A photo of 4096x2160 pixels means image is a matrix of 4096x2160 cells. Each cell has color depth values of three primary color channels: red/green/blue.
A 8-bit JPEG means it has 0-255 values to represent color where 000 is black and fff is white.
8/12/14/16 bits to hold each red, green, blue tonal values.
JPEG is 8 bit.
- 8 bit: 0-255 => 255^3 => 16.5 million pixels
- 12 bit: 0-4095 => 4095^3 => 68.7 million pixels
- 14 bit: 0-16383 => 16383^3 => 4.397 trillion pixels
- 16 bit: 0-65535 => 65535^3 => 281 trillion pixels
- 24 bit: 0-16777215 => 16777215^3 => 4 sextrillion
- 32 bit: 0-4294967295 => 4294967295^3 => 79 octillion
(See names of large numbers)