Camera Sensor Technologies – An Overview [2024]

Introduction to Camera Sensor Technology

The development and spread of consumer electronics with imaging capabilities underscore the increasing importance of camera image processing.

Camera Sensor integration, image sensor integration, and camera image processing methods are widely utilized in various applications

From consumer to computer vision to industrial, defense, multimedia, sensor networks, surveillance, automotive, and astronomy.

Machine vision covers flat panel displays, PCBs, semiconductors, warehouse logistics, transportation systems, crop monitoring, and digital pathology.

Advancements in industrial camera sensor and image sensor technology drive demand for compact cameras.

According to Skyquestt, With a projected size of USD 16.25 billion in 2019 and a projected growth rate of 9.6% during the forecast period (2024–2031), the image sensor market is expected to reach USD 39 billion by 2031 from USD 16.36 billion in 2023.

There are four main segments in the global image sensor market: technology, processing type, application, and region. 

It is divided into four categories, such as contact image sensor (CIS), charge-coupled device (CCD) image sensor, front side illuminated (FSI), backside illuminated (BSI), and complementary metal oxide semiconductor (CMOS) image sensor.

What is Camera Image Processing

Customers building next-generation camera sensor products for various applications may rely on Camera Image Processing to provide the best solutions.

The current generation of intelligent devices, which represent a quantum jump in sophistication, is made possible by camera competence.

This includes camera integration, camera image processing, CMOS image sensor technology tuning, and other related capabilities.

The camera gathers data about the visual scene by first focusing and sending light via the optical system. 

An image sensor and an analog-to-digital (A/D) converter are then used to sample the visual data. 

The focal point of the lens is usually controlled by the zoom and focus motors.

Camera image processing involves adjusting and altering camera-captured images using algorithms. 

Camera image processing involves:

• Adjust brightness, contrast, and color balance for improved quality.
• Reducing noise and applying feature extraction filters.
• Compressing images for efficient storage.
• Recognizing objects and tracking movement.
• Stitching images and estimating depth.
• Integrating with augmented and virtual reality.

Working on Camera Sensor Integration

Camera sensor Integration is the period when the camera’s clocks are configured to trap and hold a charge.

The behavior of the readout electronics serves as the integration’s boundary, which is unrelated to the shutter’s exposure.

The incident light (photons) is focused by a lens or other optics and is received by the image sensor in a camera system.

The sensor’s ability to transmit data as either a voltage or a digital signal to the following stage will depend on whether it is CCD or CMOS.

The image sensor in a camera system receives incident light, or photons, that have been focused by means of a lens or other optics. 

The information transferred to the following stage by the sensor will be either a voltage or a digital signal, depending on whether it is a CCD or CMOS sensor. 

CMOS sensors use an on-chip analog-to-digital converter (ADC) to transform photons into electrons, voltage, and finally a digital value.

Typical CMOS Camera Layout

Detailed explanation of the Camera/Image sensor

The choice of the appropriate camera sensor has become extremely important and varies from product to product because cameras have a wide variety of uses in many industries.

Therefore, in addition to having a lot of pixels, factors like drive technology, quantum efficiency, and pixel size structure all impact imaging performance in different ways.

Nowadays, charge-coupled devices(CCD camera sensors) and complementary metal oxide semiconductor technology (CMOS) imagers make up the majority of sensors.

Due to inadequate illumination and other environmental factors, the captured image may contain some unnecessary elements despite each specific sensor, processor, and lens combination.

As a result, the raw image would need a lot of processing to produce a high-quality image.

The image processing sector is currently one of the global businesses with the fastest growth rates, and as a result, it is a crucial area of engineering study.

ISP, which is either externally integrated or embedded within the video processor, does image processing.

An image signal processor (ISP) is a processor that receives a raw image from the image sensor and outputs a processed version of that picture (or some data associated with it).

