# Computing - Images

> Source: https://ollybritton.com/notes/a-level/computing/topics/images/ · Updated: 2020-10-13 · Tags: computing, school, safe-to-post-online

##### In one sentence, how does a camera work??
Approximating a real image by cutting it up into a grid using a light sensor.

##### How is the grid of colour converted into binary in a camera??
Using an analogue-to-digital converter.

##### What is a bitmap??
A grid of pixels.

##### What's another word for raster graphics??
Bitmap graphics.

##### What is a common bitmap file type??
* BMP
* JPG
* GIF
* PNG
* TIF

##### What is special about a BMP file??
It is uncompressed.

##### What is the definition of resolution??
$$
\text{width} \times \text{height}
$$

##### What's another name for $1,000,000$ pixels??
1 megapixel.

##### Why doesn't resolution affect the physical size of an image??
Because the size of each pixel in the image can grow or shrink to fit the size of the screen.

##### What is bit depth in image representation??
The amount of bits allocated to each pixel.

##### What is the formula for image file size??
$$
\text{pixels} \times \text{bit depth}
$$

##### What's an example of image metadata??
* Creation date
* Width and height of image
* Colour/bit depth
* Geolocation

##### Where is metadata stored??
In the same file as the image data.

##### What's a consequence of storing metadata in an image??
It makes the file bigger.

##### How do vector graphics work??
Describing images as combinations of geometrical objects.

##### What is the advantage of vector graphics??
They do not lose quality when scaled.

##### What is the downside of vector graphics??
It's hard to represent complex graphics, like a portrait.

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