Summary of Common Camera Terminology Abbreviations

January 13, 2024

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AA: Automatic calibration process

ABCC (Assisted Bad Cluster Correction): Assisted bad cluster correction

ABF (Adaptive Bayer Filter): Adaptive Bayer filter, Raw domain single frame noise reduction. Bilateral Filter is first used to remove noise and edges, and then soft threshold processing is performed. Before the ISP process, if the intensity will affect the image clarity, the intensity will be smaller.

Accelerate Meter: gravity acceleration sensor

ACF (Auto Correlation Function): Autocorrelation coefficient, describing the spatial characteristics of noise

ADC (Analog-Digital Convert): analog-to-digital conversion

AEC (Automatic Exposure Control): automatic exposure control

AF: autofocus, CDAF (Contrast Detection AF) contrast focus, PDAF (Phase Detection AF) phase focus

AFD (Automatic Flicker Detection): automatic flicker detection

AGW (Advanced Gray World): Grayscale world. The basic idea is that if the scene contains enough colors, then the average value is gray, which is used to calculate white balance.

ANR (Advanced Noise Reduction): Single-frame noise reduction, which uses a variety of filter combinations to smear or reduce the intensity of high-frequency noise. It first downsamples and reduces chroma noise and luma noise at the same time. Edge preserving filter + (1 - α)×Low pass image = Result

Anti-banding = defilicker: remove stripes, achieved by adjusting exposure time

AOI (Angle of Incidence): Angle of incidence

ASF (Adaptive Spatial Filter): Adaptive spatial domain filtering, regarded as edge enhancement, enhances details through high-pass filtering


BCC (Bad Cluster Correction): Bad pixel pair correction

BG (Bayer Grid): Bayer grid

BLC (Black Level Calibration): Black level correction. ①The AD chip cannot convert a very small voltage value and adds deviation; ②sensor dark current

Bokeh: portrait blur

BPC (Bad Pixel Correction): Bad pixel correction, caused by sensor technology (static bad pixels) and noise (dynamic bad pixels)

BPS (Bayer Processing Segment): Hardware module, mainly used for dead pixel removal, phase focusing, demosaicing, downsampling, HDR processing and Bayer's hybrid noise reduction processing of photographed image data.

BPS has more GIC, HNR, multi-frame and other modules than IFE.

BSI (Back Side Illumination): A back-illuminated sensor with a metal wiring layer behind it, which solves crosstalk. The corresponding FSI (Front Side Illumination) is a front-illuminated sensor.

BSP (Board Support Package): board-level support package, development package


CAC (Chromatic Abberation Correction, Color Aliasing Correction, Color Artifact Correction): chromatic aberration correction, depurple, causes: vertical axis chromatic aberration and axial chromatic aberration

CAF (Contrast AF): contrast detection method

CAF (Continuous Auto Focus): continuous auto focus

CC (Color Correction): color correction

CCM (Color Correction Matrix): color correction matrix

CCM (CMOS Camera Module): CMOS camera module

CCT (Correlated Color Temperature): color temperature

CDAF (Contrast Detection AF): contrast focus

CE (Chroma Enhancement): Chroma enhancement

CIS (CMOS Image Sensor): CMOS image sensor

COB (Chip On Board): Chip on board packaging

CPP (Camera Post Processor): camera post-processing

CRA (Chief Ray Angle): Chief ray angle. Excessive CRA will cause color inversion

CSC (Color Space Convert): color space conversion

CSM (Color Space Matrix): color space matrix

CST (Color Space Transform): color space conversion

CV (Color Conversion): color space conversion, such as RGB→YCrCb


Depurple: remove purple edges, correct vertical and horizontal chromatic aberration through calibration + correction

DOF (Depth of Field): depth of field

DPC (Defect Pixel Correction): Dead pixel correction. Classification of dead pixels: static dead pixels (process), dynamic dead pixels (gain, temperature), hot pixels (bright and dead pixels), dead pixels (dark and dead pixels), weak pixels (dead pixels that are not particularly bright or dark)

DR (Dymatic Range): Dynamic range, 20log (maximum unsaturated current/bottom current), reflects the maximum and minimum brightness that the display device can present. The larger the DR, the richer the light and dark details of the image.


