Start learning with our library of video tutorials taught by experts. Get started

Dreamweaver CS5 Essential Training
Watching:

Understanding image types


From:

Dreamweaver CS5 Essential Training

with James Williamson

Video: Understanding image types

When creating images for the Web, it is important to understand which types of images you can use online and when it's appropriate to use one over the other. Determining which file type to use is usually a decision made after considering file size and functionality. For online graphics, your goal is always going to be obtaining the best image quality in the smallest file size possible. Understanding how file types are compressed and best practices for creating them will help you keep your image quality high or keeping file size down.
Expand all | Collapse all
  1. 2m 57s
    1. Welcome
      1m 8s
    2. Using the exercise files
      1m 49s
  2. 7m 50s
    1. What is Dreamweaver?
      3m 16s
    2. Learning web design
      2m 22s
    3. Current web standards
      2m 12s
  3. 43m 9s
    1. The Welcome screen
      4m 5s
    2. Windows and Mac interface differences
      2m 23s
    3. The Application toolbar
      4m 7s
    4. The Document toolbar
      4m 40s
    5. Arranging panels
      8m 19s
    6. Managing workspaces
      7m 32s
    7. The Properties Inspector
      5m 54s
    8. The Insert panel
      6m 9s
  4. 25m 45s
    1. Basic site structure
      3m 11s
    2. File naming conventions
      1m 49s
    3. Defining a new site
      4m 35s
    4. Managing sites
      4m 51s
    5. Managing files and folders
      6m 36s
    6. Working with browsers
      4m 43s
  5. 27m 21s
    1. Creating new documents
      5m 16s
    2. New document preferences
      3m 6s
    3. Setting accessibility preferences
      4m 56s
    4. Working with starter pages
      3m 46s
    5. Managing starter pages
      10m 17s
  6. 30m 2s
    1. Basic tag structure
      2m 15s
    2. Adding structure to text
      8m 20s
    3. Creating lists
      9m 59s
    4. Getting text into Dreamweaver
      5m 59s
    5. Importing Word documents
      3m 29s
  7. 1h 17m
    1. Understanding style sheets
      2m 16s
    2. The anatomy of a CSS rule
      1m 48s
    3. Setting CSS preferences
      6m 36s
    4. The CSS Styles panel
      10m 2s
    5. Controlling CSS through the Properties Inspector
      5m 14s
    6. Using the Code Navigator
      7m 21s
    7. Using CSS Enable
      6m 45s
    8. Understanding element selectors
      8m 11s
    9. Understanding class selectors
      8m 49s
    10. Understanding ID selectors
      5m 59s
    11. Understanding descendant selectors
      6m 51s
    12. Attaching external style sheets
      7m 44s
  8. 1h 47m
    1. Working with units of measurement
      7m 11s
    2. Declaring font families
      9m 39s
    3. Controlling font sizing
      9m 9s
    4. Controlling weight and style
      8m 0s
    5. Controlling line height
      8m 29s
    6. Controlling vertical spacing with margins
      12m 3s
    7. Controlling spacing with padding
      5m 39s
    8. Aligning text
      8m 26s
    9. Transforming text
      5m 36s
    10. Writing global styles
      15m 42s
    11. Writing targeted styles
      17m 37s
  9. 1h 32m
    1. Understanding image types
      5m 3s
    2. Managing assets in Dreamweaver
      12m 51s
    3. Setting image accessibility preferences
      4m 20s
    4. Setting external image editing preferences
      3m 52s
    5. Placing images on the page
      7m 37s
    6. Photoshop integration
      5m 54s
    7. Modifying Smart Objects
      5m 51s
    8. Alternate Photoshop workflows
      8m 8s
    9. Modifying image properties
      11m 14s
    10. Styling images with CSS
      7m 11s
    11. Using background graphics
      9m 3s
    12. Positioning background graphics
      11m 6s
  10. 55m 16s
    1. Link basics
      3m 37s
    2. Setting site linking preferences
      2m 14s
    3. Creating links in Dreamweaver
      11m 1s
    4. Absolute links
      5m 8s
    5. Using named anchors
      11m 19s
    6. Linking to named anchors in external files
      2m 44s
    7. Creating an email link
      5m 24s
    8. Creating CSS-based rollovers
      13m 49s
  11. 1h 34m
    1. CSS structuring basics
      2m 56s
    2. The Box Model
      13m 21s
    3. Understanding floats
      6m 53s
    4. Clearing and containing floats
      8m 56s
    5. Using relative positioning
      4m 8s
    6. Using absolute positioning
      7m 18s
    7. Creating structure with div tags
      12m 7s
    8. Styling basic structure
      10m 34s
    9. Creating a two-column layout
      10m 37s
    10. Using Live View and CSS Inspect
      7m 51s
    11. Using Browser Lab
      9m 39s
  12. 56m 22s
    1. Reviewing table structure
      7m 41s
    2. Importing tabular data
      5m 13s
    3. Creating accessible tables
      9m 56s
    4. Using thead and tbody tags
      4m 0s
    5. Basic table styling
      8m 45s
    6. Styling table headers
      7m 52s
    7. Styling column groups
      4m 22s
    8. Creating custom table borders
      5m 1s
    9. Styling table captions
      3m 32s
  13. 1h 43m
    1. How forms work
      3m 0s
    2. Reviewing form design
      3m 2s
    3. Creating accessible forms
      7m 33s
    4. Setting form properties
      4m 6s
    5. The fieldset and legend tags
      4m 32s
    6. Inserting text fields
      5m 58s
    7. Inserting list menu items
      5m 26s
    8. Inserting checkboxes
      7m 50s
    9. Inserting radio button groups
      6m 22s
    10. Inserting text areas
      4m 12s
    11. Inserting submit buttons
      3m 37s
    12. Basic form styling
      12m 0s
    13. Form element styling
      8m 52s
    14. Styling form layout
      11m 49s
    15. Adding form interactivity
      2m 47s
    16. Using Spry validation widgets
      12m 49s
  14. 1h 23m
    1. Planning for templates
      10m 51s
    2. Creating a new template
      10m 37s
    3. Using editable attributes
      13m 43s
    4. Creating optional regions
      6m 23s
    5. Creating new pages from a template
      9m 17s
    6. Applying templates to existing pages
      6m 9s
    7. Working with nested templates
      7m 56s
    8. Working with repeating regions
      12m 58s
    9. Modifying templates
      5m 41s
  15. 40m 14s
    1. Behaviors overview
      3m 47s
    2. Hiding and showing elements
      9m 18s
    3. Spry overview
      4m 4s
    4. Using Spry widgets
      11m 36s
    5. Adding Spry effects
      3m 6s
    6. Using the Widget Browser
      8m 23s
  16. 28m 18s
    1. Inserting Flash files
      5m 4s
    2. Setting properties for Flash
      6m 27s
    3. Dreamweaver and Flash integration
      6m 6s
    4. Encoding Flash video
      6m 10s
    5. Adding Flash video
      4m 31s
  17. 45m 28s
    1. Running site-wide reports
      6m 33s
    2. Checking for broken links
      5m 41s
    3. Checking for browser compatibility
      8m 3s
    4. Adding remote servers
      8m 0s
    5. Uploading files
      7m 20s
    6. Managing remote sites
      9m 51s
  18. 34s
    1. Goodbye
      34s

