GB/T 20733-2022 Digital camera—Vocabulary
1. Scope
This document defines terms and definitions related to technical requirements, test methods and use of digital cameras. This document is applicable to standard setting, documentation, teaching material writing, book editing and document translation related to digital cameras.
2. Normative reference documents
The contents of the following documents constitute an essential clause of this document through normative references in the text. Among them, only the version corresponding to the date of the reference document is applicable to this document; The undated reference document whose latest version (including all amendments) applies to this document.
Measurement of Resolution of GB/T 19953-2005 Digital Camera
Determination of Exposure Index, ISO Sensitivity Value, Standard Output Sensitivity and Recommended Exposure Index of GB/T 20224 Digital Camera
ISO 12234-2 Electronic still image imaging Removable memory-Part 2: Electronic still-picture imaging-Removable memory-Part 2: TIFF/EP image data format
ISO15739 Photography-Electronic still image imaging-Noise measurements
ISO 21550 Photography-Electronic scanners for photographic images
ISO/IEC 10918-1 Information technology Digital compression and coding of continuous-tone still images: requirements and guide-lines
GB/T 20733-2022
IEC 61146-1 Camera (PAL/SECAN/NTSC) Measurement Methods-Part 1: Video cameras (PAL/SECAN/NTSC)-Methods of measurement-Part 1: Non-broadcast single-sensor cameras
IEC 61966-2-1 Multimedia systems and equipment-Color measurement and management-Part 2-1: Color management-Default RGB color space-sRGB (Multimedia systems and equipment-Colour measurement and management-Part 2-1: Colour management-Default RGB color space-sRGB)
EBU Tech3249 Measurement and analysis of the performance of film and television camera lenses
3. Terms and Definitions
3.1 Digital Cameras and Devices
3.1. 1
opto-electronic digital image capture system
A system that converts the spatial distribution of exposure or scene brightness (scene) on the focal plane into digital information. [Source: ISO 14524: 2009, 3.12]
3.1. 2
electronic still camera
electronic still-picture camera
A camera having an image sensor capable of outputting an analog or digital signal describing a photograph and recording this signal on a storage medium (such as a memory card or a magnetic disk, etc.).
[Source: ISO 12233: 2017, 3.6]
3.1. 3
digital still camera; DSC
A device includes an image sensor and generates a digital signal representing a still image.
GB/T 20733-2022
Note: Digital cameras are usually portable handheld devices. Digital signals are usually recorded on removable memory, such as solid-state memory cards or magnetic disks. [Source: GB/T 20224-2006, 3.1, with modifications]
3.1. 4
image sensor
image transducer
An electronic device that can sense optical image information and convert it into an output signal.
Examples: Charge Coupling (CCD), Complementary Metal Oxide Semiconductor (CMOS), etc.
[Source: GB/T 13964-2008, 10.3]
3.1. 5
charge coupled device; CCD
A silicon integrated circuit that converts optical signals into electronic signals.
3.1. 6
Complementary metal-oxide-semiconductor device; CMOS
Semiconductor array with complementary effect of silicon and germanium to convert optical signals into electronic signals.
3.1. 7
analog to digital converter; A/D; ADC
A circuit for converting an analog-digital signal with continuously varying amplitude into a binary digital quantized output signal.
3.1. 8
addressable photo elements
The number of effective photoelectric elements contained in the image sensor is equal to the number of effective lines of photoelectric elements multiplied by the number of effective photoelectric elements
GB/T 20733-2022
er line. Note 1: In order to avoid confusion, the term resolution will not be used when referring to the number of effective photoelectric elements contained in the image sensor.
Note 2: The number of addressable optoelectronic elements may be different for different color recording methods of images. When the signal of the photoelectric element is digitized, the digital value can be used as a reference for the photoelectric element or pixel value.
[Source: ISO 12233: 2017, 3.1]
3.1. 9
pixel pixel
A physical unit on an image sensor that can receive light independently.
