Can I scan a bar code through glass, plastic or other surfaces? How about off a computer screen??
Scanners can scan through some reflective surfaces. CD cases, plastic shrink wrap, or plastic bags are examples of materials that can be scanned through. Windshields and other glass surfaces are difficult to scan through for traditional barcode scanners.
One major advantage of using a smartphone to scan barcodes is that instead of using a laser or ccd scanner it uses its built in camera to take a picture of the barcode and decipher the code. This allows it to easily decipher codes displayed behind all kinds of surfaces – to go places no laser has gone before! The disadvantage is that they are not completely impervious to reflection, and can actually be quite heavily affected by the kind of reflection that makes taking a crisp photograph difficult. Like in the image below…a barcode positioned in that reflective glare would not scan. Lesson: leave the shininess for the diamond you are going to buy her.
In general…if you can avoid having to scan through a surface, do that. Generally this will make your life easier. Generally speaking.