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Understanding Imaging Systems

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Understanding Imaging Systems

A very popular saying that has been prevalent from the ancient times quotes “A picture is worth a thousand words”. This saying actually carries a lot of meaning and context if looked upon carefully. From the start of time, mankind in general has been greatly fascinated by the sheer possibility of being able to capture moments and events for eternity. This idea although started by handmade drawings, paintings and sometimes statues. As it was handmade, some people had the talent to excel in it whereas other who did not were left in with just amazement and jealousy of the masterpieces that were being created.

In the modern world this is not the case though, technology has become so advanced that it has brought each of us with the same level graphical prowess and equipment that everyone is able to make up their own masterpieces.

Camera technology has become so advanced these days that the image and video quality that it is shooting is rivaling our perception of reality. Not only that but the extra dimensions it is continuously adding to our lives through artificial intelligence modes and Virtual or augmented reality, it is really blurring the lines between what is real and what is actually computer generated.

Digital cameras work by storing images on board not as a sequence of light shades incident on the sensor but rather as a pattern of numbers (as computers and machines nowadays are shifting more and more towards binary data interchange). This produces some key benefits to the images as it can be stored at much faster rate as well as edited. They images being captured in the digital mainstream can be shared across various platforms and avenues without much of an effort.

In a digital camera, exactly the opposite happens to the situation in our eyes. Light from the subject moves towards the camera lens.  The light in essence is the image that needs to be captured, so when it is incident on the camera sensor, a variation and combination of pixels are lit up. The imaging chip measures the different amplitudes and colors of that pattern and converted into numbers. This stream of numbers is our image in the digital form, these are then transmitted to the computer or processor of the imaging system that translates this numeric code into full blown picture.

At the heart of imaging systems are the image sensors. As described above the most important and trivial part in the whole process of image capturing is actually the light from subject striking the imaging sensors. The imaging sensor needs to be as good as possible to capture an image that is both visually appealing and carries the right amount of detail. The modern sensors are wide array of photodetectors called pixels. The sensor broadly falls into two categories which is the Charged-Couple Device (CCD) and Complementary Metal Oxide Semiconductor (CMOS).

The CCD (Charged-Couple Device) sensors are based on a silicon chip with photosensitive sites to capture the variations of light for a particular image. The name itself describes the way the data packets are transferred from the chip to the actual location where they are interpreted by the computer algorithms. A certain sequence of clock pulses creates a potential well to transfer charge packets and after they are converted to voltages by the capacitor. The point of interest in this sensor is the fact that this sensor is an analog sensor so it needs an additional analog to digital converter as well as the aid of synchronization pulses which make sure that the sequence of the number stream is read out in the desired order for the correct translation in to the image. This also introduces a major drawback in speed of the CCD sensors. One other major setback that may arise in these types of sensors is the fact of blooming as charge packets from photoreceptor site spills or leaks into the other causing bright spot or more commonly known as light bleeding. A reduce in speed and light bleeding is compensated by the increase in pixel to pixel sensitivity resulting in higher sensitivity of the eventual image captured.

The other type of sensor incorporated into the camera systems is the CMOS sensor. the basic difference between the working of the two sensors is that the CMOS sensors convert the charge from the photosensitive pixel to voltage at the very site of reception and then using a multiplexer fed into a digital to analog converters.  The CMOS sensors are essentially a digital device with transistors performing the duties of active switching ON and OFF the pixel and even its amplification and charge conversion. This in turn creates a boost in the speed of the performance of the camera sensor but likewise creating low sensitivity as well as high fixed pattern noise due to the fabrication inconsistencies in the multiple charge to voltage conversion circuits located on board. The CMOS sensor is also highly preferred due to its comparatively low power consumption and dissipation as there is less flow of charge and subsequently current. It can also deal with high levels of light intensities preventing blooming or light bleeds in an image.

Apart from the quality of the sensor as well as the different constructions that go into making the sensor, the size of the sensor is also one key parameter that affects the quality of the image. It determines the active area available as it encompasses the system’s field of view (FOV). The bigger the sensor size, the lighter from a potential image can be incident on it, getting in more detail and removing more and more noise for low lighting imagery.

Other terms that are more commonly used in the camera systems is that of frame rate and shutter speed. Frame rates is the number of frames composed in full single second. in a typical system a camera with higher FPS is selected so that it can capture more and more images of the subject in a particular field of view. The shutter speed of a camera determines the number of seconds the sensor is exposed to the light from the potential image. Increasing the shutter speed of the camera helps in having better snapshots of a moving subject.


About Author

Penelope Johnson lives in Oregon USA. She writes about Technology and recent development in the IT sector since 2015. AMITechLabs has highly skilled development team for Mobile applications development company US and Website Development Company. AMITechLabs is an innovative mobile development company based in Portland, Oregon, USA. They have highly skilled staff in developing Apps for mobile phones which also develop complete solutions using hardware and software technologies. They provide services in iPad application development, mobile app development and android app development.

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