## Hertz (Hz)

The hertz (symbol: Hz) is a unit used to measure the frequency of electromagnetic waves.

https://en.wikipedia.org/wiki/Hertz

## Hertz (Hz)

The hertz (symbol: Hz) is a unit used to measure the frequency of electromagnetic waves.

An hexadecimal number (hex number) has a base (radix) of 16 whilst a decimal system of notation has a base of 10.

• The familiar decimal system of notation uses nine distinct symbols 0 – 9. It then adds columns to the right to denote 10’s, 100’s etc.
• A hexadecimal system of notation uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F (or a, b, c, d, e, f) to represent values ten to fifteen. Further columns are added on the right to denote 16’s, 256’s etc.
• A hexadecimal triplet is a six-digit, three-byte hexadecimal system of notation used in programming and software applications (graphic design, web development, photography) to represent colours. The bytes represent the red, then green and then blue components of a colour.
• Each byte represents a number in the range 00 to FF in hexadecimal notation (0 to 255 in decimal notation).
• The hash symbol (#) is used to indicate hex notation.
• Red = #FF0000
• Yellow = #FFFF00
• Green = #00FF00
• Cyan = 00FFFF
• Blue = #0000FF
• Magenta = #FF00FF
• The sequence of hexadecimal values between 1 and 16 = 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E and F.
• The sequence of hexadecimal values between 17 and 32 = 10,11,12,13,14,15,16,17,18,19,1A,1B,1C,1D,1E and 1F.

An hexadecimal number (hex number) has a base (radix) of 16 whilst a decimal system of notation has a base of 10.

• The familiar decimal system of notation uses nine distinct symbols 0 – 9. It then adds columns to the right to denote 10’s, 100’s etc.
• A hexadecimal system of notation uses sixteen distinct symbols, most often the symbols 0–9 to represent values zero to nine, and A, B, C, D, E, F (or a, b, c, d, e, f) to represent values ten to fifteen. Further columns are added on the right to denote 16’s, 256’s etc.
• A hexadecimal triplet is a six-digit, three-byte hexadecimal system of notation used in programming and software applications (graphic design, web development, photography) to represent colours. The bytes represent the red, then green and then blue components of a colour.
• Hexadecimal triplets can be used to represent 256 x 256 x 256 different colours.
• Each byte represents a number in the range 00 to FF in hexadecimal notation (0 to 255 in decimal notation).
• The hash symbol (#) is used to indicate hex notation.
• Red = #FF0000
• Yellow = #FFFF00
• Green = #00FF00
• Cyan = 00FFFF
• Blue = #0000FF
• Magenta = #FF00FF
• The sequence of hexadecimal values between 1 and 16 = 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E and F.
• The sequence of hexadecimal values between 17 and 32 = 10,11,12,13,14,15,16,17,18,19,1A,1B,1C,1D,1E and 1F.
• The sequence then continues to increment the two digits up to 256.

## Horizontal cell

Retinal horizontal cells are laterally interconnecting neurons located in the retina of the human eye.

• Horizontal cells are connected to the rod and cone cells by synapses, so horizontal cells are called laterally interconnecting neurons.
• Horizontal cells help to integrate and regulate of photoreceptor cells, cleaning up and globally adjusting signals passing through bipolar cells towards the region containing ganglion cells.
• An important function of horizontal cells is enabling the eye to adjust to both bright and dim light conditions. They achieve this by providing feedback to rod and cone photoreceptors about the average level of illumination falling onto specific regions of the retina.
• If a scene contains objects that are much brighter than others, then horizontal cells are believed to prevent signals representing the brightest objects from dazzling the retina and degrading the quality of information.

https://en.wikipedia.org/wiki/Retina_horizontal_cell

## HSB colour model

HSB is a popular colour model that provides an intuitive way to select and adjust colours in software applications used for graphic design, web development and photography.

• In the implementation of HSB used in Adobe Illustrator CC, brightness and saturation are used to alter the intensity of a hue. In this way:
• H=00, S=100%, B= 100% produces a fully saturated primary red hue with maximum intensity.
• H=00, S=100%, B= 50% produces a darker shade of a fully saturated primary red hue.
• H=00, S=50%, B= 100% produces a lighter tint and thus a partially de-saturated primary red hue.
• Selecting an RGB swatch 255,0,0 (#FF0000) as a stroke or fill for a selected object.
• Double-clicking the swatch for the selected object, selecting HSB in the Color panel menu and reducing saturation for tints or reducing brightness for shades.
• Or selecting the Color Guide panel with an object selected and selecting
• The brightness of a hue is reduced on a display device by reducing the amplitude of the RGB colours produced by each pixel.
• The brightness of a hue is reduced on a digital printer by increasing the amount of black mixed with red ink.

## HSB colour values

Definition

HSB colour values (codes) are decimal triplet used in software applications to represent colour.

HSB refers to hue, saturation and brightness.

Values applied to each of these three parameters can be used to specify any colour within the RGB colour models used by display devices and printers.

Explanation

In the implementation of the HSB colour model used in Adobe Illustrator CC:

Hue is represented in degrees from 00 to 3590 corresponding with locations on the circumference of a colour wheel.

Saturation is represented as a percentage where100% denotes a fully saturated hue and 0% denotes a fully desaturated hue.

Brightness is represented as a percentage where 100% denotes a hue at maximum luminance and 0% denotes the darkest possible version of a hue.