1 / 16

CCD CMOS Image Sensors

Contents. What is an Image sensorPossible uses for Image SensorsCCD Image SensorsCMOS Image SensorsMain Advantages/Disadvantages between CMOS and CCDQuestions and comments. What is an Image Sensor?. An Image Sensor is a photosensitive device that converts light signals into digital signals (co

ziven
Download Presentation

CCD CMOS Image Sensors

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


    1. CCD & CMOS Image Sensors Marcus Bowden Bruno Garcia COSC 3P92 - Seminar

    2. Contents What is an Image sensor Possible uses for Image Sensors CCD Image Sensors CMOS Image Sensors Main Advantages/Disadvantages between CMOS and CCD Questions and comments 1. 2 mins - marcus 2. 2 mins - marcus 3. 3 mins - bruno 4. 3 mins - bruno 5. 2 mins - bruno 6. 3 mins - marcus/bruno1. 2 mins - marcus 2. 2 mins - marcus 3. 3 mins - bruno 4. 3 mins - bruno 5. 2 mins - bruno 6. 3 mins - marcus/bruno

    3. What is an Image Sensor? An Image Sensor is a photosensitive device that converts light signals into digital signals (colours/RGB data). Typically, the two main types in common use are CCD and CMOS sensors and are mainly used in digital cameras and other imaging devices. CCD stands for Charged-Coupled Device and CMOS stands for Complementary Metal–Oxide–Semiconductor An Image Sensor is a photosensitive device that converts analog signals (namely Light) into digital signals (colours). Typically, the two main types in common use are CCD and CMOS sensors and are mainly used in digital cameras and other imaging devices. CCD stands for Charged-Coupled Device and CMOS stands for Complementary Metal–Oxide–SemiconductorAn Image Sensor is a photosensitive device that converts analog signals (namely Light) into digital signals (colours). Typically, the two main types in common use are CCD and CMOS sensors and are mainly used in digital cameras and other imaging devices. CCD stands for Charged-Coupled Device and CMOS stands for Complementary Metal–Oxide–Semiconductor

    4. Here is a example of a image sensor in a nikon D80 DSLR camera… On the left we have a shot of the Nikon D80 with its mirror down not allowing the sensor to be exposed. On the right, we have the same image but with the mirror in the up position with the 10.2 megapixel sensor exposed.Here is a example of a image sensor in a nikon D80 DSLR camera… On the left we have a shot of the Nikon D80 with its mirror down not allowing the sensor to be exposed. On the right, we have the same image but with the mirror in the up position with the 10.2 megapixel sensor exposed.

    5. Uses? Image sensors are not only limited to digital cameras. Image sensors are used in other fields such as: Astronomy, most notably in the Hubble Space Telescope Machine vision/sensing UV Spectroscopy Etc. Image sensors are not only limited to digital cameras. Image sensors are used in other fields such as astronomy, particularly in the Hubble Telescope, machine vision and sensing as well as UV Spec-tro-scapy just to name a few. Side note: Spectroscopy was originally the study of the interaction between radiation and matter as a function of wavelength (?). Image sensors are not only limited to digital cameras. Image sensors are used in other fields such as astronomy, particularly in the Hubble Telescope, machine vision and sensing as well as UV Spec-tro-scapy just to name a few. Side note: Spectroscopy was originally the study of the interaction between radiation and matter as a function of wavelength (?).

    6. How Image Sensors Work Both CCD and CMOS sensors work by employing photosensitive circuitry that reacts to light and stores the analog signals as digital data, namely an image. They both use different methods to achieve this. First we will take a look at CCD image sensors. Both CCD and CMOS sensors work by employing photosensitive circuitry that reacts to light and stores the analog signals as digital data, namely an image. They use different methods to achieve this. First we will take a look at CCD image sensors. On the left we’re looking at a 10.2 mega pixel CCD sensor as found in the Nikon D60, D80, and D200, with a crop factor of 1.5x Both CCD and CMOS sensors work by employing photosensitive circuitry that reacts to light and stores the analog signals as digital data, namely an image. They use different methods to achieve this. First we will take a look at CCD image sensors. On the left we’re looking at a 10.2 mega pixel CCD sensor as found in the Nikon D60, D80, and D200, with a crop factor of 1.5x

    7. CCD A CCD, or a Charged-Coupled Device, is a photosensitive analog device that records light as a small electrical charge in each of its pixels or cells. In essence a CCD is an collection of CCD cells. The signal captured by the CCD requires additional circuitry to convert the analog light data into a readable digital signal. This is mainly layers of capacitors called Stages which act as a way to transport the analog signal to an array of flip-flops which store the data all controlled by a clock signal. This is the definition of an Analog Shift Register. CCD, or Charged-Coupled Device, is a photosensitive analog device that records light as a analog signal. The signal captured by the CCD requires additional circuitry to convert the analog light data into a readable digital signal. This is mainly layers of capacitors called Stages which act as a way to transport the analog signal to a group of flip-flops which store the data. This is the definition of a analog Shift Register //shift register is a group of flip flops set up in a linear fashion which have their inputs and outputs connected together in such a way that the data is shifted down the line when the circuit is activated. CCD, or Charged-Coupled Device, is a photosensitive analog device that records light as a analog signal. The signal captured by the CCD requires additional circuitry to convert the analog light data into a readable digital signal. This is mainly layers of capacitors called Stages which act as a way to transport the analog signal to a group of flip-flops which store the data. This is the definition of a analog Shift Register //shift register is a group of flip flops set up in a linear fashion which have their inputs and outputs connected together in such a way that the data is shifted down the line when the circuit is activated.

