I’ve never been able to grasp how it is possible to take photos or videos. I know in school we were taught about it but it never clicked.
In: Technology
Digital cameras work by using a lens to focus light down onto a sensor. when you focus the light you form an image of what the lens is seeing, so you can imagine it as a picture of what the lens sees being projected onto the sensor.
A digital sensor these days will be a CMOS sensor which works by converting photons that hit it into a charge, then at the end of the exposure it counts how much charge is in each pixel. More charge means more light. This gets converted into a digital image which is essentially a map of how bright the image on the sensor was at each pixel.
The way we get colour is by using a pattern of red, green and blue filters in front of the pixels, so 1/4 of the pixels only detect red light, 1/4 only detect blue and 1/2 only detect green. Now when we get the map of how bright the image is we can do some guesswork to estimate the colour of each pixel based on its colour/brightness and the colour/brightness of the surrounding pixels.
Video is the exact same but you take many pictures and string them together, normally you have to make some compromises to how much information you store by having these images at a lower resolution and using less numbers to represent brightness.
We invented stuff that’s bothered by light. We measure *how* that light is disturbed into numbers that we can use to draw that picture again. Multiple times per second for movies.
Very simply traditional chemical photography is based on focusing light onto a film covered in tiny light sensitive crystal granules, when exposed to light the optical properties of the granules change. Early film formulations had a long exposure time meaning it took more time for the chemical reactions in the film to take place therefore people had to remain very still when being photographed or the image would be blurry.
Over time formulations with shorter exposure times were developed eventually allowing for motion pictures in which 24 images could be taken per second on a strip of film, colour photography worked by incorporating 3 layers of film sensitive to light at red, green & blue wavelengths.
Digital photography again very simply works by focusing an image onto a sensor with a matrix of light senstive components that are logged and reset multiple times a second in the case of digital video with the sensor data then being stored and processed electronically. Colour digital photography uses an RGB filter to focus light of different wavelenghts on different areas of the sensor grid which can then be combined with processing to create a colour image, higher-end cameras may use 3 separate photosensors for red, green & blue with light directed at each with a prism.
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