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Security protection--Face recognition applications--Specifications for acquiring still face images
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Basic data
| Standard ID | GA/T 1324-2017 (GA/T1324-2017) |
| Description (Translated English) | Security protection--Face recognition applications--Specifications for acquiring still face images |
| Sector / Industry | Public Security (Police) Industry Standard (Recommended) |
| Classification of Chinese Standard | A99 |
| Classification of International Standard | 13.310 |
| Word Count Estimation | 22,243 |
| Date of Issue | 2017-10-08 |
| Date of Implementation | 2017-12-01 |
| Issuing agency(ies) | Ministry of Public Security |
Similar standards
GA/T 424| GB 8108| GA 141|GA/T 1324-2017: Security protection--Face recognition applications--Specifications for acquiring still face images
---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Security protection--Face recognition applications--Specifications for acquiring still face images
ICS 13.310
A99
People's Republic of China Public Safety Industry Standard
Face recognition application
Static face image collection specification
2017-10-08 released
2017-12-01 implementation
Issued by the Ministry of Public Security of the People's Republic of China
Table of contents
Foreword Ⅰ
1 Scope 1
2 Normative references 1
3 Terms and definitions 1
4 Collection method and location 1
4.1 Collection method 1
4.2 Collection site 2
5 Collection specification 2
5.1 Face image collection 2
5.2 Device interface 4
5.3 Image requirements 4
Appendix A (informative appendix) Example of taking facial images 6
Appendix B (Normative Appendix) Rules for Photo Reproduction/Scanning 13
Appendix C (informative appendix) Examples of facial image capture 15
Reference 18
Face recognition application
Static face image collection specification
1 Scope
This standard specifies the terms and definitions, collection methods, locations and collection specifications of static facial images.
This standard applies to the construction of static face image collection environment and equipment configuration for face recognition application certificates or identities.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article
Pieces. For undated references, the latest version (including all amendments) applies to this document.
GA 461-2004 Technical requirements for digital photos used in resident ID card preparation
GA/T 156-1996 Rules for the method of flipping photos
GA/T 706-2007 Technical requirements and collection specifications for digital photographs of suspects
GA/T 893-2010 Application terminology of security biometric identification
GA/T 922.2-2011 Security Face Recognition Application System Part 2.Face Image Data
GA/T 1127-2013 General technical requirements for security video surveillance cameras
GA/T 1180-2014 Technical requirements for digital photos of entry and exit documents
GA/T 1326-2017 Security Protection Face Recognition Application Program Interface Specification
3 Terms and definitions
The following terms and definitions defined in GA/T 893-2010 are suitable for this document.
3.1
Static face image stilfaceimage
The front face image acquired when the object is relatively static and actively cooperates.
3.2
Color rendering index
The color rendering ability of the light source to the object.
Note. Taking sunlight as the ideal reference light source, its color rendering index is defined as 100, the color rendering index of incandescent lamps is very close to the color rendering index of sunlight, and the color rendering index of other light sources
All are below 100.The color rendering index is represented by Ra, which is generally 20 to 100.The larger the Ra value, the better the color rendering of the light source and the smaller the average color difference.
3.3
Flash guide number
GN
The relative power value of the flash. Set based on the sensitivity ISO 100.The basic formula is as follows.
GN=D (distance between flash and subject) × F (shooting aperture)
4 Collection method and location
4.1 Collection method
Static face images should be collected in the following two ways.
a) Face image shooting;
b) Photo retake/scan.
4.2 Collection site
The static face image collection should be carried out in special shooting places such as photo studios, photography shops, self-service photo booths, and ID photo collection points.
Use self-service photography equipment or mobile devices to collect in temporary locations.
Refer to Appendix A for the face image shooting rules of the special place, and refer to A.2 for the face image shooting rules of self-service photography equipment.
Refer to A.3 for the rules for taking facial images of mobile devices in temporary locations.
5 Collection specifications
5.1 Face image collection
5.1.1 Face image capture
5.1.1.1 Environment
The environmental requirements are as follows.
a) Location requirements. The dedicated shooting location should be larger than 3m×3m, and the surrounding walls and ground should be white, light gray or black.
If the site is less than 3m×3m, please refer to A.2.2 for the layout of self-service photography equipment and adjust according to the actual situation;
b) Background requirements. The background should be a single color, white or light gray should be selected, and there should be no shadows or any other object images;
c) Lighting requirements. the ambient light is uniform and flicker-free, and the light intensity ranges from.200lx to 3000lx, avoid appearing within the range of the head of the object
Strong backlight, side light or top light will not be affected by outdoor natural light.
5.1.1.2 Equipment
The equipment requirements are as follows.
a) Acquisition equipment.
