I've written some image analysis software that can determine the basic shape, color, and dimensions (in cm) of what it considers to be the most dominant object in the image.

I've also created a database of objects for the algorithm to choose from:

Code:
Item | Shape | Colors | Width range | Height range

Box | rectangle | brown, black, white | 20-50 cm | 10-30 cm
Basketball | circle | orange | 20-25cm | 20-25 cm
Backpack | rectangle | black | 40-50 cm | 20-30 cm
.
.
.
 etc.
An example would be where the system detects a black rectangle that is 42cm wide and 26cm in height. In this case, both 'box' and 'backpack' would qualify as correct answers. Are there any good ways to make an educated guess as to which of the two items it could be, such as 75% chance it's a backpack, 25% chance it's a box (possibly based on the fact that boxes have a chance of being 3 different colors and a wider range of sizes, as opposed to the backpack which could only be black)?

Other advice is also welcome. I'm having to teach myself about image recognition, so if there are other things I should be trying to pull out of an image, or a different way that I should be going about the database, those comments would also be greatly appreciated!