An Image Sprites is a single image which is merged with multiple images. The reason why Image Sprites are needed instead of inserting multiple images into a page is to SAVE network bandwidth as well as reduce the number of server requests. Since inserting many images into a page will take longer time to load the pages, merging images into a single will help reduce loading time. For these reasons, I would recommend to use “CSS Image Sprites” function instead of inserting multiple images. Unfortunately, most of designers/developers not support this function as default, but through this tutorial, you would be able to merge multiple images into a single image as well as manipulating CSS.

“Image Sprites” is strongly recommended for Web, because Web themes have many graphics as default. Therefore, reducing the number of images is necessary to let people as well as search engines visit your sites faster than before. Some times ago, I have already posted an example of a cartoon type animation with help of Image Sprites.

Let me give you an example for easier understandings. Here is lots of avatars I have to put into a page. Without Image Sprites, I have to insert 24 individual avatars into a page. It will generate 24 requests of your web server so that it will take a long time to load.

24 image files to load / 24 requests

Just 1 image file to load / 1 request

With using “Image Sprites”, Only one request and one loading time will be generated. Which one do you think better?

In addition, with the help of “Image Sprites”, you can make use of hover effect more easily. In this tutorial, I will describe how to use Image Sprites with hover effects (View Demo).

To get started (Preparation)

  1. You may need to prepare more than two same size images to be inserted into a page like the avatar image file above.
  2. For this tutorial, I will use these 6 images below as an example. All six buttons’ sizes are equal as 33×33.

3 left images will be used for normal links, and the rest of images will be used for hover effects.

This single image below will be used for “Image Sprites”.

Instruction

  1. Download .zip file or View Demo.
  2. Extract the compressed file onto your hard drive.
  3. Open “imagesprites.html” file using any TextEditor (Notepad/Dreamweaver).
  4. I will let you know some parts you need to replace so that you better modify some codes using text editor.
  5. This code is for this example so that your code will be different. You can refer to this code about how it works.
  6. Take a look at this part of the source code below:
.prev-button {
    width: 33px; height: 33px; border: 0px; background:url('/images/controllers.png') 0 0
}
a:hover .prev-button {
    width: 33px; height: 33px; border: 0px; background: url('/images/controllers.png') 0px -33px
}
.play-button  {
    width: 33px; height: 33px; border: 0px; background:url('/images/controllers.png') -33px 0
}
a:hover .play-button  {
    width: 33px; height: 33px; border: 0px; background: url('/images/controllers.png') -33px -33px
}
.next-button  {
    width: 33px; height: 33px; border: 0px; background:url('/images/controllers.png') -66px 0
}
a:hover .next-button  {
    width: 33px; height: 33px; border: 0px; background: url('/images/controllers.png') -66px -33px
}
image sprite
 As you can see, the first image’s position is “0 0” (.prev-button). The second image (.play-button) position is “-33px 0”. Because each width is set to 33px. Hence, the next image’s position should be “-66px 0”. On the other hand, for hover images, their Y position should be “-33px”, because each height is set to 33px.
  1. If you have set all, the next is to insert HTML codes for each image class like below:
<body style="background: transparent; margin: 0pt; ">
<div>
<a href="URL" target="_top"><img class="prev-button" src="/images/spacer.gif" /></a>
</div>

<div>
<a href="URL" target="_top"><img class="play-button" src="/images/spacer.gif" /></a>
</div>

<div>
<a href="URL" target="_top"><img class="next-button" src="/images/spacer.gif" /></a>
</div>
</body>
  1. If you don’t want an image to be linked, remove href= “URL” target= “_top” tag.
  2. Replace class names such as “prev-button”, “play-button”, and “next-button” to yours.
  3. Make sure the classes doesn’t have “.” at the very front.
  4. Modifying codes is done. You can apply this technique to other merged images.
  5. Make sure “spacer.gif” as well as your merged image file are also uploaded to the right place such as “/images/”.
  6. You are ready to check how “Image Sprites” works correctly. You will reduce the number of server requests as well as save network bandwidth with this CSS technique.

Posted by: Dhiraj kumar

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