What is a digital image?

 

What is an image?

This is an elusive and profoundly philosophical question. But for now, let us start with a simple technical definition.

  • According to: Mishra, Vikash & Kumar, Shobhit & Shukla, Neeraj, 2017, ‘Image Acquisition and Techniques to Perform Image Acquisition’, SAMRIDDHI : A Journal of Physical Sciences, Engineering and Technology.9. 10.18090/samriddhi.v9i01.8333.

 

Image: from Mishra, Vikash & Kumar, Shobhit & Shukla, Neeraj. (2017). Image Acquisition and Techniques to Perform Image Acquisition. SAMRIDDHI : A Journal of Physical Sciences, Engineering and Technology. 9. 10.18090/samriddhi.v9i01.8333.

 

The following videos introduce a series of basic concepts about how digital images are formed:

 

BTW, the PHOTOELECTRIC EFFECT was known in the 19th century.

In 1878, Alexander Graham Bell speculated on the possibilities of translating images via his invention the telephone. In 1879 Punch magazine published an illustration of Edison’s concept of a telephonoscope, an ‘electronic camera obscura’ (a form of steampunk Skype?)
[more info here https://placefacecyberspace.net/2014/11/09/digital-dna/] 

 

 

  • WATCH0:45-2:30: an explanation of the difference between analog and digital
    The Journey to Non-Linear Editing (part 2)
    , 2013, streaming video 20:53 minutes, Youtube, Filmmaker IQ

 

  • WATCH 0:25-2:40; and 5:45-10:50: an explanation of the difference between CCD and CMOS sensors
    The Science of Camera Sensors
    , 2015,  streaming video 13 minutes, Youtube, FilmMaker IQ

 

  • WATCHtil 5:15 How a Pixel Gets Its Colour, 2008, streaming video 6:37 minutes, Youtube, Michael the Maven,
  • WATCHfor an explanation of ISO, SNR and image noise
    How camera sensors pick up light, 2014, streaming video 3:53 minutes, Youtube, CreativeLive
  • WATCH for a more detailed explanation of sensors,  the Bayer Array Filter, and colour interpolation / demosaicing
    Capturing Digital Images, 2015, streaming video 6:05 minutes, Youtube, Computerphile

NOTE: Green give luminance detail

  • BAYER FILTER

image: https://en.wikipedia.org/wiki/Bayer_filter

In the human eye, colour perception is handled by the CONES.

 

 

 

image: https://en.wikipedia.org/wiki/Photoreceptor_cell

 

 

  • WATCH for an introduction to how images are stored as code, bit depth,
    Digital Images, 2015, streaming video 8:15, Youtube, Computerphile

FURTHER READING

 

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