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Fundamentals Of Imaging > Digital Images and Pixels > Flashcards

Digital Images and Pixels Flashcards

1
Q

What are pixels made up of?

A
  • 3 dots - RGB.

- They are rectangular mosaic and all the same size and uniform.

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2
Q

How many pixels in one mega pixel?

A
  • 1 million.
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3
Q

The more pixels the more …?

A
  • Detail.

- Scene it can capture.

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4
Q

What do grey levels do?

A
  • Tell a computer how bright to make each pixel.

- Binary information.

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5
Q

What is a bit?

A
  • A single unit of information and this information is a physical thing.
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6
Q

What is the function of a bit?

A
  • To store a value.
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7
Q

What is a single bit the result of?

A
  • A single decision.
  • Either 0 or 1 / Yes or No / On or Off.
  • Stores the answer to a question.
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8
Q

How are Bits read?

A
  • As numerical values.
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9
Q

What is a byte?

A
  • A combination of 8 bits.
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10
Q

What are “capture devices” capable of?

A
  • How much colour is presented in any 1 given location.
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11
Q

How many different levels of colour can be assigned to each pixel location?

A
  • 256 different levels of colour can be assigned to each pixel location.
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12
Q

What do the 3 colour channels provide?

A
  • Full colour spectrum.
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13
Q

What is each pixel assigned?

A
  • 1 of the 256 different colour levels from each colour channel.
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14
Q

Why are 256 different colour levels sufficient?

A
  • Sufficient to create a smooth transition from light to dark.
  • 8 bits per channel is compatible with the majority of input and output devices.
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15
Q

What is bit depth?

A
  • The number of bits describing and recording tonal and colour variation.
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16
Q

What occurs if we increase the number of bits?

A
  • The more shades of grey we get.
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17
Q

What does the number of bytes and file size depend on?

A
  • The number of pixels.
  • The number of bits.
  • Image compression.
18
Q

What is a fake image?

A
  1. An image not created by a camera.

2. Image originating from a camera but altered to change the meaning.

19
Q

How can we identify fake images?

A
  • Breaks the laws of physics.
  • Differences in images themselves.
  • Image lighting and shadows.
  • Relationship between neighbouring pixels.
20
Q

Why is it difficult to make a fake image look real?

A
  • A computer can’t always determine the grey levels.
  • Antialiasing - edges of pixels adopt transitional colours.
  • Displaying small - not detected with the naked eye.
21
Q

What is a colour channel?

A
  • A mode where image information is stored.

- Present in programs such as PS.

22
Q

What is a capture device?

A
  • Measures the amount of colour in 1 location.
23
Q

What are 8 bits sufficient for?

A
  • A good quality image.
24
Q

What does a higher bit depth result in?

A
  • Greater potential for colour accuracy.
25
Q

Give 5 image file formats.

A
  1. RAW.
  2. JPEG - point photographic experts group.
  3. TIFF - tagged image file format.
  4. PS document.
  5. GIF - a lossless format for image files that supports both animated and static images.
26
Q

What is 1 byte?

A

8 bits.

27
Q

What is 1 KB?

A

1024 bytes.

28
Q

What is one MB?

A

1024 KB.

29
Q

What is one GB?

A

1024 MB.

30
Q

What is a RAW image?

A
  • An image with more than 8 bits per channel.
  • Useful for extensive tonal / colour correction.
  • Is more mouldable than JPEG.
  • A raw file is the image as seen by the camera’s sensor. - - Think of it like unprocessed film. Rather than letting the camera process the image for you, turning it into a JPEG image, shooting in raw allows you to process the image to your liking.
31
Q

What is a colour gamut?

A
  • Range of colours within spectrum available to a particular device.
32
Q

What is a colour gamut dependant on?

A
  • Paper quality.
  • Colourant used.
  • Gamut of document.
33
Q

What is resolution?

A
  • Specifies size of a pixel (a dot of coloured light on monitor).
34
Q

What 2 resolutions are often in play in a document?

A
  • Digital file resolution.

- Output device resolution.

35
Q

What is overall resolution dependant on?

A
  • Capture size.
  • Image resolution.
  • Monitor resolution.
  • Printer resolution.
36
Q

What is meant by dpi and ppi?

A

Dpi - dots per inch.

Ppi - pixels per inch.

37
Q

Why might we rescale an image?

A
  • For the intended output.

- Before retouching and enhancing.

38
Q

What is meant by constrain proportions?

A
  • The height and width of a document is linked.
39
Q

What is meant by resampling?

A
  • File size increases or decreases to accommodate changes.
  • Pixels are added.
  • This does not affect the pixel dimensions.
40
Q

What is meant by downsampling?

A
  • Decreasing the number of pixels.

Fundamentals Of Imaging (10 decks)

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