For online publishers, Google AdSense is nothing short of a goldmine. When generating ads for a certain page, AdSense relies on an analysis of the cached version of that page to generate contextual ads. Being closely related to the content of the page, and therefore to what the visitors are looking for, such ads are more interesting and have higher CTRs (click-through rates).
Most ads these days seem to be placed on pages that are made up primarily of text-based content. However, with the advent of digital photography, many people publish their travel photographs online. Such photo albums are mostly automatically generated and are oftentimes made up of individual HTML pages that contain little else beyond a photograph and the obligatory navigation links.
The question is, would it be possible to earn advertising income from such pages?
A lot of the skepticism I've seen in advertising forums seems to be derived from the fact that Google's AdSense Program Policies explicitly forbid placing ads on non-content-based pages. An almost empty page, made up of a single photograph with no associated metadata, would most certainly qualify as non-content-based. Technically there would be little for AdSense to work with when trying to generate contextual ads for it. However, a photograph is content, and attaching the proper metadata to its enclosing HTML page and perhaps including a small description, is enough for AdSense to be able to generate contextual ads when such ads are available. Click on the cruise ship photograph to the right of this paragraph for an example.
Another piece of criticism to the idea of running ads on photo albums seems to come from people whose experience led them to believe that oftentimes AdSense generates no ads for such pages. This, of course, has to do with the subject of the photograph, as determined from the associated metadata. Unlike a properly named photograph of an exotic place, one whose name is simply the name of a person will most likely not trigger any contextual ads. However, if included with each photograph is the name of the place where the photograph was taken and a short description of the equipment used in taking it (camera, lens type, film, etc.), AdSense may generate location or photography-related ads instead. Such a practice may be construed as deceptive - for example a head shot with a blurred background bringing in Hawaii-related ads just because it is annotated as having been taken there. Publishers may be better off replacing ads on such pages with links to other pages on their site, even if only to stay on the good side of Google. In any case, one thing to keep in mind whenever making decisions about what to do with such photographs is that AdSense employs geo-targeting, and so the ads that publishers see may be different from those seen by their site's visitors.
Back to the potential for lack of ads on certain travel album pages, publishers should not expect earnings from every photograph. Throughout my experiments with placing one, two and three ad units on the pages of my travel albums, I have seen empty ad units a number of times, and whether for a certain album this will be the exception or the norm can only be subject for speculation. An album that is made up of repetitive, obsessive-compulsive shots of one's wife or children, no matter how sweet and gorgeous the author may think they are, is not likely to generate much revenue (I never ran across an ad for a mental institution, I wonder how such a thing would look like).
Finally, some people object to the idea of placing ads on personal pages simply because they believe such ads would scare their visitors away. This is a common misconception that stems from the early days of online advertising when ads consisted mostly of annoying, in your face, flashy pop-ups. Not only are most modern browsers, such as Firefox, fighting that, but these advertising methods are explicitly prohibited by Google's AdSense Program Policies. Many publishers claim to see better CTRs for ads that blend in with the rest of the page, convincing visitors that they are really part of the content - highly contextual ads may complement that content (the photograph in our case) and benefit the site's visitors.