To deliver a high-quality image for a specific camera sensor and use case, an ISP could carry out several procedures, including black level reduction, noise reduction, AWB, tone mapping, color interpolation, autofocus, etc.

Obtaining the ideal image or video quality is tricky for each use scenario. A lot of filtering and iterations are necessary to attain a desirable outcome.

To evaluate the camera sensors’ tuning, image quality, and image resolution, various types of labs tools are required, such as;

• ISO Resolution Charts & Color Tests under controlled lighting
• Test Charts – Lens Distortion, Lens Shading & AWB
• Light Booth – to create different light conditions for sharpness & contrast.
• Chroma Meter & IR Source and IR Power Meter
• Greyscale & Color Chart

Here’s a clear explanation of the process of capturing and processing images in a digital camera:

Color Detection: A mosaic filter (1) covers the image sensor, enabling it to detect color and light intensity.

Light Sensing: The camera lens focuses the light coming from the subject onto the image sensor (2).

Signal Conversion: An electrical signal that could be weak is produced by the sensor. Analog electronics (3) increase this signal by amplifying it.

Digital Conversion: After being amplified, the signal is passed to an analog-to-digital converter (4), which changes it into digital data that the camera can process more easily.

Image Processing: The digital data is routed to the image processor (5), where it is subjected to several enhancements and modifications, including sharpening and color correction.

Temporary Storage: Processed photos may be stored in the camera’s buffer (6) indefinitely while they wait to be written to the memory card.

The basis for how digital cameras take and create images is thus the camera sensor, which is essential in transforming light into digital information that can be further processed and saved.

Overview of Types of Camera Sensors

For sensitive, quick imaging of a range of samples for several applications, quantitative scientific cameras are essential. Since the invention of the first cameras, camera technology has developed significantly.

Today’s cameras can push the boundaries of scientific imaging and enable us to view previously invisible things.

The camera’s beating heart is the photons, electrons, and grey levels used to create an image on the sensor.

The various camera sensor types and their features are covered here, including

• Charge-coupled device (CCD)
• Electron-multiplying charge-coupled device (EMCCD)
• Complementary metal-oxide-semiconductor (CMOS)

Sensor Fundamentals

The transformation of light photons into electrons is the first process for a sensor (known as photoelectrons). Quantum efficiency (QE), which is displayed as a percentage, is the efficiency of this conversion.

All electrons have a negative charge that underlies the operation of all the sensor types covered here (the electron symbol being e-).

This implies that positive voltages can attract electrons, making it possible to move electrons across a sensor by applying a voltage to particular sensor regions.

The Above Image explains, how an electron charge is moved through a sensor’s pixels.

A pixel (blue squares) is struck by photons (black arrows), which are then transformed into electrons (e-), which are then stored in a pixel well (yellow).

These electrons can be moved pixel by pixel anywhere on a sensor by employing a positive voltage (orange) to transfer them to another pixel.

On a sensor, electrons can be carried in any direction in this way, and they are often moved to a location where they can be amplified and turned into a digital signal, which can then be presented as an image.

Every type of camera sensor, though, experiences this process differently.

CCD

The first digital camera sensors were CCDs, which have been used in scientific imaging since the 1970s.

For years, CCDs were actively used, ideal for high-light applications like cell documentation or imaging fixed samples.

This technology’s lack of sensitivity and speed constrained the number of samples that could be scanned at acceptable levels.

CCD Fundamentals

After being exposed to light and changing from photons to photoelectrons in a CCD, the electrons are transported down the sensor row by row until they reach the readout register, which is not exposed to light.

Photoelectrons are transferred simultaneously into the readout register and the output node.

The images are processed by imaging software on this node, amplified to readable voltage, and transformed into digital grey levels using an ADC.

The above image explains, How a CCD sensor works.

Photons hit a pixel, converting to electrons that move to the sensor’s readout register, then to the output node where they become voltage, then grey levels, and finally displayed on a PC.

