Images in HTML

Adding an image

To add an image to a page, use the image tag

Image tags img do not have closing tags. The two main attributes you give to the img tag are src, the image source and alt, which is alternative text describing the image.

				
<img src="images/hello.png" alt="Hello World">
				
				

You can also get images from a web URL:

				
<img src="https://i.stack.imgur.com/ALgZi.jpg?s=48&g=1" alt="StackOverflow user Caleb Kleveter">
				
				

				
<img src="data:image/png;base64,iVBOR..." alt="Hello World">
				
				

Choosing alt text

Alt-text is used by screen readers for visually impaired users and by search engines. It's therefore important to write good alt-text for your images.

The text should look correct even if you replace the image with its alt attribute. For example:

				
<img src="https://www.thedeveloperbrains.com/img/logos/logo.png" alt="The Developer brains Logo">

				

Responsive image using the srcset attribute

Using srcset with sizes

				
<img sizes="(min-width: 1200px) 580px,(min-width: 640px) 48vw,98vw"
 srcset="img/hello-300.jpg 300w,
 img/hello-600.jpg 600w,
 img/hello-900.jpg 900w,
 img/hello-1200.jpg 1200w"
 src="img/hello-900.jpg" alt="hello">

				

sizes are like media queries, describing how much space the image takes of the viewport.

• if viewport is larger than 1200px, image is exactly 580px (for example our content is centered in container which is max 1200px wide. Image takes half of it minus margins)
• if viewport is between 640px and 1200px, image takes 48% of viewport (for example image scales with our page and takes half of viewport width minus margins).
• if viewport is any other size , in our case less than 640px, image takes 98% of viewport (for example image scales with our page and takes full width of viewport minus margins). Media condition must be omitted for last item.

srcset is just telling the browser what images we have available, and what are their sizes

• img/hello-300.jpg is 300px wide
• img/hello-600.jpg is 600px wide
• img/hello-900.jpg is 900px wide
• img/hello-1200.jpg is 1200px wide

src is always mandatory image source. In case of using with srcset, src will serve fallback image in case browser is not supporting srcset.

Using srcset without sizes

				
<img src="img/hello-300.jpg" alt="hello"
 srcset="img/hello-300.jpg 1x,
 img/hello-600.jpg 2x,
 img/hello-1200.jpg 3x">

				

srcset provides list of available images, with device-pixel ratio x descriptor.

• if device-pixel ratio is 1, use img/hello-300.jpg
• if device-pixel ratio is 2, use img/hello-600.jpg
• if device-pixel ratio is 3, use img/hello-1200.jpg

src is always mandatory image source. In case of using with srcset, src will serve fallback image in case browser is not supporting srcset.

Responsive image using picture element

				
<picture>
 <source media="(min-width: 600px)" srcset="large_image.jpg">
 <source media="(min-width: 450px)" srcset="small_image.jpg">
 <img src="default_image.jpg" style="width:auto;">
</picture>

				

Usage

To display different images under different screen width, you must include all images using the source tag in a picture tag as shown in the above example.

Result

• On screens with screen width >600px, it shows large_image.jpg
• On screens with screen width >450px, it shows small_image.jpg
• On screens with other screen width, it shows default_image.jpg