Taking a photo of a visual work is making a reproduction of it—which means copyright alw gets involved—but that’s not all it is. Other laws might apply, too.
As a general rule, when you are lawfully in a public space, you have the right to photograph anything in plain sight, even if what you see is private property. If you’re on private property, such as a private museum or a gallery, then your right to photograph anything you see is subject to the property owner’s permission.
As for copyright, though, that comes into play with respect to the subject of your photography. Street art presents a case where a work might have copyright protections, but is also plainly visible from public spaces. Taking a picture of the work means you’ve created a reproduction, one of the acts covered by copyright law. If you take a photograph of just the artwork, and then attempt to sell prints of the photo, the artist has an excellent claim against you. But what if you use the photo for personal use only? Although it’s unlikely that there will be someone to stop you from taking the photograph, or using the photograph for personal use, like printing it and framing it for your wall, or using it as a desktop wallpaper on your computer, that’s still a technical violation of the law.
So why don’t you hear about street photographers getting sued for infringement when they take photographs? Sometimes it’s just a practical matter—the copyright holder might not notice the photo, wherever it’s used, or it might be close enough to a fair use that it’s not worth suing over. So although you probably won’t get in trouble for taking photos in Clarion Alley and then framing the photos for your personal home, you also don’t necessarily have a codified right to do so.
It’s also important not to confuse visual art, like street art, with other things that have limited copyright protection, such as building designs. Since 1990, certain architectural works have qualified for limited copyright protection – namely from construction of replica buildings. However, the law also grants a clear exemption for photography and other pictorial representations of buildings, stating that the copyright in protected buildings “does not include the right to prevent the making, distributing, or public display of pictures, paintings, photographs, or other pictorial representations of the work, if the building in which the work is embodied is located in or ordinarily visible from a public place.”