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Sunday, October 10, 2010

Chapter 3 - Working with Fonts, Colors, and Graphics (Part1)

Working with Color in HTML

  • Using color will make your web pages:
    -visually interesting
    -eye-catching for the reader

  • HTML identifies a color in one of two ways:
    -by the color value
    -by the color name

  • A color value is a numerical expression that precisely describes a color

  • To have more control and more choices, specify colors using color value

  • Basic Principles of Color Theory

  • Any color can be thought of as a combination of three primary colors: red, green, and blue

  • By varying the intensity of each primary color, you can create almost any color and any shade of color

  • This principle allows a computer monitor to combine pixels of red, green, and blue to create the array of colors you see on your screen

  • Adding the Three Primary Colors

  • Primary color model for light

  • RGB (Red, Green, and Blue) Triplets

  • Software programs, such as your Web browser, define color mathematically

  • Each color is represented by a triplet of numbers, called an RGB triplet, based on the strength of its Red, Green, and Blue component

  • The strength of each of three colors (RGB) is assigned a number from 0 (absence of color) to 255 (highest intensity)

  • White has a triplet of (255,255,255)

  • A Typical Colors Dialog Box

  • In most programs, you make your color choices with visual clues

  • Hexadecimal Values

  • HTML requires color values be entered as hexadecimals

  • A hexadecimal is a number based on base-16 mathematics rather than base-10 mathematics that we use every day
    -hexadecimals include six extra characters: A (for 10), B (for 11), C (for 12), D (for 13), E (for 14), and F (for 15)
    -for values above 15, you use a combination of the 16 characters; 16 is expressed as “10”, 17 is expressed as “11”, and so forth

  • To represent a number in hexadecimal terms, you convert the value to multiples of 16 plus a remainder. For example:
    -21 is equal to (16 x 1) + 5, so its hexadecimal representation is 15
    -the number 255 is equal to (16 x 15) + 15, or FF in hexadecimal format (remember that F = 15 in hexadecimal)

  • Once you know the RGB triplet of a color, the color needs to be converted to the hexadecimal format

  • Using Color Values

  • A palette is a selection of colors

  • When a browser encounters a color that is not in its palette, it attempts to render the color; this is called dithering

  • Use colors from the safety palette to avoid dithering

  • The 216 colors in the safety palette are known as Web-safe colors (0, 51, 102, 153, 204 and 255)

  • Using Color Names

  • Using the basic color names allows you to accurately display them across different browsers and operating systems

  • The list of only 16 colors is limiting to Web designers
    -In response, Netscape and Internet Explorer began to support an extended list of color names

  • The 16 Basic Color Names

  • The 16 basic color names that are recognized by all versions of HTML and XHTML.

  • Partial List of Extended Color Names

  • Partial list of extended color names

  • Defining Foreground and Background Colors

  • Foreground color definition:
    color: color
    color is either the color value or the color name

  • Background color definition:
    background-color: color

  • You can apply foreground and background colors to any page element

  • To define the background color for an entire page:
    Add the bgcolor attribute to the <body> tag

  • To define the text color for an entire page:
    Use the text attribute

  • An example of background and text color changes including the color’s hexadecimal value:
    <body bgcolor=“yellow” text=“#99CCFF”>

  • Working with Fonts and Text Styles

  • A specific font is a font such as Times New Roman, Arial, or Garamond.
    -A specific font needs to be installed on the user’s computer before it can be used

  • A generic font refers to the font’s general appearance
    -Used when none of the specific font can be used

  • Using the <font> Tag

  • The <font> tag allows you to specify the color, the size, and the font to be used for text on a Web page

  • The syntax for the <font> tag is:
    <font size=“size” color=“color” face=“face”> text </font>

  • size attribute allows you to specify the font size of the text

  • color attribute allows you to change the color of individual characters or words

  • face attribute specifies a particular font for a section of text

  • Changing the Font Color

  • The color attribute of the <font> tag allows you to change the color of individual characters or words, by using either a color name or color value
    -for example, to change the color of the word “Aracadium” to the hexadecimal color value 8000C0, you would enter the following HTML tag:
    <font color=“#8000C0”> Arcadium</font>

  • If there is no color specified in the <body> tag, the default colors of the Web browser is used

  • Setting the Font Size

  • The style to change the font size of text within an element:
    font-size: length

  • Absolute units define a font size using one of five standard units of measurement:
    -Millimeters (mm)
    -Centimeters (cm)
    -Inches (in)
    -Points (pt)
    -Picas (pc)

    -1 inch = 72 points = 6 picas

  • Spacing and Indentation

  • Tracking is the amount of space between words and phrases
    -word-spacing: value

  • Kerning is the amount of space between pairs of letters
    -letter-spacing: value

  • Leading is the space between lines of text
    -line-height: length

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