    8. CCD When light strikes a CCD, it acquires an electrical charge according to how much light has hit the particular CCD cell. Each CCD cell can transfer its charge to its neighboring cell and then off to external circuitry. The charge is then read off by an analog-to-digital converter as an integer on a range of 0 to 4095 for most modern DSLR cameras. Lower ranges exist, such as 0-255, for lower quality cameras. When light strikes a CCD, it acquires an electrical charge according to how much light has hit the particular pixel. Each CCD cell can transfer its charge to its neighboring cell. The charge is then read off by an analog-to-digital converter as an integer on a range of 0 to 4095 for most modern DSLR cameras. Lower ranges exist, such as 0-255, for lower quality cameras. When light strikes a CCD, it acquires an electrical charge according to how much light has hit the particular pixel. Each CCD cell can transfer its charge to its neighboring cell. The charge is then read off by an analog-to-digital converter as an integer on a range of 0 to 4095 for most modern DSLR cameras. Lower ranges exist, such as 0-255, for lower quality cameras.

    9. How CCDs Record Colour Each CCD cell in the CCD array produces a single value independent of colour. To make colour images, CCD cells are organized in groups of four cells (making one pixel) and a Bayer Filter is placed on top of the group to allow only red light to hit one of the four cells, blue light to hit another and green light to hit the remaining two. The reasoning behind the two green cells is because the human eye is more sensitive to green light and it is more convenient to use a 4 pixel filter than a 3 pixel filter (harder to implement) and can be compensated after a image capture with something called white balance. Ex. A Bayer filter applied to the underlying CCD pixel Each CCD cell in the CCD array produces a single value independent of colour. To make colour images, CCD cells are organized in groups of four cells and a Bayer Filter is placed on top of the group to allow only red light to hit one of the four cells, blue light to hit another and green light to hit the remaining two. The reasoning behind the two green pixels is because the human eye is more sensitive to green light and it is more convenient to use a 4 pixel filter than a 3 pixel filter An example of the Bayer filter can be seen on the left, Each CCD cell in the CCD array produces a single value independent of colour. To make colour images, CCD cells are organized in groups of four cells and a Bayer Filter is placed on top of the group to allow only red light to hit one of the four cells, blue light to hit another and green light to hit the remaining two. The reasoning behind the two green pixels is because the human eye is more sensitive to green light and it is more convenient to use a 4 pixel filter than a 3 pixel filter An example of the Bayer filter can be seen on the left,

    10. This diagram shows how the recorded light is converted into a voltage and then stored in a cameras memory. On the left the image is recorded with use of the CCD and Bayer filter combination and then when the exposure is complete each rows voltage is transferred to the external cameras circuit board where the analog to digital conversion and other post processing methods take place on the right.This diagram shows how the recorded light is converted into a voltage and then stored in a cameras memory. On the left the image is recorded with use of the CCD and Bayer filter combination and then when the exposure is complete each rows voltage is transferred to the external cameras circuit board where the analog to digital conversion and other post processing methods take place on the right.

    11. A CMOS Sensor

    12. CMOS A CMOS, or Complementary Metal Oxide Semiconductor, each pixel has neighboring transistors which locally perform the analog to digital conversion. This difference in readout has many implications in the overall organization and capability of the camera. Each one of these pixel sensors are called an Active Pixel Sensor (APS).

    14. CMOS The imaging logic is integrated on a CMOS chip, where a CCD is a modular imager that can be replaced. Because of this, design of a new CMOS chip is more expensive. However, APSs are transistor-based, which means that CMOS chips can be cheaply manufactured on any standard silicon production line.

    15. Pros and Cons CCD Needs extra circuitry to convert to digital signal High dynamic range of lighting Less noise due to less on-chip circuitry CMOS Higher cost to develop On-chip analog-to-digital conversion Lower complexity on the sensor leading to faster image capture Reduced power consumption CCD Needs extra circuitry to convert to digital signal High dynamic range of lighting Reduced power consumption CMOS Higher cost to develop On-chip analog-to-digital conversion Lower complexity on the sensor leading to faster image capture CCD Needs extra circuitry to convert to digital signal High dynamic range of lighting Reduced power consumption CMOS Higher cost to develop On-chip analog-to-digital conversion Lower complexity on the sensor leading to faster image capture

    16. Noise and Dynamic Range

    17. Works Cited http://www.dalsa.com/corp/markets/CCD_vs_CMOS.aspx http://electronics.howstuffworks.com/question362.htm http://www.axis.com/products/video/camera/ccd_cmos.htm http://en.wikipedia.org/wiki/Image_sensor http://www.kenrockwell.com http://en.wikipedia.org/wiki/Spectroscopy http://www.nasa.gov/worldbook/hubble_telescope_worldbook.html http://www.sensorcleaning.com/whatisasensor.php Tanenbaum, Andrew S., Structured Computer Organization. Amsterdam: Pearson Education, 2008. Questions/Comments?Questions/Comments?

More Related