Many a posting on this subject atests to the frustration and bewilderment of Shopify's inabiliity to produce a direct URL for an image-sitemap.xml to be recognized by Google et al, even though Shopify is able to do as much with the auto produced sitemap.xml file or even a verify(email).html file.
I have just put a bunch of effort into SEO'ing my image names only to discover the above brick wall when wanting to submit an image-sitemap.xml to Google et al. A lot has been written about this, so I shall refrain from engaging in repitition.
My call out is to the community seeing that Shopify apparently is mute on the subject.
If ALT text is at least as close to or as good as image file names, why is Shopify's inabiliy to create a URL direct to an image-sitemap.xml file an issue at all? Their own ALT text program ( https://apps.shopify.com/alt-text ) is a top seller along with SEO Image Optimizer ( https://apps.shopify.com/seo-image-optimizer ).
Have I been sold a gift SEO horse by putting lots of effort into SEO'ing image file names only to discover ALT text is just as good? (All my ALT text fields were SEO'd anyway, but, yes, I am upset at the lost effort put into SEO'ing the image file names).
Some folks have even mentioned changing plalforms over this.
So two querries / observations for comment:
1) Is ALT text just as good or nearly as good as image file name text? If not, why not? If mostly yes, then is there really an issue with image-sitemap.xmls not being supported by Shopify?
If the asnwer is "ALT is as good or nearly as good as image file names," then . . .
2) Is the primary advantage of utilizing image file names via an image-sitemap.xml file one of being able to have more keywords being indexed on a site?
Cheers - James
I think we have to divide this up into what each thing does.
No one knows exactly how influential each component is. It's all just ediucated guesses and flawed tests.
The alt attribute (alt text)
This is designed to help people/bots who can't see the image understand it. It is known that Google takes this text into account for image searches, and it may have a minor influence for normal search as well.
Not to be mixed up with the title attribute or the ficticious alt tag.
Text in the URL is known to have a minor influence on the resource it represents. This is probably more siginficant for resources like images, where there is little other information to go on.
This is a mechanism to inform search engines which URLs are your preferred URLs. And in return they will tell you a bit about how well they are indexed.
They do not affect ranking, but provide hints on where you want the search engines to crawl.
If they spot duplicate content, a sitemap can be used as a tie breaker to decide which version becomes the canonical one.
So a sitemap in itself does not add textual information to an image. Or affect what it ranks for. All it can do is push search engines to index a specific URL for an image.
Search engines primarily find URLs via links. The image URL that is most likely going to be indexed is the one used on the pages.
If the sitemap does not list the same URLs, you may see a poor indexing rate for that sitemap.
This can get tricky with images, as there are often multiple URLs for the one image, in different sizes etc. Or versions on a CDN as well as ones on the local server.
This may be where the sitemap can help, by hinting at the version you want indexed. Which should be the primary image at full size. And the one with nice text in the URL :-)
It is also beleived that search engines go beyond just the alt text and URL to determine the subject of an image. Captions, near by text, and even the subject of a page containing an image may be factors.
Google now has tecknology to look into an image and work out what it is about. At some point that will roll into their search engine.
All the above are factors that can influence image ranking. It's not a case of doing one or the other, but getting as much of it right as possible.