EE (Edge Enhancement): edge enhancement

EEPROM: It exists inside the module in the form of an independent IC and can be erased and written repeatedly.

EIS (Electric Image Stabilization): Electronic anti-shake technology, which uses gravity sensors and gyroscopes to detect shake amplitude, dynamically adjust ISO, shutter and imaging algorithms, and realize motion compensation through software

Encoder: compression encoding

EOL (End of Line): product testing, inspection, packaging

EV (Exposure Value): exposure compensation

ESF (Edge Spread Function): edge spread function, differentiate to get LSF (Line Spread Function) line spread function

EXIF (Exchangeable Image File): Changeable image file


FD (Face Detection): Face detection

FR (Face Recognition): Face recognition

FIR (Finite Impulse Response) filter: Finite impulse response filter, used for time domain multi-frame denoising

FOV: field of view

FSI: front-illuminated sensor

FWC (Full Well Capacity): Maximum well capacity, the maximum amount of charge that the photodiode capacitance of each pixel can accumulate


GIC (Green Imbalance Correction): Semiconductors, microlens and other reasons cause Gr and Gb imbalance

GM (Golden Module): Golden module

GTM (Global Tone Mapping): global tone mapping

Gyro: Gyro


HAF (Hybrid Auto Focus): hybrid focus

HDR (High Dymatic Range): High dynamic range. Process: Extract grayscale image → Image registration → Grayscale fusion → Image color restoration. HDR common problems: ghosting, exposure time selection, unnatural color effects

Staggered HDR: Single-frame progressive HDR, each line is processed by three sets of readout circuits for short, medium and long exposures.

3HDR: pixel-level exposure

HNR (Hybrid Noise Reduction): Hybrid noise removal module, which is composed of frequency domain noise reduction, gradient smoothing and spatial domain noise reduction of discrete cosine transform (DCT transform). It is only used to reduce luma noise, not chroma noise.


ICA (Image Correction and Ajustment): Intra-frame distortion correction, in the IPE module

ICL (Imaging Codec Layer): Image coding and decoding layer

IIR (Infinite Impulse Response) filter: infinite impulse response filter, used for time domain multi-frame denoising

IFE (Image Front End): The data output by the Sensor will first arrive at the IFE. This hardware module will do some color correction, downsampling, and demosaicing statistics for preview and video 3A data processing.

IMU (Inertial Measurement Unit): Inertial sensor, a sensor that detects and measures acceleration and rotational motion

IPE (Image Processing Engine): This hardware module is mainly composed of NPS and PPS, and is responsible for image processing tasks such as hardware noise reduction (MFNR, MFSR), image cropping, noise reduction, color processing, and detail enhancement. ICA-Intra-frame distortion correction, ANR-Noise removal

IS (Image Stabilization): image stabilization


2D-Lut: HSL space algorithm, divides H/S to form a two-dimensional lookup table, H-24 intervals (15°), S-16 intervals (0.0625)

LA (Luma Adaptation): brightness adjustment

LCA (Lateral Chromatic Abberation): Lateral Chromatic Aberration

LDC (Lens Distortion Correction): lens distortion correction

LHA: lens mount package

Light Meter: light meter

Logarithmic Sensor: Compresses the image from linear to log domain in HDR, and uses the inverse function to restore to linear on the isp side

LSC (Lens Shading Correction): Lens shading correction, lens shading includes luma shading and color shading

LSF (Line Spread Function): Line spread function, the change process of ESF on a line, and the integration is obtained by ESF (edge spread function)

LTM (Local Tone Mapping): local tone mapping, enhancement based on local brightness


MCE (Memory Color Enhancement): memory color enhancement

MCTF (Motion Compensated Temporal-Filtering): Motion compensation is to predict and compensate the current local image through previous local images. It is a time domain filtering method that reduces redundant information in frame sequences. For example, in HDR's Motion Detection, the moving area blends more short frames, and the static area blends more long frames.

