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Methods of acquiring digital photographs

Source: licencja: CC 0.

Sposoby pozyskiwania fotografii cyfrowych

You will learn
  • how you can get a digital image,

  • learn how to tell about it in English.

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nagranie abstraktu

Answer the introductory questions.

  1. What does it mean to acquire a photograph?

  2. What are the methods for acquiring a digital image?

  3. How do the colours appear on the digital displaydisplaydisplay?

Task 1

Read the text and then make a short note in a graphic form.

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nagranie abstraktu

People have ever since tried to capture reality that surrounds them. First, they painted on rocks then they produced bas‑reliefs and paintings. Since the end of the 19th century, they have been taking photographs with analogue photographic cameras. At the end of the twentieth century digital photography developed and in short time it practically displaced analogue photography. The principle of producing a digital image is very similar to analogue photography. The difference is the fact that the photosensitive elementphotosensitive elementphotosensitive element such as photographic film has been replaced with a matrixmatrixmatrix of electronic photosensitive elements i.e. a system that contains a large number of light sensors that convert the image into electronic signals. Every element is responsible for registering one image point (i.e. pixel), and the main electronic circuit of the digital camera reads this information while the picture is being taken and saves it to the memory cardmemory cardmemory card in a generally accepted format.

Pictures which are taken using this method look like a small mosaic, with a number of points depending on the number of matrixmatrixmatrix sensors. The effect can be seen immediately on the camera displaydisplaydisplay, in the form of a digital photograph.

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Ilustracja interaktywna przedstawia cztery zdjęcia aparatów fotograficznych. Na pierwszy zdjęciu wyróżniony jest wyświetlacz LCD znajdujący się z tyłu aparatu. Na drugim zdjęciu aparat przedstawiony jest bez obudowy, wyróżniony jest system elektroniczny (ukryty pod obudową). Na trzecim zdjęciu aparat przedstawiony jest bez obudowy, wyróżniony jest czujnik pracy (ukryty pod obudową). Na czwartym zdjęciu wyróżniony jest obiektyw aparatu. Na ilustracji widoczne są numery, a na nich podpisy. 1. LCD screen {audio}, 2. electronic system {audio}, 3. working sensor {audio}, 4. lens {audio}
Electronic system
Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

In the digital camera there is the Bayer's filter (Bayer's grid). It looks like a three‑colour chessboard with red, green and blue fields. Thanks to this, the pixels of the matrix „see” the light in three basic colours: red (R), green (G) and blue (B). Such pixel sensitivity to a particular colour is called the filter matrixmatrixmatrix.

Task 2
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nagranie abstraktu

Open the geogebra applet “Creating colours'” Answer the question: what conditions must be met in order to display different colours on the display?

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Aplet geogebra: Tworzenie nowych kolorów w przestrzeni barw RGB. Poniżej znajduje się galeria będąca wersją alternatywną dla apletu.
Source: GroMar, licencja: CC BY 3.0.
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Source: GroMar, licencja: CC BY 3.0.
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nagranie abstraktu

Miniaturization of elements and constant development of their potentials enabled the construction of very small digital cameras; they are a standard element mounted in mobile phones (smartphones), as well as in tablets or laptops.

Thus, thanks to the development of digital technology, photography has become available to everyone. Taking a picture with the camera which is mounted in a mobile phone is easy and we can see it just after shooting. Currently, the technology of digital image recording (both photography and movie) is common and available to you as well.

It is worth to mention one very important property that digital data has, namely that the date does not change over time. A digitally saved photo or video will be exactly of the same quality after many, many years. In comparison, analogue images lose quality over time. Black and white photos and videos fade, and colour ones lose and change colours. This is an unavoidable process associated with the changes in chemical compounds that disintegrate over time. To protect analogue images which are taken in the past from being completely destroyed, we convert them into digital ones. We can do this with scanners. Scanners can be built in almost the same way as digital cameras, but more accurate images require more advanced constructions. In a typical scanner, the matrixmatrixmatrix has the shape of a strip with photosensitive elements arranged in a row which can register a single line with high accuracy. The strip is moved slowly in front of the scanned object and registers line by line, which in the end gives us a complete picture. To use the scanner you should connect it to the USB connector and install the appropriate software most often sold together with the device.

Then just put a photo or another document in the device, specify the image resolution and decide whether it should be a colour or a black‑and‑white image. After selecting the file format, start scanning. It should be remembered that increasing the image resolution is associated with increasing the size of the file that is recorded on the disk.

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nagranie abstraktu

Acquiring digital images is possible using a digital camera or a scanner. Both devices operate on the basis of light sensors equipped with a matrixmatrixmatrix of colours.

Exercises

Exercise 1
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Wersja alternatywna ćwiczenia: Determine which sentence is true. Możliwe odpowiedzi: 1. In the digital camera, the memory card and matrix are used instead of the photographic film., 2. The pixel is the smallest point in the image., 3. The number of elements from which the image is made depends on the number of matrix points., 4. The Bayer filter should be placed on the camera lens., 5. The basic colours are yellow, red, blue., 6. One of the basic elements of the scanner is the led lamp.
zadanie
Source: GroMar, licencja: CC BY 3.0.
Exercise 2

Match the colour of the filterfilterfilter which is transparent for the following colour of light:

a) red,
b) green,
c) blue,
d) white,
e) violet,
f) yellow.

Exercise 3

Describe in English the scanning method.

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Exercise 4
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Interaktywna gra, polegająca na łączeniu wyrazów w pary w ciągu jednej minuty. Czas zaczyna upływać wraz z rozpoczęciem gry. Jeden ruch to odkrywanie najpierw jednej potem drugiej karty z wyrazem. Każdy wyraz jest odczytywany. Kolejny ruch to odkrywanie trzeciej i czwartej karty. W ten sposób odsłuchasz wszystkie wyrazy. Nawigacja z poziomu klawiatury za pomocą strzałek, odsłuchiwanie wyrazów enterem lub spacją. Znajdź wszystkie pary wyrazów.
Source: Zespół autorski Politechniki Łódzkiej, licencja: CC BY 3.0.

Glossary

image acquisition
image acquisition

pozyskiwanie obrazu

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wymowa w języku angielskim: image acquisition
display
display

wyświetlacz

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wymowa w języku angielskim: display
lens
lens

soczewka

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wymowa w języku angielskim: lens
matrix
matrix

matryca

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wymowa w języku angielskim: matrix
reflex camera
reflex camera

lustrzanka

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wymowa w języku angielskim: reflex camera
filter
filter

filtr

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wymowa w języku angielskim: filter
memory card
memory card

karta pamięci

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wymowa w języku angielskim: memory card
photosensitive element
photosensitive element

element światłoczuły

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wymowa w języku angielskim: photosensitive element
sensor
sensor

czujnik

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wymowa w języku angielskim: sensor
shutter
shutter

migawka

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wymowa w języku angielskim: shutter

Keywords

image acquisitionimage acquisitionimage acquisition

displaydisplaydisplay

lenslenslens

matrixmatrixmatrix

photosensitive elementphotosensitive elementphotosensitive element