First it seems you might have a terminology problem.
I backed my computer through time capsule onto an external hard drive.
Is this hard drive plugged into the computer.. and you mean Time Machine.. the built in Mac backup software.
A time capsule is a piece of hardware that works as router and hard disk. You can indeed plug a hard disk (usb type) into the TC. And do backups to it.
When I go into the external to make sure it loaded my 19000 pictures, it says that they are stored in Time Capsule
Time Machine (TM) compacts all the files together. To access your photos you must first restore the entire library.
See Q15 here. http://pondini.org/TM/FAQ.html
does this mean they are not accessible through my external hard drive?
Yes, this is the case because they are not stored in a form that allows use until restored to the computer.
would I still be able to access Time Capsule to restore everything?
Yes, you can restore your computer from the TM backup.
However it is faster to use a different method called bootable clone which is the method Carbon Copy Cloner backup software uses to external drive plugged into your computer.. this means files are held in the exact same way they are on your local hard disk and in fact you can boot the backup drive instead of the internal drive. You can also access your iphoto library on the backup this way.. I highly recommend it .. although TM does a better job of incrementals and making a suitable method for migrating computers.