How many images should be optimised for 1 keyword?

[crocman]

Hello Moz,

I have a product category page and I have optimised 4 images around 1 keyword - is this bad practice? I worry Google will penalise me. Should I instead optimise them for other keywords?

Cheers

[EGOL]

There are two reasons to optimize an image...

1. you can use file name, alt attribute and captions to improve the SEO relevance of your page with the goal of ranking in the organic websearch results for a specific keyword.

2. you can use file name, alt attribute and captions to improve the SEO relevance of your image for ranking in the image search results.

How many images should you use?  Again, we have two goals... 1) ranking the page in the organic search results, and 2) ranking the image in the image search results.

For goal #1, I would not start manufacturing images just to increase the number of them that you have on your page.  Just as I would not publish a ton of yada yada yada text just to pad the word count. However, if you have a lot of good relevant images that people will actually appreciate, then you should use as many as you think will be useful for your visitors or as many as is needed to properly illustrate your articles.

For goal #2, there are two things to consider.   First, image name, alt, and caption will qualify you for image search but they are of minor importance for ranking you.  The amount of searcher engagement is what will rank you.  So, tossing up a bunch of crappy images isn't going to do any more for you than publishing yada yada yada text on your page.  You need images that people will engage.  How many?  I would publish as many as you can economically produce and that can be justified with what you can do with the traffic that they will pull.  If you have two highly competitive images google will rank both of them.  If you have five, six, seven highly compeitive images, google will rank all of them.  If you are not capable of producing highly competitive images then don't bother producing any more than you need to illustrate your article.  They have the same value as yada yada yada text.  But, you can publish images optimized for the same keyword on different pages of your website and all of them have the potential for ranking for their optimized keyword in image search - if they are competitive enough in terms of searcher engagement.

I firmly believe that if your images perform well in image search that will help your page rank better in web search.  Google knows that people who have access to good images often are the same people who have the experience and knowledge to rank well in websearch.  That is a personal belief.  Some might argue, but I am convinced.

[Joe.Robison]

Never heard of a penalization around over-optimizing images, I think that's a very small concern.

Like EGOL said, optimizing the file name with keywords and dashes is actually one of the best ways to go. Google's image search engine is very rudimentary so it uses the filename as a large % of the image ranking algorithm. Would take the approach of describing the image succinctly in the alt text while including and image.

As far as helping the page rank in the normal SERP results, images have a very small contribution. So it's a best practice but don't waste too much time on it unless it's a massive site where you can apply scalable changes all at once.

[EGOL]

I would use image names, alt attributes, and captions that fit the images as closely as possible.