It depends on the resolution of the pictures......basically the better and more defined the picture quality, the higher the resolution. So for example, lets say each photo is 10MB. 1GB is 1024MB and 1TB is 1024GB. So, you could store close to 100 of your 10MB pics in 1GB of memory. Multiply that times 1000 and you have 100,000. There are some pre-loaded files on the drive that take up some space, so let's deduct 10,000 pictures. In this example, you would have the ability to store approx. 90,000 pictures at 10MB each.
Hope this helps.