Identifying Year of a Photograph, with help from Google

Today, I was comparing notes with my brother, Walfrid, trying to guess when a photograph of our grandmother, Ida Maria (Hytönen) Huskonen was taken, probably by our father. I was able to enlarge the digital file of the photo large enough to be able to read the days of the month on a calendar hanging on the wall behind Grandma Huskonen. The month was January, and the first day of the month was on a Thursday.
Using Google, I found a website, Perpetual Calendar, at http://www.searchforancestors.com/utility/perpetualcalendar.html
With this tool, I was able to determine that in 1948, the first day of January was on a Thursday. After comparing notes, we agreed that this was the proper year.