Pixel & resolution
What is the smallest individual part of a digital image called?
A pixel
What do the letters R, G and B stand for?
Red, Green and Blue
What does "resolution" measure?
The number of pixels that make up an image (width × height)
What is the RGB value range for each colour channel?
0 To 255
An image is 1000 × 500 pixels. Calculate the total number of pixels and state the unit this is measured in.
500,000 Pixels
State the RGB value for black and explain what it means for each channel to be 0.
RGB(0, 0, 0); 0 means none of that colour's light is present
State what form of data computers use to store image information, and explain why this form is used.
Binary; because computers can only process and store data as 0s and 1s (on/off electronic signals)
State how many possible colours 8-bit colour depth can represent, and show the calculation.
256; because 2⁸ = 256
Explain why a 100×100 image looks blurry when enlarged, and state what happens to file size as resolution increases.
Fewer pixels mean less detail is recorded, so enlarging stretches each pixel and shows blocky/blurry results; increasing resolution increases the number of pixels, which increases file size
A 24-bit RGB image is 1920 × 1080 pixels. Calculate the uncompressed file size in bytes and explain what "24-bit" refers to.
1920 × 1080 × 24 = 49,766,400 bits ÷ 8 = 6,220,800 bytes (≈6.2 MB); 24-bit means 8 bits are used for each of the red, green and blue channels