[Source: GB/T 29298-2012, 3.4]
3.1. 10
total pixels
The total number of pixels on the image sensor.
3.2 Photographic Optics
3.2. 1
photography
The process of acquiring, processing, or optically reproducing images using chemical or electronic techniques.
3.2. 2
focal length
The distance between the main point of the image side of an optical system and the main focus.
[Source: GB/T 13964-2008, 2.13]
3.2. 3
equivalent focal length
GB/T 20733-2022
When the diagonal length of the image area of the digital camera is equivalent to the diagonal length of the 35 mm camera frame (43.27 mm), the nominal focal length of the lens corresponds to the focal length of the 35 mm camera. Namely:
Equivalent focal length = (43.27 mm/diagonal length of image area) × nominal focal length of lens.
Note: The equivalent focal length is expressed in millimeter (mm).
[Source: GB/T 13964-2008, 2.36]
3.2. 4
digital zoom
Digital camera can enlarge the image in the middle part of the field of view by logical operation interpolation and other methods.
3.2. 5
geometric distortion; GD
In the stored image of a digital camera, the displacement from the theoretical shape of an object (in a plane parallel to the image plane).
Note: The geometric distortion basically comes from the camera lens, and the result is that the straight line is reduced to a curve. There are other factors that can cause geometric distortion, such as the rotational asymmetry of the camera lens or the change of position during the imaging process of the camera.
3.2. 6
TV distortion TV distortion
Linear distortion measured by conventional methods in the field of television as defined in IEC 61146-1 (24 geometric distortion) or EBU Tech 3249 (2.11 photo height distortion).
3.2. 7
Stray flare
In an imaging system, light that falls on an image instead of coming from a corresponding point.
GB/T 20733-2022
Note: flare sometimes refers to Veling glare.
3.2. 8
image flare
Light from the target point and scattered by the optical system beyond the appropriate image point in the image plane area.
Note: The image-spot difference generated by any target point is determined by the image point spread function. Point spread functions are variable for different image points, and often decrease rapidly with the increase of the distance to the image points, and they are usually not radially symmetric for image points at a certain distance from the optical axis.
3.2. 9
Soft stray light veiling flare
Relatively uniform but unnecessary irradiation on the image plane of an optical system caused by a portion of scattered and reflected light from within or outside the field of view of the system entering the system through the entrance pupil.
Note: Light leakage from the optical system shell may cause extra unwanted radiation in the image plane. This kind of radiation may be similar to soft glare.
[Source: ISO 3664: 2009, March 19]
3.2. 10
Soft glare veiling glare
Reflected light from the imaging medium, which will not form an image without modulation.
Note 1: Soft glare brightens the dark part of the image and reduces the contrast.
Note 2: In CIE 122, the soft glare of CRT display is called ambient glare.
3.3 Exposure and Photoelectric Conversion
GB/T 20733-2022
3.3. 1
opto-electronic conversion function; OECF
The relationship between the logarithm of the input value and the corresponding digital output value of the photoelectric digital image acquisition system.
Note: If the interval between the input logarithmic exposure points is very small and the output noise relative to the interval value is small, the OECF may exhibit stepped characteristics. This phenomenon is an illusion of quantitative processing, which should be eliminated by smoothing algorithm or curve fitting of data.
[Source: ISO 14524: 2009, 3.11]
3.3. 1.1
camera opto-electronic conversion function
Camera OECF
The relationship between logarithmic luminance of input scene and digital output value of photoelectric digital image acquisition system.
Note: The unit of measure for this function is lg cd/m ®.
[Source: ISO 14524: 2009, 3.1]
3.3. 1.2
focal plane opto-electronic conversion function; focal plane OECF
Relationship between digital exposure value and digital output value of input focal plane of photoelectric digital image acquisition system.
Note: The unit of measurement for this function is lg lx · s
[Source: ISO 14524: 2009, 3.5]
3.3. 2
digital output level digital output level
digital code value
A digital value assigned to a specific output level.
