BH: SCRAP. Two pages on... hexadecimal??
We can pack four bits (binary digits) into one hexadecimal digit because 16 is a power of two (16 = 24). So, a group of four bits represents a value between 0 and 15, and one hex digit also represents values from 0-15 (using 0-9 and A-F). This makes it easier to translate between binary and hex than between other bases.
Hexadecimal is an abstraction over binary: we use hexadecimal to abbreviate binary in a more readable way.
You can create a table like this whenever you need one.
| binary | hex |
|---|---|
| 00002 | 016 |
| 00012 | 116 |
| 00102 | 216 |
| 00112 | 316 |
| 01002 | 416 |
| 01012 | 516 |
| 01102 | 616 |
| 01112 | 716 |
| 10002 | 816 |
| 10012 | 916 |
| 10102 | A16 |
| 10112 | B16 |
| 11002 | C16 |
| 11012 | D16 |
| 11102 | E16 |
| 11112 | F16 |
To translate a binary numeral (for example, 11010111012) to hexadecimal, start by splitting it into groups of four bits, from right to left (like this: 11 0101 1101).
Then determine the value of each group and write the corresponding hex digit (look it up on the table at right).
For example: 112 = 316, 01012 = 516, and 1101 = D16. So, 11010111012 = 35D16.
To translate a hex numeral (like 4E116) to binary, write each hex digit as a group of four bits (including any leading zeros).
For example: 416 = 01002, E16 = 11102, and 116 = 00012. So, 4E116 = 0100111000012 or just 100111000012 because we can drop the leading zero once the digits are all in their places.
A pixel is a single dot of color on the computer screen. It's short for "picture element."
Computers have several ways of representing color depending on the purpose. For example, three-color RGB (red, green, blue) is used for screen display, and four-color CMYK (cyan, magenta, yellow, black) is used for printing. On a computer screen, each pixel that makes up a picture is assigned an RGB color code that defined by the intensity of red, green, and blue in that color. These three color intensities each range from 0 to 255 (one byte is used for each of the three colors), which is 00 to FF in hex notation.
If (R, G, B) = (128, 0, 255), the color is purple: some red and as much blue as possible, but no green at all. If all three colors are as bright as possible (all are 255), we see white; if they are as dark as possible (all are 0), we see black. Instead of writing (255, 255, 255) for white and (128, 0, 255) for purple, we often use hex notation: FFFFFF and 8000FF. And this color is red 255, green 127, and blue 0, which is FF7F00 in hex.
Sometimes a fourth number is used to represent the color transparency, like the ghost effect you used in your very first BJC project on Unit 1 Lab 1 Page 3: Make It a Game.
RGB works well for lights, such as the tiny lights (pixels) in your computer screen, so it is great for computers. But it's not good for printers: no combination of Red, Green and Blue sprayed on paper would quite make black, zero of each would leave the paper white (not black), and artists know that mixing red and green paint does not make yellow (but that's how you make yellow with light: FFFF00). Ink or paint colors are measured in CMYK: Cyan, Magenta, Yellow, and Black. And some colors such as brown and brick-red (darker than pure red) are hard to figure out in RGB units, even for display in lights. Another color system is called HSB, for hue, saturation, brightness.
Snap!'s system is similar to HSB. "Pen color" is hue (location on the rainbow), and "pen shade" is more or less saturation (zero means black, 100 means full rainbow color).
