How can a developer protect themselves from publishing patented software? Is there any way of knowing if a certain type of program is patented?
If you've a seen similar thing pre-existing, chances are that it may be someone's intellectual property, and which then should be respected.
In this particular example, Wikipedia page on photographic mosaics [1] itself has a section on IP aspects of the same [2].
>> How can a developer protect themselves from publishing patented software?
The best approach is to respect the prior art and properly license the same as needed.
At times, a developer may have strong reasons to believe that the related prior patents are either not infringed or are invalid. In this case they should be ready to be challenged.
[1] https://en.wikipedia.org/wiki/Photographic_mosaic
[2] https://en.wikipedia.org/wiki/Photographic_mosaic#Trademark_...