The above image explains the Different types of CCD sensors. The full-frame sensor is also displayed. Grey areas are masked and not exposed to light.

The frame-transfer sensor has an active image array (white) and a masked storage array (grey), while the interline-transfer sensor has a portion of each pixel masked (grey).

The camera technology can be quantitative since the a linear relationship between the number of electrons and photons.

A full-frame CCD sensor is a kind shown in Figure 2, although there are also additional designs known as frame-transfer CCD and interline-transfer CCD.

EMCCD

The Cascade 650 from Photometrics introduced EMCCDs to the scientific imaging market for the first time in 2000.

EMCCDs provide quicker and more sensitive imaging than CCDs, making them ideal for photon counting or low-light imaging devices.

This was accomplished in several ways via EMCCDs. The cameras’ back illumination (which raises the QE to over 90%) and massive pixels (16-24 m) significantly raise their sensitivity.

The EM in the EMCCD, or electron multiplication, is the most important addition.

EMCCD Fundamentals

Electrons go from the image array to the masked array, and then onto the readout register in a manner that is remarkably similar to frame-transfer CCDs.

The EM Gain register now becomes the primary point of distinction. Impact ionization is a technique EMCCDs to drive more electrons out of the silicon sensor size, doubling the signal.

Users can select a number between 1 and 1000 to have their signal multiplied that many times in the EM Gain register as part of this step-by-step EM process.

When an EMCCD receives a signal of 5 electrons, and the EM Gain is set to 200, the output node will receive a signal of 1000 electrons.

Due to its ability to be multiplied up above the noise floor as many times as needed, EMCCDs can now detect tiny signals.

The above image explains, How an EMCCD sensor works. Photons hit a pixel and are converted to electrons, which are then shuttled down the sensor integration to the readout register.

They are amplified using the EM Gain register, sent to the output node, converted to a voltage, grey levels, and then displayed with a PC.

EMCCDs are far more sensitive than CCDs thanks to the combination of large pixels, back illumination, and electron multiplication.

EMCCDs are quicker than CCDs as well.

Because the speed at which electrons are moved around a sensor increases read noise, CCDs move electrons much slower than their maximum potential speed.

Every signal has a set +/- a value called read noise.

For example, if a CCD detects a signal of 10 electrons with a read noise of 5 electrons, the signal could be read out at any value between 5 and 15 electrons, depending on the read noise.

As a result, CCDs transport electrons more slowly to lessen read noise, significantly impacting sensitivity and speed.

CMOS

Although MOS and CMOS technology have been around since the 1950s, well before the development of CCD.

It wasn’t until 2009 that CMOS cameras reached a quantitative level sufficient for scientific imaging.

For this reason, CMOS cameras for science are sometimes referred to as scientific CMOS or CMOS.

CMOS sensor technology allows for greater speeds due to its parallel operation, unlike CCD and EMCCD which rely on different methods of sequential operation.

CMOS and sCMOS image sensor market growth

According to datahorizzonresearch, the market growth of CMOS and sCMOS image sensor market size was valued at USD 23.3 Billion in 2023 and is expected to reach a market size of USD 40.8 Billion by 2032 at a CAGR of 6.4%.

The market for complementary metal-oxide semiconductors, or CMOS and sCMOS image sensors, has grown significantly in recent years.

The growth behind these image sensors is due to the growing need for high-performance, low-power, and reasonably priced imaging solutions across a range of industries.

CMOS Fundamentals

Every pixel in a CMOS sensor technology contains miniature electronics, including an amplifier and a capacitor.

This implies that the pixel converts a photon into an electron and that the electron is then instantly changed into a readable voltage while still on the pixel.

Additionally, each ADC has to read out considerably less data than a CCD/EMCCD ADC, which must read out the complete sensor because there is an ADC for every column.

Compared to CCD/EMCCD technology, this combination enables CMOS sensors to operate parallel and analyze data more quickly.

