INTRODUCTION TO DIGITAL CAMERA
WORKING AND RESOLUTION
A digital camera (or digicam) is a camera that takes video or still photographs by the process of recording images on an electronic image sensor. Most cameras sold today are digital and digital cameras are incorporated into many devices ranging from PDAs and mobile phones (called camera phones) to vehicles.
Digital and film cameras share an optical system, typically using a lens with a variable diaphragm to focus light onto an image pickup device. The diaphragm and shutter admit the correct amount of light to the imager, just as with film but the image pickup device is electronic rather than chemical. These cameras, digital cameras can display images on a screen immediately after being recorded, and store and delete images from memory. These cameras can also record moving video with sound. Some digital cameras can crop and stitch pictures and perform other elementary image editing.
The resolution of a digital camera is often limited by the image sensor that turns light into discrete signals. The sensor is made up of millions of "buckets" that essentially count the number of photons that strike the sensor. The brighter the image at a given point on the sensor, the larger the value that is read for that pixel. Depending on the physical structure of the sensor, a color filter array may be used which requires a demosaicing/interpolation algorithm. The number of resulting pixels in the image determines its "pixel count". For example, a 640x480 image would have 307,200 pixels, or approximately 307 kilopixels; a 3872x2592 image would have 10,036,224 pixels, or approximately 10 megapixels.
WORKING AND RESOLUTION
A digital camera (or digicam) is a camera that takes video or still photographs by the process of recording images on an electronic image sensor. Most cameras sold today are digital and digital cameras are incorporated into many devices ranging from PDAs and mobile phones (called camera phones) to vehicles.
Digital and film cameras share an optical system, typically using a lens with a variable diaphragm to focus light onto an image pickup device. The diaphragm and shutter admit the correct amount of light to the imager, just as with film but the image pickup device is electronic rather than chemical. These cameras, digital cameras can display images on a screen immediately after being recorded, and store and delete images from memory. These cameras can also record moving video with sound. Some digital cameras can crop and stitch pictures and perform other elementary image editing.
The resolution of a digital camera is often limited by the image sensor that turns light into discrete signals. The sensor is made up of millions of "buckets" that essentially count the number of photons that strike the sensor. The brighter the image at a given point on the sensor, the larger the value that is read for that pixel. Depending on the physical structure of the sensor, a color filter array may be used which requires a demosaicing/interpolation algorithm. The number of resulting pixels in the image determines its "pixel count". For example, a 640x480 image would have 307,200 pixels, or approximately 307 kilopixels; a 3872x2592 image would have 10,036,224 pixels, or approximately 10 megapixels.
Since the first digital backs were introduced, there have been three main methods of capturing the image, each based on the hardware configuration of the sensor and color filters.
The first method is often called single-shot, in reference to the number of times the camera's sensor is exposed to the light passing through the camera lens. Single-shot capture systems use either one CCD with a Bayer filter mosaic, or three separate image sensors
The second method is referred to as multi-shot because the sensor is exposed to the image in a sequence of three or more openings of the lens aperture. There are several methods of application of the multi-shot technique. The most common originally was to USE single image sensor with three filters (once again red, green and blue) passed in front of the sensor in sequence to obtain the additive color information. Another multiple shot method is called Microscanning. This technique moved the physical location of the sensor chip on the focus plane of the lens to "stitch" together a higher resolution image than the CCD would allow otherwise. A third version combined the two methods without a Bayer filter on the chip.
Dramatic improvements in single-shot cameras and raw image file processing at the beginning of the 21st century made single shot, CCD-based cameras almost completely dominant, even in high-end commercial photography. Single shot cameras remained somewhat common.
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