John Mueller from Google talks about whether it's okay to publish diagrams as pictures or whether using HTML is more beneficial.
This issue was raised during a hangout by Google Webmaster Central on July 24th.
A website owner asked Müller how best to display charts with data on a website.
In Google's eyes, is it acceptable to publish the diagrams as pictures?
Or would it be an advantage to recreate the diagrams in HTML?
Here is what Müller advises.
John Mueller's answer
Mueller says there is nothing wrong with publishing a diagram as an image.
In fact, he recommends using images instead of creating diagrams with HTML code.
The transmission of images to images is a legitimate concern when it comes to crawling and understanding a page.
With the alt attribute, website owners can ensure that nothing is lost during translation.
“I think it depends a bit on what you want to achieve with the chart. Usually I would just add this kind of thing as an image and make sure you also have an understandable alt attribute for the image.
So if the diagram contains important information that you need to convey, add it to the alt attributes. So that we can record it as text, people who cannot see the image can also receive this information. But in general I would only use pictures. "
Another way to tell Google what the table is about is to add text content to the image.
Of course, Müller does not suggest to the website owner to publish an image on a website and leave it at that.
It is unlikely that a web page that contains only one image and no text in the body of the page will be well received in the search results.
Website owners also cannot rely on image search results, as Mueller says that diagrams in Google don't do pictures very well.
A website owner's best chances of posting a chart that appears in search results are:
- Publish the chart as an image with an understandable alt attribute.
- Add enough textual content to the image to explain what the table is about.
"I don’t think these types of charts usually do anything fantastic when searching for images because it’s difficult to imagine someone using Google Images to search for that particular diagram." But essentially, image is the best approach.
I don't think you would care much about converting this diagram to HTML and inserting the numbers and captions into text, as this could just as easily be pasted into the text of the blog post or into the alt attribute. "
Mueller hasn't added this part – but I don't want to mention the importance of page speed in a discussion about images.
When dealing with very large images, it is important that the file sizes do not get out of control.
Since page speed is a ranking factor, you should avoid publishing bloated pages with images of several megabytes in size.
The full question and answer can be found below (from (0:32)):