As CMOS sensors have a far lower read noise than CCD/EMCCD, they can work with weak fluorescence or live cells and move electrons much slower than the projected maximum speed.

This enables them to conduct low-light imaging.

CMOS image sensor block diagram

The above image explains, How a CMOS sensor works.

Photons hit a pixel, are converted to electrons, and then to the voltage on the pixel. Each column is read out separately by individual ADCs and then displayed with a PC.

Conclusion

Scientific imaging technologies have continued to improve: from CCD to EMCCD, sCMOS, and back-illuminated sCMOS.

These advancements aim to provide optimum speed, sensitivity, resolution, and field of view for various applications.

By selecting the best camera manufacturer technology for your imaging system, you can enhance all aspects of your studies and conduct quantitative research.

While CCD and EMCCD technologies were popular for scientific imaging, sCMOS technology has emerged in recent years as the best option for imaging in the biological sciences.

Frequently asked questions

Q: What is the future of CMOS image sensors?

High-Resolution Sensors: There is a growing trend towards higher resolution CMOS image sensors, enabling sharper and more detailed images. 

3D Imaging: There are now more uses for CMOS image sensors in augmented reality, industrial inspection, and healthcare thanks to their development of 3D imaging capabilities.

Q: What is the latest technology in cameras?

AI Transforming Photography: Camera technology is being revolutionized by AI and machine learning, with possible uses ranging from improving image authenticity to countering bogus AI-generated photos.

Q: What is the future technology for security cameras?

Future home security cameras might have artificial intelligence derived from deep neural networks to solve this.

These neural networks will be able to detect suspicious behavior and transmit an alarm in real time, instead of depending just on motion detection.

Q: What is sensor integration?

Without the container, an integrated sensor is only the sensor’s fundamental technology. It enables various sensor technologies to be “integrated” or combined into a single plug-and-play component.

Q: What is image sensor technology?

The image sensor, which powers every digital camera, is essential to this.

The sensor collects light and transforms it into an electrical signal that is subsequently processed to create a digital image, much like the retina in a human eye does the same thing by translating light into nerve impulses that the brain can understand.

Q: What is an imaging sensor in remote sensing?

Optical, thermal, or SAR imaging systems are commonly used with imaging sensors.

Optical imaging systems often generate panchromatic, multispectral, and hyperspectral imagery using visible, near-infrared, and shortwave infrared spectrums.

Q: How does a digital camera work step by step?

Light entering a digital camera through the lens hits an image sensor. The camera processes the signal that the image sensor outputs to produce image data, which is then saved on the memory card.

The picture display allows for simultaneous viewing of the image.

Q: How do sensors actually work?

A sensor is an apparatus that senses changes in its surroundings and reacts to an output from another system.

A sensor transforms a physical event into a quantifiable analog voltage, or occasionally a digital signal, which is then sent for reading or additional processing or transformed into a display that is readable by humans.

Q: What are the Types of image sensors used in digital cameras?

There are two major types of image sensors: CCD, or charge-coupled device, and CMOS, or complementary metal oxide semiconductor.

Q: What is a sensor in photography?

The image sensor, which powers every digital camera, is essential to this.

The sensor collects light and transforms it into an electrical signal that is subsequently processed to create a digital image, much like the retina in a human eye does the same thing by translating light into nerve impulses that the brain can understand.

Q: What type of technology does CCD video imaging use?

An integrated circuit that is sensitive to light and uses photons and electrons to create images is called a charge-coupled device, or CCD. Pixels are separated from the image elements using a CCD sensor.

Every pixel is transformed into an electrical charge, the strength of which is correlated with the amount of light it was able to collect.

Q: What are the applications of CMOS image sensors?

The primary purpose of these sensors is to produce images for digital cameras, digital video cameras, and digital CCTV cameras.

Moreover, barcode readers, astronomical telescopes, and scanners all use these electronic chips. Low-cost consumer gadgets are possible thanks to CMOS’s inexpensive manufacture.