MLC (Misleading Color): Misleading color. For example, blue objects are recognized as high color temperature light sources, and yellow objects are recognized as low color temperature light sources.

MFNR (Multi-frame Noise Reduction): Multi-frame noise reduction

MTF (Modulation Transform Function): Modulation transfer function, a function in which modulation degree changes with spatial frequency

The relationship between MTF and demosaic: sampling frequency ≥ 2 signal frequency

MTF, sharpening, and focus influence each other


NR (Noise Reduction): Noise reduction

NPS (Noise Power Spectrum): Noise power spectrum, FFT of ACF

NPS (Noise Processing Segment): Noise processing module, located in the IPE hardware module


OB (Optical Black): Black level, 10-bit raw image is maintained at 64 through internal processing of the sensor

OIS (Optical Image Stabilization): optical image stabilization

OTP (One-Time Programming): A fuse-type register reserved inside the sensor for users to read and write. It cannot be erased or written repeatedly.


PDAF (Phase Detection AF): phase focus

PDPC (PD Pixel Correction): PD pixel correction

PLD (Physical Layer Driver): physical layer driver

PPS (Post Processing Segment): post-processing module

PSF (Point Spread Function): brightness distribution function after point light source imaging


RDI (Raw Dump Interface): raw data dump port

RI (Relative Intensity): relative brightness

RGB2YUV: Separates brightness and chroma. For example, the brightness details of the image will not be lost when removing color noise, and the color details of the image will not be lost when brightness is processed. YCrCb is a color space. Each pixel has a Y, and 2 to 4 pixels share UV.

Rolloff: Due to the limitation of the amount of light entering the module lens, the lens image will have dark corners. The Rolloff algorithm can improve Y_corner/Y_center


SAT: Use spatial alignment transformation technology to achieve smooth switching between shots

SCD (Scene Change Detect): Scene change detection

SCE (Skin Color Enhancement): Skin color enhancement

SFR (Spatial Frenquency Response): spatial frequency response, used in imaging systems (including optical systems), Fourier transform of LSF

Shading: Image vignetting, influencing factors: focal length, aperture

luma shading: Lens has different refractive index at each position and center. Due to the limitations of the camera lens diameter, aperture size, and gasket aperture, part of the off-axis beam is blocked, reducing the illumination of the peripheral field of view.
Color shading: Lens has different shifts for different spectra, causing light of different wavelengths in the incident light to fall on different positions of the Sensor.
SMT (Surface Mounted Technology): component mounting technology

SNR (Skin Noise Reduce): skin color noise reduction

SNR (Signal-to-noise Ratio): signal-to-noise ratio

SOC (System on Chip): system-level chip, including AP (Application Processor) application processor, BP baseband processor, GPS global positioning system, RAM memory, ROM storage

SOF (Start of Frame): Start of frame

SR (Super Resolution): super resolution

STD (standard deviation): standard deviation

SWG (Simple Gray World): Simple gray world, a classic white balance algorithm based on the global statistical characteristics of the image


Tele: Telephoto

TF (Temporal Filter): Temporal noise reduction, the core is ghost detection (by comparing the difference between the current frame and the previous frame, determine which part of the current frame is the moving area and which part is the static area) and blending, difficulty: frame Balance with frame alignment, moving object detection, local single-frame noise reduction and multi-frame noise reduction intensity

TOF (Time Of Fly): Laser ranging method


USM (Unsharp Masking): Unsharp Mask

U-tele: periscope telephoto


VCM (Voice Coil Motor): voice coil motor


ZSL (Zero Shutter Log): Zero-delay photography