28. Bit depth drastically affects file size
24 bit color
16 millioncolors
1.55 MB
8 bit color
256 colors
518k
8 bit
gray scale
256 shades
of gray
518k
1 bit dithered
image
64k
38. Example of an image at 72-ppi and 300-ppi
• 72 ppi = 72 pixels high x 72 pixelswide = 5184 pixels in a square inch
• 300 ppi = 300 pixels high x 300 pixels wide = 90,000 pixels in a square inch
39. Color Mode
• A color mode determines the color model used to display and print
images.
• Common models include
– RGB (red, green, blue)
– CMYK (cyan, magenta, yellow, black)
– …
40. RGB model
• RGB model used for lighting, video, and monitors
• So, computer’s monitor only has 3 colors
Red
Green
Blue
41. CMYK model
• The CMYK model is based on the light-absorbing quality of ink
printed on paper.
73. 1. "Image of George Washington"
2. "George Washington, the first president of the United States"
3. An empty alt attribute (alt="") will suffice.
4. "George Washington"
74. 1. An empty alt attribute (alt="") will suffice.
2. "Wikipedia entry for George Washington"
3. "Read More"
4. "George Washington"
75. 1. "George Washington"
2. "Painting of George Washington"
3. "Painting of George Washington crossingthe Delaware River"
4. "Painting of George Washington crossingthe Delaware River. Swirling waves surround the
boat where the majestic George Washington looks forward out of the storm and into the
rays of light across the river as he leads his wary troops to battle."
76. 1. "Employment Application"
2. "PDF File"
3. "PDF icon"
4. The content of the image is presented in context, so (alt="") is
appropriate.
85. การลงรหัสที่ไม่ถูกต้อง
<p><font size=“+3”><b>This is a heading</b></font></p>
<p>Blah blah blah</p>
<p><font size=“+3”><b>This is another heading</b></font></p>
<p>Blah blah blah</p>
<p><font size=“+2”><b>A sub-section</b></font></p>
<p>Blah blah blah</p>
86. การลงรหัสที่ถูกต้อง
Use markup and style sheets and do so properly
<h1>This is a heading</h1>
<p>Blah blah blah</p>
<h1>This is another heading</h1>
<p>Blah blah blah</p>
<h2>A sub-section</h2>
<p>Blah blah blah</p>
Outline:
•This is a heading
•This is another heading
–A sub-section