GB/T 20733-2022
[Source: ISO 14524: 2009, 3.2]
3.3. 3
incremental output signal
The product of the input signal (non-logarithmic brightness or exposure) and the corresponding system gain.
Note: See incremental gain function.
[Source: ISO 14524: 2009, 3.8]
3.3. 4
incremental gain function
A function expressed as the quotient of the change in output level (digital value) divided by the change in input level (brightness or exposure). Note 1: Logarithmic input values are not used for gain determination.
Note 2: If the input exposure point interval is very small and the output noise relative to the quantization interval value is very small, the gain function may exhibit a step-like characteristic. This phenomenon is an illusion of quantization processing, which is eliminated by quasi-leveling operation or data fitting curve. Sometimes it is necessary to fit the input-output data curve, and then determine the gain function by finding the first derivative of the fitting curve equation.
[Source: ISO 14524: 2009, 3.7]
3.3. 5
noise noise
Undue changes in the response of the imaging system.
[Source: GB/T 34074-2017, 3.9]
3.3. 5.1
total noise
All undesirable changes in the digital output obtained by single exposure shooting, including mode noise and random noise. [Source: GB/T 34074-2017, 3.9. 1]
GB/T 20733-2022
3.3. 5.2
fixed pattern noise
Undesired changes in digital output that remain unchanged during exposure.
[Source: GB/T34074-2017, 3.9. 2]
3.3. 5.3
Random noise temporary varying noise
Undesired changes in the digital output from one exposure to the next due to sensor dark current, shot noise, analog processing, and quantization.
[Source: GB/T 34074-2017, 3.9. 2]
3.3. 6
output noise
For a constant input level, the root mean square fluctuation of the median of the digital output level.
[Source: ISO 14524: 2009, March 13]
3.3. 7
Noise spectrum energy distribution
Curve or equation representation of spatial frequency function of two-dimensional image of camera output noise.
3.3. 8
incremental signal to noise ratio
Increments the ratio of the output signal to the electrical mean root of noise (rms) at a specific signal level.
Note: The incremental signal-to-noise ratio is typically expressed as a curve or table showing the relationship between the electrical mean root of noise and the output signal over the entire output signal level range.
3.3. 9
maximum exposure limit
GB/T 20733-2022
A minimum exposure of a digital output level corresponding to the maximum measurable exposure is generated.
Note 1: Maximum measurable exposure is also called saturation or quantization upper limit.
Note 2: See Minimum Exposure Limit.
[Source: ISO 14524: 2009, March 9]
3.3. 10
minimum exposure limit
An incremental output signal equal to the magnitude of the output noise is generated and below the saturated maximum exposure.
Note: See Incremental Output Signal, Maximum Exposure Limit, Output Noise.
[Source: ISO 14524: 2009, 3.10]
3.4 Image Evaluation
3.4. 1
resolution resolution
Measure the ability of the camera system or camera system components to represent picture details.
Note: The indicators of resolution measurement include visual resolution, limit resolution, spatial frequency response (SFR), modulation transfer function (MTF) and optical transfer function (OTF), etc.
[Source: ISO 12233: 2017, 3.22]
3.4. 2
visual resolution visual resolution
The spatial frequency of the black and white lines in the test map reproduced on the display or photo that can be distinguished by the human eye; Due to the influence of false signals, the spatial frequency that can be reproduced is lower than the spatial frequency of the corresponding area in the test diagram.
[Source: ISO 12233: 2017, March 29]
GB/T 20733-2022
3.4. 3
limiting resolution
The number of linewidths per image height measured for a specific resolution test pattern, corresponding to an average degree of modulation equal to the specified reference frequency and its degree of modulation percentage.
3.4. 4
spatial frequency response; SFR
Amplitude response measured by an imaging system as a function of the corresponding input spatial frequency.
