Digital Camera

Digital still and digital movie cameras share an optical system, also known as aperture, to focus light onto an image pickup device^[1] The diaphragm and shutter admit a controlled amount of light to the image, just like with film, but the image pickup device is electronic rather than chemical. However, unlike film cameras, digital cameras can display images on a screen immediately after being recorded, and store and delete images from memory. Many digital cameras can also record moving videos with sound. Some digital cameras can crop and stitch pictures and perform basic image editing. ^[2]

History

The first commercial camera phone was the Kyocera Visual Phone VP-210, released in Japan in May 1999. It was called a "mobile videophone" at the time, and had a 110,000-pixel front-facing camera. It stored up to 20 JPEG digital images, which could be sent over e-mail, or the phone could send up to two images per second over Japan's Personal Handy-phone System (PHS) cellular network. The Samsung SCH-V200, released in South Korea in June 2000, was also one of the first phones with a built-in camera. It had a TFT liquid-crystal display (LCD) and stored up to 20 digital photos at 350,000-pixel resolution. However, it could not send the resulting image over the telephone function, but required a computer connection to access photos. The first mass-market camera phone was the J-SH04, a Sharp J-Phone model sold in Japan in November 2000. It could instantly transmit pictures via cell phone telecommunication. By the mid-2000s, higher-end cell phones had an integrated digital camera and by the early 2010s, almost all smartphones had an integrated digital camera.

Image sensors

Image sharpness

An image sharpness is presented through the crisp detail, defined lines, and it's depicted contrast. Sharpness is a factor of multiple systems throughout the DSLR camera by its ISO, resolution, lens and the lens settings, the environment of the image and its post processing. Images have a possibility of being too sharp but it can never be too in focus.

A digital camera resolution is determined by a digital sensor. The digital sensor indicates a high level of sharpness can be produced through the amount of noise and grain that is tolerated through the lens of the camera. Resolution within the field of digital still and digital movie is indicated through the camera's ability to determine detail based on the distance which is then measured by frame size, pixel type, number, and organization although some DSLR cameras have resolutions limited it almost impossible to not have the proper sharpness for an image. The ISO choice when taking a photo effects the quality of the image as high ISO settings equates to an image that is less sharp due to increased amount of noise allowed into the image along with too little noise can also produce an image that is not sharp. ^[3]

Filter mosaics, interpolation, aliasing

The Bayer filter pattern is a repeating 2x2 mosaic pattern of light filters, with green ones at opposite corners and red and blue in the other two positions. The high proportion of green takes advantage of properties of the human visual system, which determines brightness mostly from green and is far more sensitive to brightness than to hue or saturation. Sometimes a 4-color filter pattern is used, often involving two different hues of green. This provides potentially more accurate color, but requires a slightly more complicated interpolation process.^[4]

Invented in 1976^[5], consumer digital cameras use a Bayer filter mosaic in combination with an optical anti-aliasing filter to reduce the aliasing due to the reduced sampling of the different primary-color images. A demosaicing algorithm is used to interpolate color information to create a full array of RGB image data.

The Bayer filter pattern is a repeating 2x2 mosaic pattern of light filters, with green ones at opposite corners and red and blue in the other two positions. The high proportion of green takes advantage of properties of the human visual system, which determines brightness mostly from green and is far more sensitive to brightness than to hue or saturation. Sometimes a 4-color filter pattern is used, often involving two different hues of green. This provides potentially more accurate color, but requires a slightly more complicated interpolation process.

Sensor resolution

The resolution of a digital camera is often limited by the image sensor that turns light into discrete signals. 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 demosaicing to recreate a full-color image. The number of pixels in the sensor determines the camera's "pixel count". In a typical sensor, the pixel count is the product of the number of rows and the number of columns. Pixels are square and is often equal to 1, for example, a 1,000 by 1,000 pixel sensor would have 1,000,000 pixels, or 1 megapixel. On full-frame sensors (i.e., 24 mm 36 mm), some cameras propose images with 20–25 million pixels that were captured by 7.5–m photosites, or a surface that is 50 times larger. ^[6]

^ Coe, Chris; Weston, Chris (2010-01-01), Coe, Chris; Weston, Chris (eds.), "Section 1 - Perception and the Image", Creative DSLR Photography, Digital Workflow, Oxford: Focal Press, pp. 1–74, doi:10.1016/b978-0-240-52101-5.00001-5, ISBN 978-0-240-52101-5, retrieved 2022-11-09
^ Tarrant, Jon (2007). Understanding Digital Cameras Getting the Best Image from Capture to Output (First ed.). United Kingdom: Elsevier Ltd. pp. 24–26. ISBN 978-0-240-52024-7. Retrieved 21 September 2022.
^ Andersson, Barry (2012). The DSLR filmmaker's handbook : real-world production techniques. Janie L. Geyen. Indianapolis, IN. ISBN 978-1-118-98350-8. OCLC 904979226.{{cite book}}: CS1 maint: location missing publisher (link)
^ Cheremkhin, P A; Lesnichii, V V; Petrov, N V (2014-09-17). "Use of spectral characteristics of DSLR cameras with Bayer filter sensors". Journal of Physics: Conference Series. 536: 012021. doi:10.1088/1742-6596/536/1/012021. ISSN 1742-6588.
^ "StackPath". www.vision-systems.com. Retrieved 2022-10-06.
^ Maitre, Henri (2017). From Photon to Pixel (2nd ed.). Newark: John Wiley & Sons, Incorporated. ISBN 978-1-119-40243-5. OCLC 975225434.

[1] Coe, Chris; Weston, Chris (2010-01-01), Coe, Chris; Weston, Chris (eds.), "Section 1 - Perception and the Image", Creative DSLR Photography, Digital Workflow, Oxford: Focal Press, pp. 1–74, doi:10.1016/b978-0-240-52101-5.00001-5, ISBN 978-0-240-52101-5, retrieved 2022-11-09

[2] Tarrant, Jon (2007). Understanding Digital Cameras Getting the Best Image from Capture to Output (First ed.). United Kingdom: Elsevier Ltd. pp. 24–26. ISBN 978-0-240-52024-7. Retrieved 21 September 2022.

[3] Andersson, Barry (2012). The DSLR filmmaker's handbook : real-world production techniques. Janie L. Geyen. Indianapolis, IN. ISBN 978-1-118-98350-8. OCLC 904979226.{{cite book}}: CS1 maint: location missing publisher (link)

[4] Cheremkhin, P A; Lesnichii, V V; Petrov, N V (2014-09-17). "Use of spectral characteristics of DSLR cameras with Bayer filter sensors". Journal of Physics: Conference Series. 536: 012021. doi:10.1088/1742-6596/536/1/012021. ISSN 1742-6588.

[5] "StackPath". www.vision-systems.com. Retrieved 2022-10-06.

[6] Maitre, Henri (2017). From Photon to Pixel (2nd ed.). Newark: John Wiley & Sons, Incorporated. ISBN 978-1-119-40243-5. OCLC 975225434.

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