Hex Representation of Base Ten Numbers in Java

Creation PDF417 in Java Hex Representation of Base Ten Numbers

Hex (Base 16)

0 1 2 3 4 5

(continued)

Table 1-2 (continued)

Decimal (Base 10)

6 7 8 9 10 11 12 13 14 15

Hex (Base 16)

The ordinary digits 0 9 are the same in hex as they are in base 10, but the values from 10 15 (base ten) are represented by alphabetic characters in hexadecimal You re very used to seeing the value 10 as equal to the number of fingers on both hands, but that s not always the case when you start messing around with numbering systems like we re doing here 10 simply means one of the current base Up to now, you may have never used any base but base ten, but all that changes here 10 is ten in base ten, but in base two, 10 means two In base eight, 10 means eight, and in base sixteen, 10 means sixteen This is important because when you want to talk about the number of digits on your hands in hex, you can t use the familiar notation 10, because in hex 10 means sixteen We need a single-digit value to represent ten, so computer scientists legislated themselves out of this mess by borrowing letters Ten is A, eleven is B, and fifteen is F If all this math theory is making you dizzy don t worry I show in the next section some shortcuts for creating great colors using this scheme For now, though, here s what you need to understand to use hex colors: A color requires six digits of hex A pixel requires three colors, and each color uses eight digits of binary Two digits of hex cover each color Two digits represent red, two for green, and finally two for blue Hex numbers usually begin with a pound sign To warn the browser that a value will be in hexadecimal, the value is usually preceded with a pound sign (#) So, yellow is #FFFF00 Working with colors in hex may seem really crazy and difficult, but it has some important advantages:

Precision: Using this system gives you a huge number of colors to work with (over 16 million, if you really want to know) There s no way you could come up with that many color names on your own Well, you could, but you d be very very old by the time you were done Objectivity: Hex values aren t a matter of opinion There could be some argument about the value of burnt sienna, but hex value #666600 is unambiguous Portability: Most graphic editors use the hex system, so you can pick any color of an image and get its hex value immediately This would make it easy to find your cat s eye color for that online shrine Predictability: After you understand how it works, you can take any hex color and convert it to a value that s a little darker, a little brighter, or that has a little more blue in it This is difficult to do with named colors Ease of use: This one may seem like a stretch, but after you understand the Web-safe palette, which I describe in the next section, it s very easy to get a rough idea of a color and then tweak it to make exactly the form you re looking for

A long time ago, browsers couldn t even agree on what colors they d display reliably Web developers responded by working within a predefined palette of colors that worked pretty much the same on every browser Today s browsers have no problems showing lots of colors, but the so-called Websafe color palette is still sometimes used because it s an easy starting point The basic idea of the Web-safe palette (shown in Table 1-3) is this: Each color can have only one of the following values: 00, 33, 66, 99, AA, CC, or FF 00 is the darkest value for each color, and FF is the brightest The primary colors are all made of 0s and Fs: #FF0000 is red (all red, no green, no blue) A Web-safe color uses any combination of these values, so #33AA00 is Websafe, but #112233 is not

Table 1-3