SEO: Using the same image on separate webpages with different 'alt' tags.

Question

If I use same image URL on separate webpages with different alt tags for each, will it have any negative impact on SEO?

What is the best practice to utilize the same image on separate webpages?

Answer 1

The alt attribute of the img tag is part of the content of the page, it should therefore be in the same context as the rest of the page (unless it is purely decorative in which case you probably shouldn't have any alt text, or use a background-image, etc.)

You could have the same image that is used on two different pages and the subject of those pages could be different. eg. a picture of a bike in a field of flowers could be used on a page about bikes and on another page about flowers. In this case the respective alt text could/should reflect more closely the content of the page and target the elements of the image that are relevant to the content. eg. "The Silvery Saracen Powertrax looks great in the mid morning sunshine." / "The field of yellow flowers turn in unison to gaze at the mid morning sunshine."

So, IMO it is perfectly acceptable to have different alt text on the same image in different contexts and the search engines should realise this. It would be wrong for search engines to apply any negative weight to this and having the correct alt text relating to the image and page content can only benefit IMO.

Answer 2

I believe it's recommended for SEO-purposes that if you use an image like:

http://www.abcphotos.com/babies/newborn.jpg

But also use the same image in a page that's located in another directory, like:

http://www.abcphotos.com/newborns/

Then you should copy the image into that directory (i.e., into /newborns) instead of using the same URL, like so:

http://www.abcphotos.com/newborns/newborn.jpg

The rationale is that you gain an internal link, and unique URL's that search engines and image sites can link back to. Additionally, you avoid any potential for duplicate content, especially if the two pages have similar content.

There are also reports that having directory names related to keywords can aid with indexing, which is not possible if images are in the same directory. For example, the URL:

http://www.abcphotos.com/toddlers/

This may help search engines to know that an image inside /toddlers is related to "toddlers". The same is true of file names - it's best to use names that reflect the keywords or content in which they can be found, which is not possible if you use the same URL.

So using the example above, after moving and renaming the "newborn.jpg" image, the URL might be something like:

http://www.abcphotos.com/newborns/newborn-boy.jpg

By the way, in addition to the alt attribute, you might also benefit from adding a title attribute, and image captions, or text above or below the image that relates to it contextually. Just be sure not to "overstuff" these with too many keywords.

See this for more:

Google Webmaster Tools: Image publishing guidelines

5 SEO techniques for website images

How to Get the Most SEO with Images

Lastly, remember to add each image URL to your sitemap so that search engines can index them.