reference)
Date:
Education level
Five-level comparison system
-1: Slightly worse than the reference image quality.
—2: Much worse than the reference image quality.
①Evaluate black-and-white TVs from item 6. Note:
②The level of agreement is indicated by “”.
Reference model number
Current job position
Evaluator's seat
Tested machine number
Evaluation level
Evaluation items
Overlap of brightness and chromaticity components
Grayscale adjustment
Color satisfaction
Clarity (sharpness)
Grayscale reproduction
Geometric distortion and image
Reproduction rate (toning)
Image interference
Total image quality:
a. For black and white signals
b, for color signals
Interference with accompanying sound
Total accompanying sound quality
Total reproduction quality
Total score
GB/T9379—1988
Appendix C
Absolute single-item scoring registration card
(reference)
Date:
Five-level quality system
5 (Excellent): Excellent image quality, very satisfactory. 4 (Good): Good image, relatively satisfactory.
3 (Medium): Average image, acceptable.
2 (Poor): Poor image, barely watchable. 1 (Inferior): Poor image, unwatchable. Note: ① For black and white TVs, start the evaluation from item 6. ② The level of agreement is indicated by "V".
Additional Notes:
Educational Level
Current Job Position
Five-Level Damage System
5: No damage or interference is noticeable on the image. 5
4: Slightly noticeable damage or interference on the image, but not annoying. 3: Clearly noticeable damage or interference on the image, somewhat annoying. 2: Severe damage or interference on the image, annoying. 1: Extremely severe damage or interference on the image, unwatchable. This standard was drafted by the Third Research Institute of the Ministry of Electronics Industry. 9For color signals
Interference with accompanying sound
Total accompanying sound quality
Total reproduction quality
Total score
+2: Much better than the reference image quality.
+1: Slightly better than the reference image quality.
0: Same as the reference image.
GB/T9379—1988
Appendix B
Relative single-item scoring registration card
(reference)
Date:
Education level
Five-level comparison system
-1: Slightly worse than the reference image quality.
—2: Much worse than the reference image quality.
①Evaluate black-and-white TVs from item 6. Note:
②The level of agreement is indicated by “”.
Reference model number
Current job position
Evaluator's seat
Tested machine number
Evaluation level
Evaluation items
Overlap of brightness and chromaticity components
Grayscale adjustment
Color satisfaction
Clarity (sharpness)
Grayscale reproduction
Geometric distortion and image
Reproduction rate (toning)
Image interference
Total image quality:
a. For black and white signals
b, for color signals
Interference with accompanying sound
Total accompanying sound quality
Total reproduction quality
Total score
GB/T9379—1988
Appendix C
Absolute single-item scoring registration card
(reference)
Date:
Five-level quality system
5 (Excellent): Excellent image quality, very satisfactory. 4 (Good): Good image, relatively satisfactory.
3 (Medium): Average image, acceptable.
2 (Poor): Poor image, barely watchable. 1 (Inferior): Poor image, unwatchable. Note: ① For black and white TVs, start the evaluation from item 6. ② The level of agreement is indicated by "V".
Additional Notes:
Educational Level
Current Job Position
Five-Level Damage System
5: No damage or interference is noticeable on the image. 5
4: Slightly noticeable damage or interference on the image, but not annoying. 3: Clearly noticeable damage or interference on the image, somewhat annoying. 2: Severe damage or interference on the image, annoying. 1: Extremely severe damage or interference on the image, unwatchable. This standard was drafted by the Third Research Institute of the Ministry of Electronics Industry. 9
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