1) Choose a digital camera or camcorder with an actual pixel of more than 2 million pixels;
2) The digital camera should support connection to a computer for acquisition, support manual setting of aperture and shutter parameters, and have exposure compensation, white balance,
Color temperature, sensitivity (ISO) and other custom parameter setting functions, where the flash is used as the light source, digital cameras
There should be a synchronized hot shoe or a synchronized hot shoe seat on the device to avoid direct use of the built-in flash;
3) The camera should support connection to a computer to capture, support manual setting of aperture and shutter parameters, and have exposure compensation, white balance, color
For temperature and other custom parameter setting functions, a constant light source should be used as a supplementary light source.
b) Lens. Various zoom or fixed-focus lenses equivalent to the focal length of a full-frame camera of 35mm~135mm should be used.
c) Light source.
1) LED flashes with a color temperature of 4500K~6500K, a color rendering index (Ra) not less than 90, and a stepless adjustment function should be used
Light source or constant light source;
2) Use a soft light device (soft box, soft light umbrella or diffuser) to convert the point light source to the surface light source;
3) When external supplementary light source is equipped, the flash light source single lamp flash index (GN) is not less than 24, and the constant light source single lamp power is 30W~
100W, when the self-service photography equipment uses the built-in fill light source, the single lamp flash index (GN) of the flash light source is not less than 15, constant
The power of a single lamp is 12W~50W.
5.1.1.3 Collection object
The requirements for collection objects are as follows.
a) Posture.
1) Sitting posture. The upper body of the collected object is vertical to the horizontal plane of the seat, shoulders are horizontal, and facing the camera;
c) The maximum compression factor of JPEG or JPEG2000 format is not more than 25 times;
d) The image file capacity is between 14Kbit and 240Kbit;
e) The face image with the shoulder meets the front face image requirements of 4.1.1 in GA/T 922.2-2011;
f) The image is clear;
g) No obvious distortion of facial features and facial contours, no obvious shadows;
h) The skin tone is natural and true;
i) No red eyes;
j) Features such as facial scars and birthmarks will not be cosmetically treated;
k) See Appendix C for examples of common quality problems.
5.3.3 Color adjustment
The color of the image can be adjusted appropriately to make it appear natural and true tones. When the image has a serious color cast, the color should not be forcibly adjusted, and the device should be modified
Recapture after white balance.
5.3.4 Brightness processing
The brightness of human face skin color can be adjusted appropriately to make it appear natural and true tones. When the image is seriously underexposed or overexposed, it should not be forced
To adjust the brightness, you should modify the exposure parameters of the device and then re-acquire.
5.3.5 Sharpness processing
The photos collected through facial image capture are not suitable for sharpness processing. When sharpness processing is necessary, the face should not have obvious grains.
The output should be adjusted to the minimum, and occlusion measures should be taken to prevent the light of the built-in flash from being directly projected on the face of the subject;
c) The output is subject to the observation of the monitor or the camera screen, and there should be no light seepage, halo or uneven distribution.
A.1.3 Device settings
When the sensitivity (ISO) is set to 100~400, the shutter speed should be between 1/60s~1/125s, the main light metering should be F4.5, and the auxiliary
The light metering should be F4.0, the integrated light should be F5.6, and the light ratio should be strictly controlled within 0.3.The exposure should be accurate and should not make the
Now underexposed or severely exposed. There should be no large shadows, highlights or spots. If these situations occur, you can adjust the flash output
Or move the lamp position to solve it.
The comprehensive metering of the background light should be F5.6, and the background light should be flattened to make the background uniform and bright, in all the visible range of the camera's viewing frame
There should be no gradients, reflective surfaces or shadows on the inner background.
A.2 An example of face image shooting with self-service photography equipment
A.2.1 Overview
Self-service photography equipment is an unattended self-service face image acquisition facility, which is generally used to collect high-quality face images. Self photography
The equipment is widely used because of its convenience, avoiding the uneasiness of the collection object facing the photographer, and saving space and manpower.
In order to obtain high-quality face images in the limited space of self-service photography equipment, this appendix gives the corresponding light source, camera position and human position
Design rules.
A.2.2 Light source layout
The interior of self-service photography equipment should adopt white or light gray tones to prevent chromatic aberration on the face. It is advisable to use a large light-emitting area to fill light
The lamp makes the internal ambient light more uniform and soft. The background light should be used to cover a larger area (larger than the camera shooting range) and more uniform
Light source. In order to avoid the interference of external light inside the equipment, the inside of the entrance and exit door curtain should be white or light gray with good shading effect
material.
Figure A.3 The front view shows the position of the light source. When the fill light source is a flash light source, the illuminating light source is placed on the top, which can be used as an auxiliary fill light.
It can be used to solve the red-eye problem that may occur under flash conditions. When the fill light source is a constant light source, it can replace the illuminating light source.