Watch this entire course now—plus get access to every course in the library. Each course includes high-quality videos taught by expert instructors.

Become a member
Please wait...
Dreamweaver CS5 Essential Training
15h 22m Beginner Apr 30, 2010

Viewers: in countries Watching now:

In Dreamweaver CS5 Essential Training, Adobe Certified Instructor James Williamson explores the tools and techniques of Dreamweaver CS5, Adobe's web design and development software. This course covers both the ins and outs of Dreamweaver, as well as recommended best practices for crafting new web sites and files, the fundamentals of HTML and CSS, and how to ensure clean and accessible code. The course also includes how to use tools in Dreamweaver to create and style web pages, manage multiple sites, and add user interactivity with widgets and scripting. Exercise files are included with the course.

Topics include:
  • Defining and structuring a new site
  • Creating new web documents from scratch or from templates
  • Adding and formatting text
  • Understanding style sheet basics
  • Placing and styling images
  • Creating links to internal pages and external web sites
  • Controlling page layout with CSS
  • Building and styling forms
  • Reusing web content with templates
  • Adding interactivity
  • Working with Flash and video
Subject:
Web
Software:
Dreamweaver
Author:
James Williamson

Understanding image types

When creating images for the Web, it is important to understand which types of images you can use online and when it's appropriate to use one over the other. Determining which file type to use is usually a decision made after considering file size and functionality. For online graphics, your goal is always going to be obtaining the best image quality in the smallest file size possible. Understanding how file types are compressed and best practices for creating them will help you keep your image quality high or keeping file size down.

Before we discuss how Dreamweaver manages images, let's first examine the three file types you'll be using when creating your Web graphics: JPGs, GIFs and PNGs. JPG is short for Joint Photographic Experts Group and is a standard that has been around in one form or another since about 1992. The JPG file format allows you to create images with millions of colors, which makes it an ideal choice for photographs or images with subtle color differences. The downside to using JPGs is that, when saved, a lossy compression is used to save file size, resulting in image data being thrown away.