Note 1: SFR is generally expressed by the output response curve of input sine wave brightness distribution per unit amplitude in spatial frequency range. Note 2: SFR is reduced to 1 when the spatial frequency is zero.
Note 3: In the equation, the symbol RSFR is used instead of the abbreviation SFR for clarity.
[Source: ISO 12233: 2017, 3.24]
3.4. 5
gray scale
The camera's ability to distinguish neutral spectra (gray light) with different reflectivity (or transmittance).
[Source: GB/T 29298-2012, 3.11]
3.4. 6
cycles per millimetre
cy/mm
A unit of spatial frequency, defined as the number of spatial periods per millimeter.
[Source: ISO 12233: 2017, 3.3]
3.4. 7
GB/T 20733-2022
Line width per image height line widths per picture height
LW/PH
A unit of measure used to specify the width of a feature on a test chart, relative to the height of the effective area of the test chart, which is equal to the effective area of the test chart
GB/T 20733-2022
Appendix A
(File)
Domestic and foreign brand number approximate comparison
The comparison with GB / T 20887.2-2010 and foreign standard are shown in Table A.1.
Table A. 1 Table of domestic and foreign approximate license numbers
The document GB/T 20887.2—2010 EN 10338:2015 VDA239-100:2016 JFS A1001:2014 SAE J2745—2007
1 范围
本文件界定了与数码照相机的技术要求、试验方法以及与数码照相机的使用相关的术语和定义。 本文件适用于与数码照相机相关的标准制定、文件编制、教材撰写、书刊编辑和文献翻译等。
2 规范性引用文件
下列文件中的内容通过文中的规范性引用而构成本文件必不可少的条款。其中，注日期的引用文 件，仅该日期对应的版本适用于本文件；不注日期的引用文件，其最新版本(包括所有的修改单)适用于 本文件。
GB/T 19953—2005 数码照相机 分辨率的测量
GB/T 20224 数码照相机曝光指数、ISO感光度值、标准输出灵敏度和推荐曝光指数的确定
ISO12234-2 电子静止图像成像 可移动存储器 第2部分：TIFF/EP图象数据格式 (Electronic still-picture imaging—Removable memory—Part 2:TIFF/EP image data format)
ISO15739 摄 影 电子静止图像成像 噪声测量(Photography— Electronic still-picture imaging—Noise measurements)
ISO 21550 摄影 摄影图像电子扫描仪 动态范围测量(Photography—Electronic scanners for photographic images)
ISO/IEC 10918- 1 信息技术 连续色调静止图像的数字压缩和编码：要求和指南(Information technology—Digital compression and coding of continuous-tone still images:Requirements and guide- lines)
IEC 61146- 1 摄像机(PAL/SECAN/NTSC)测量方法 第1部分：非广播单传感器摄像机 (Video cameras(PAL/SECAM/NTSC)—Methods of measurement—Part 1:Non-broadcast single- sensor cameras)
IEC 61966-2- 1 多媒体系统和设备 色彩测量和管理 第2-1部分：色彩管理默认RGB色空间 sRGB( Multimedia systems and equipment—Colour measurement and management—Part 2- 1:Colour management—Default RGB colour space—sRGB)