Figure A.4 side view shows the corresponding position of each light source and the collection object, and the angle between the fill light source and the optical axis of the camera
degree. The front fill light source is placed on the left and right sides of the collection device, forming an angle of 30°~40° upwards on the line connecting the lens and the collection object. Fill light
The light source is placed on the lower side of the collection device, and the line connecting the light and the collection object downward forms an angle of 55°~65°.
Figure A.5 The top view icon shows the angle between the fill light source and the optical axis of the camera, the left and right sides of the light source and the collection object and the camera's central axis
Form an angle of about 25°~30°.
A.2.3 Position of camera and collection object
The distance between the camera and the collection object is 0.7m~1.0m, as shown in Figure A.6.
The collection subject should sit upright and should not lean forward excessively. The height of the camera is level with the eyes of the collected object, and the reflection in the liquid can be observed through a single-sided mirror.
The image on the crystal screen, or the direct observation of the image in the single-sided mirror, can be adjusted to the height of the object to be collected by adjusting the height of the seat or camera.
Appendix B
(Normative appendix)
Photo retake/scan rules
B.1 Overview
Remake is the process of making original photos into image files.
Scanning is the process of converting face photos of paper or other materials into image files through equipment such as scanners or electronic color separation machines.
In addition to meeting the requirements of the following chapters, the reproduced/scanned photos should also meet the relevant requirements of Chapter 6 of GA/T 156-1996.
B.2 Remake skills
B.2.1 Auxiliary equipment
A professional macro lens can be used to increase the magnification of imaging and re-photographed photos;
You can choose a shutter release, a special supplement light remake frame or a tripod to stabilize the camera or camcorder and improve the clarity of remake photos.
B.2.2 Fix the rephotographed photo
In order to reduce the reflection and deformation of the reproduced work, the reproduced photo should be fixed and flattened on the reproducer or work surface, and the photo should not be rolled up
Or arched.
B.2.3 Remake lighting
It is not advisable to use flash when retaking;
When you choose a special supplementary light remake stand to remake, place two or more lights on each side of the remake stand, so that the intensity of the light source on both sides is equal, and the
The center of the photo is at the same distance and an angle of about 45°;
When choosing an outdoor or indoor environment with plenty of soft natural light, use oblique light instead of direct light.
B.2.4 Remake equipment operation
In order to obtain higher-resolution photos, it is not advisable to use handheld devices to shoot, and it is advisable to use a photo frame or tripod to fix the device;
The optical axis of the lens coincides with the center of the reproduced photo, the photo is located in the middle of the viewfinder, and its plane is perpendicular to the optical axis of the camera lens.
B.2.5 Common parameter setting rules
The setting rules are as follows.
a) Shooting mode. The camera should use manual (M) or aperture priority (A) mode, and the camera should manually set the exposure according to the actual situation
parameter;
b) Picture quality. The pixel should choose the maximum supported by the device, and the picture quality should be the best and fine;
c) Sensitivity. a slower sensitivity (ISO) should be selected, ISO 100 or below;
d) Aperture. A smaller aperture should be selected, F=8 or above;
e) Exposure. If the environment is dark, the exposure compensation should be increased by 1 to 2 stops. If the face color is dark and the background has color, exposure compensation should be
Set to "0". If the face color is brighter and the background is white, the exposure compensation should be set to "-1/3" or "-1/2";
f) Focus. It is advisable to select the point focus mode, the focus point is the eyes of the portrait, and the distance between the lens and the photo to be rephotographed is slightly larger than the nearest
Focal distance;
g) Composition. When re-shooting, it is advisable to make full use of the maximum pixels of the camera, so that the re-photographed photos should be centered and filled with the viewfinder frame as much as possible.
B.3 Scanning techniques
B.3.1 Scanner selection
A roller or flat scanner with a density range (pixel depth) greater than 3.0 should be used.
B.3.2 Display selection
The setting of the monitor is an important factor that affects the visual effect of photo scanning. In order to obtain a real scanning visual effect, the brightness of the display,
Parameters such as color should be consistent with or slightly higher than those set by the scanner.
B.3.3 Scan Settings
The color mode should be color (RGB), and the resolution should not be less than 600dpi.
B.3.4 Scan operation
When scanning photos, the photos should be placed in the best scanning area of the scanner. Pre-scan the photo, according to the scanning effect, there are
Targeted adjustment of scanning parameters.
To obtain the best scanning area, you can do the following.
a) Set all control parameters of the scanner to automatic or default state;
b) Select all areas and scan a blank, white, opaque sample with low resolution;
c) Open the scanned image of the sample in professional image processing software, and use "Image→Adjust→Hue Equalization Command" to perform
Processing, that is, you can see where there are cracks, streaks, and black spots on the scanner. The area without the above defects is the best scanning area.
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