HTML Images

HTML Images

Images can improve the design and the appearance of a web page.


Example

<img src=”pic_trulli.jpg” alt=”Italian Trulli”>

Example

<img src=”img_girl.jpg” alt=”Girl in a jacket”>

Example

<img src=”img_chania.jpg” alt=”Flowers in Chania”>


HTML Images Syntax

In HTML, images are defined with the <img> tag.

The <img> tag is empty, it contains attributes only, and does not have a closing tag.

The src attribute specifies the URL (web address) of the image:<img src=”url“>


The alt Attribute

The alt attribute provides an alternate text for an image, if the user for some reason cannot view it (because of slow connection, an error in the src attribute, or if the user uses a screen reader).

The value of the alt attribute should describe the image:

Example

<img src=”img_chania.jpg” alt=”Flowers in Chania”>

If a browser cannot find an image, it will display the value of the alt attribute:

Example

<img src=”wrongname.gif” alt=”Flowers in Chania”>

Note: The alt attribute is required. A web page will not validate correctly without it.


Image Size – Width and Height

You can use the style attribute to specify the width and height of an image.

Example

<img src=”img_girl.jpg” alt=”Girl in a jacket” style=”width:500px;height:600px;”>

Alternatively, you can use the width and height attributes:

Example

<img src=”img_girl.jpg” alt=”Girl in a jacket” width=”500″ height=”600″>

The width and height attributes always defines the width and height of the image in pixels.

Note: Always specify the width and height of an image. If width and height are not specified, the page might flicker while the image loads.


Width and Height, or Style?

The widthheight, and style attributes are valid in HTML.

However, we suggest using the style attribute. It prevents styles sheets from changing the size of images:

Example

<!DOCTYPE html>
<html>
<head>
<style>
img {
  width: 100%;
}
</style>
</head>
<body>

<img src=”html5.gif” alt=”HTML5 Icon” width=”128″ height=”128″>
<img src=”html5.gif” alt=”HTML5 Icon” style=”width:128px;height:128px;”>

</body>
</html>


Images in Another Folder

If not specified, the browser expects to find the image in the same folder as the web page.

However, it is common to store images in a sub-folder. You must then include the folder name in the src attribute:

Example

<img src=”/images/html5.gif” alt=”HTML5 Icon” style=”width:128px;height:128px;”>


Images on Another Server

Some web sites store their images on image servers.

Actually, you can access images from any web address in the world:

Example

<img src=”https://www.w3schools.com/images/w3schools_green.jpg” alt=”W3Schools.com”>


Animated Images

HTML allows animated GIFs:

Example

<img src=”programming.gif” alt=”Computer Man” style=”width:48px;height:48px;”>


Image as a Link

To use an image as a link, put the <img> tag inside the <a> tag:

Example

<a href=”default.asp”>
  <img src=”smiley.gif” alt=”HTML tutorial” style=”width:42px;height:42px;border:0;”>
</a>

Note: border:0; is added to prevent IE9 (and earlier) from displaying a border around the image (when the image is a link).


Image Floating

Use the CSS float property to let the image float to the right or to the left of a text:

Example

<p><img src=”smiley.gif” alt=”Smiley face” style=”float:right;width:42px;height:42px;”>
The image will float to the right of the text.</p>

<p><img src=”smiley.gif” alt=”Smiley face” style=”float:left;width:42px;height:42px;”>
The image will float to the left of the text.</p>

Tip: To learn more about CSS Float, read our CSS Float Tutorial.


HTML Screen Readers

A screen reader is a software program that reads the HTML code, converts the text, and allows the user to “listen” to the content. Screen readers are useful for people who are visually impaired or learning disabled.


Chapter Summary

  • Use the HTML <img> element to define an image
  • Use the HTML src attribute to define the URL of the image
  • Use the HTML alt attribute to define an alternate text for an image, if it cannot be displayed
  • Use the HTML width and height attributes to define the size of the image
  • Use the CSS width and height properties to define the size of the image (alternatively)
  • Use the CSS float property to let the image float
  • Use the HTML <map> element to define an image-map
  • Use the HTML <area> element to define the clickable areas in the image-map
  • Use the HTML <img>‘s element usemap attribute to point to an image-map
  • Use the HTML <picture> element to show different images for different devices

Note: Loading images takes time. Large images can slow down your page. Use images carefully.

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