EBU Tech3249 电影和电视摄像机镜头性能的测量和分析(Measurement and analysis of the performance of film and television camera lenses)
3 术语和定义
3.1 数码照相机及器件
3.1.1
光电数字图像拍摄系统 opto-electronic digital image capture system
能将焦平面上的曝光量或景物亮度(场景)的空间分布转换为数字信息的系统。 [来源： ISO14524:2009,3 . 12]
GB/T 20733—2022
3.1.2
电子照相机 electronic still camera
电子静态成像照相机 electronic still-picture camera
具有能输出描述照片的模拟或数字信号的图像传感器，并将此信号记录在存储媒体(如存储卡或磁 盘等)上的照相机。
[来源： ISO12233:2017,3.6]
3.1.3
数字(码)照相机 digital still camera;DSC
包含一个图像传感器并产生表示静态图像的数字信号的装置。
注：数字(码)照相机通常是便携式的手持设备。数字信号通常记录在可移动存储器上，如固态存储卡或磁盘。 [来源：GB/T 20224—2006,3.1,有修改]
3.1.4
图像传感器 image sensor
影像传感器 image transducer
能感受光学图像信息并将其转换成可输出信号的电子器件。
示例：电荷耦合(CCD)、互补性金属氧化物半导体(CMOS)等。
[来源： GB/T 13964—2008,10 .3]
3.1.5
电荷耦合器 charge coupled device;CCD
将光信号转换成电子信号的硅集成电路。
3.1.6
互补性金属氧化物半导体器件 comple-mentary metal-oxicle-semiconductor;CMOS
将光信号转换成电子信号的硅、锗互补效应的半导体阵列。
3.1.7
模拟-数字转换器 analog to digital converter;A/D;ADC
将振幅连续不断变化的模拟数字信号转换成二进制数字式量化输出信号的电路。
3.1.8
可寻址光电元件数 addressable photo elements
图像传感器所包含的有效光电元件数，等于光电元件的有效行数乘以每行的有效光电元件数。 注1:为了避免混淆，当涉及图像传感器所包含的有效光电元件数时，将不采用分辨率这一术语。
注2:对于图像不同的颜色记录方式，可寻址的光电元件数量可能不同。当光电元件的信号被数字化后，数码值可 以作为光电元件或像素值的参考。
[来源： ISO 12233:2017,3 . 1]
3.1.9
像素 pixel
影像传感器上能单独感光的物理单元。
[来源： GB/T 29298—2012,3 .4]
3.1.10
总像素数 total pixels
影像传感器上的像素总量。
3.1.11
有效像素数 effective pixels
影像传感器上能从镜头接受到的光信号，并能被数码照相机最终输出的静态图像数据所反映的像
GB/T 20733—2022
素数。
[来源： GB/T 29298—2012,3.5]
3.1.12
环像素 ring pixel
数码相机图像传感器的光敏像素，在成像区域以外并用于图像处理。
注：图像处理的例子是彩色插值、降噪和空间滤波等。
3.1.13
输出像素数 output pixels
数码照相机以数字文件输出图像的像素数。
3.1.14
像素宽高比 pixel aspect ratio
在两个垂直的采样方向上，采样像素点之间的距离比。
注：如果距离是相等的，像素宽高比为1:1,也就是说的正方形。
3.1.15
图像宽高比 image aspect ratio
图像横纵比率
图像宽度和高度之比。
[来源： ISO12233:2017,3.9;ISO15740:2013,3. 16]
3.1.16
成像尺寸(对面阵列传感器而言) image size(for an area array sensor)
图像传感器的感光区域，即宽度和高度的实际尺寸。
3.1.17
图像输出装置 image output device
实现数字(码)图像硬拷贝或者软拷贝的装置。
[来源： ISO15740:2013,3 . 18]
3.1.18
图像采集装置 image capture device
用于将一个场景或一个固定图像，如打印机、胶片或透明正片，转换成数字图像数据的设备。 [来源： ISO15740:2013,3 . 17]
3.1.19
存储媒体 memory media
能够存储数码照相机图像数据的部件。
注：按结构可以分为内置式和移动式两类，按介质分有固态(如存储卡)和磁记录(如微型硬盘)两种。
3.1.20
可移动存储器 removable memory
可移动形式存储，用于数码照相机中图像数据的数字存储。
注：存储介质可以读/写， 一次编写等，但从相机中取出时是非易失性的，以便保留数据。
3.1.21
存储卡 memory card
特定类型的存储器模块，其物理外形尺寸不大于信用卡(大约为85 mm×55 mm)的大小。
3.1.22
存储模块 memory module
可写入存储器的物理实现，包含与指定物理形状因子、互连定义和访问协议相联系的图像数据