Although, you can choose the amount of compression when saving a JPG, data is discarded each and every time it is saved. For that reason, it's a good idea to save your original image in a file format other than JPG and simply overwrite the original JPG when a change is made to the source graphic. Also, JPGs do not support transparency or animation, which may make them unsuitable for certain uses. The GIF, short for Graphics Interchange Format, file format was first introduced by CompuServe in 1987 and quickly became a staple for online graphics.

Unlike the 24-bit JPG format, GIFs are 8- bits, which limits the color palette of GIF files to a maximum of 256 colors. Now GIFs do have the advantage of using a lossless compression format, which reduces file size without damaging image quality. GIFs also support animation and transparency, making them the favorite file format of icons and dancing babies worldwide. Due to their limited palette, GIFs are not well suited for images that have subtle tonal shifts or a wide range of color.

They are however, ideal for smaller thumbnails or images that have large areas of solid colors. PNG stands for Portable Network Graphics and owes its existence to the very curious case of Unisys, holding the patent for the compression algorithm used in GIFs in 1995. PNGs were designed to replace GIFs and share many of the GIF file format strings, but they have added functionality. PNGs, like GIFs, support transparency and use lossless compression to achieve smaller file sizes.

Unlike GIFs however, PNGs files are 24- bit graphics, which allow them to display millions of colors and subtle tonal shifts without using dithering or banding. So which file format should you use? Well, honestly it depends on each individual image and how that image is going to be used within your files. As a general rule, JPGs are best for large images and photographs, specifically images that have lots of color and detail. High compression settings can cause serious image degradation, so it's best to compare image quality and compression for each image before deciding on an export setting for your JPG.

As a best practice, remember to keep a source image for your JPG so that you're not editing and overwriting the JPG itself. JPG image quality degrades each time it saved, and this could result in an unusable image over time if saved over and over itself. GIFs are great for thumbnails, small icons or images that contain large areas of solid colors. They're also a standard image type for any image needing transparency or limited animation. Now keep in mind that GIFs do have a limited palette, so complex images with lots of color or tonal shifts like gradients, can suffer when saved as GIFs.

PNGs also have all the advantages of GIFs, without the liabilities. PNGs feature full 24-bit support, so millions of colors can be saved along with transparency. The downside to using PNGs is they tend, on average, to be a little bit bigger than GIFs and JPGs, so heavy use of them throughout your site tends to add to the site's overall weight. Older browsers support was spotty at best. So for Legacy sites or sites that target older browsers, PNGs files are not a good choice. Also, Internet Explorer 6 did not support transparency for PNGs, resulting in having to write some pretty fancy CSS to force PNG transparency support.

As a whole, PNG usage is rapidly increasing on the Web, but if used, the file format is usually used to supplement graphics on sites or to do things that JPGs and GIFs just can't. In the end, the file format you use for Web graphics is totally up to you. Knowing more about the file types and their capabilities will help you make an informed choice.

Find answers to the most frequently asked questions about Dreamweaver CS5 Essential Training.


Expand all | Collapse all
Please wait...
Q: After creating a website following the instructions in the course, the header background graphic appears correctly in all browsers except Internet Explorer 6 and Internet Explorer 7.  The graphic works properly in IE 8. What can be done to make the graphics appear in IE 6 and IE 7?
A: To make the header background graphic appear, wrap the header div tag in another div tag and give it an ID like “mainHeader.” The problem stems from a bug in Internet Explorer that prevents the browser from dealing with absolutely positioned elements that are right next to relatively positioned elements.  Following the steps above should solve the problem.
Q: In the tutorial, the author links the Tool Tip to the word "More" at the bottom of the thumbnail photo field. I can't figure out how to place the <a> "More" on the thumbnail photo field.
A: In the example, there is a paragraph that wraps an <img> tag and the word "More," which is surrounded by an anchor tag (<a>). The author uses CSS to make sure the parent div tag of the thumbs floats to the left, and is only wide enough for the image. This causes the link text to break down onto another line. Then, the instructor uses CSS to align the link text to the right of the <img>. The link itself is a void JavaScript function, ( javascript();). This gives you a "dummy" link without returning you to the top of the page as the "#" dummy link tends to do.
If you were manually typing the text in, you could select the image, hit the right arrow button, and begin typing. The text should then appear on screen.
Q: In this movie, you are making changes to the HTML in order to customize the text layout on your page (i.e. h1, h2, and h3 tags as well as strong and em tags). I'm wondering why you are not using CSS to do this (i.e. font-size, font-weight). Do you typically use one method, or is it customary to do use both in a layout, and if so, what guidelines would you suggest to determine which to use when?
A: We modify the page's structure through the use of h1, h2, and other heading tags. So when we are choosing heading levels, we're not concerning ourselves with typography; we're establishing page structure. A heading is chosen to denote the level of importance for the heading, not typography.
CSS should always be used for presentation, not HTML.
Q: In the “Understanding ID selectors” movie, the author states that only one ID tag can be used per page, but then he adds two ID tags. Can you please clarify this for me?
A: You can use as many IDs per page as you wish. They just must all use a unique name. Therefore if you assign an element the ID of "header" no other element on THAT page may use the same ID.
Q: I noticed that in this course, the instructor uses this code on his CSS external sheet: @charset "UTF-8"; I was under the impression that this code wasn't necessary. The W3.org site is unclear on the matter. Is it necessary? Is it a best practice? Is it an older form of CSS?
A: The characterset attribute is added automatically by Dreamweaver, and there’s no practical reason to remove it. While it's not needed (the HTML page should indicate which encoding to use for the page) it is helpful if the CSS file is ever imported or used on a page where the characterset isn't specified. Think of it as a safety net for characterset encoding. Not necessary, but not harmful either.
Q: I need to add captions below images that I insert in pages of text. I played all the lessons in Chapter 5 (Adding Text and Structure) but none dealt with captions. I hope the author has an answer or can refer me to a source.
A: In HTML 4 and XHTML 1 (which is what Dreamweaver CS5 uses by default), there wasn't really a way to add captions below your photos. Most web authors would "fake" captions by having paragraphs of text below their images and using CSS to position and style the captions in the desired manner. Many would use a class such as .imgCaption to control the styling. To do this you would essentially position the text underneath the image through CSS (often by grouping the image and the paragraph in a div tag) and italicizing the text.

However in HTML5, there are new elements that allow us to associate images and their captions, the figure and figcaption element. Our author James Williamson just finished a course on HTML5: Syntax, Structure, and Semantics which details how to use it.

HTML5 Doctor also has a nice article on the figure and figcaption elements at http://html5doctor.com/the-figure-figcaption-elements/.
Share a link to this course
Please wait... Please wait...
Upgrade to get access to exercise files.

Exercise files video

How to use exercise files.

Learn by watching, listening, and doing, Exercise files are the same files the author uses in the course, so you can download them and follow along Premium memberships include access to all exercise files in the library.
Upgrade now


Exercise files

Exercise files video

How to use exercise files.

For additional information on downloading and using exercise files, watch our instructional video or read the instructions in the FAQ.

This course includes free exercise files, so you can practice while you watch the course. To access all the exercise files in our library, become a Premium Member.

Upgrade now

Are you sure you want to mark all the videos in this course as unwatched?

This will not affect your course history, your reports, or your certificates of completion for this course.


Mark all as unwatched Cancel

Congratulations

You have completed Dreamweaver CS5 Essential Training.

Return to your organization's learning portal to continue training, or close this page.


OK
Become a member to add this course to a playlist

Join today and get unlimited access to the entire library of video courses—and create as many playlists as you like.

Get started

Already a member?

Become a member to like this course.

Join today and get unlimited access to the entire library of video courses.

Get started

Already a member?

Exercise files

Learn by watching, listening, and doing! Exercise files are the same files the author uses in the course, so you can download them and follow along. Exercise files are available with all Premium memberships. Learn more

Get started

Already a Premium member?

Exercise files video

How to use exercise files.

Ask a question

Thanks for contacting us.
You’ll hear from our Customer Service team within 24 hours.

Please enter the text shown below:

The classic layout automatically defaults to the latest Flash Player.

To choose a different player, hold the cursor over your name at the top right of any lynda.com page and choose Site preferencesfrom the dropdown menu.

Continue to classic layout Stay on new layout
Welcome to the redesigned course page.

We’ve moved some things around, and now you can



Exercise files

Access exercise files from a button right under the course name.

Mark videos as unwatched

Remove icons showing you already watched videos if you want to start over.

Control your viewing experience

Make the video wide, narrow, full-screen, or pop the player out of the page into its own window.

Interactive transcripts

Click on text in the transcript to jump to that spot in the video. As the video plays, the relevant spot in the transcript will be highlighted.

Thanks for signing up.

We’ll send you a confirmation email shortly.


Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

Keep up with news, tips, and latest courses with emails from lynda.com.

Sign up and receive emails about lynda.com and our online training library:

Here’s our privacy policy with more details about how we handle your information.

   
submit Lightbox submit clicked