How do I copy photos from an iPhone 4S to my PC?

Question

Platform:  iPhone 4S, IOS 6.0.1
I wish to transfer all photos stored on my iPhone to my PC.  Whether I use a Windows-based wizard, Adobe Photoshop, or Windows Explorer to read and copy files and folders, I can only access a small protion of the total library stored on my phone.  According to my iPhone's usage details, 4.7 GB of photos are resident on my phone; 225MB reside in Camera Roll; and 3 KB of data is allocated to Photo Stream (essentially, an empty store).
I've searched Apple's on-line support articles and forums, and the Web for advice.  Most of that advice seems to indicate photos must be placed in the Camera Roll album of my iPhone before they can be transferred to my PC.  This seems consistent with my finding that the DCIM folder on my iPhone (accessible in Explorer) contains files that correspond to the photos in my Camera Roll.
If photos must be present in the iPhone's Camera Roll before transfer to a PC, how do I place them there?  I've opened photos stored in my various photo albums and tapped the options button, but no option to send to Camera Roll is available.  Surely, there must be an unencumbered method that will allow me to retrieve my photos for cataloging and editing on my PC, beyond posting several hundred individual files to Facebook, or sending them via email.  Besides the obvious tedium of sending hundreds of files individually over the Internet, those methods compress the original file and decrease resolution.
Finally, before I upgrade the IOS, I want to be assured beyond any doubt that I have all of my full-resolution photos on an alternate, personal device for later unrestricted retrieval.  I routinely back-up my iPhone's contents, but even that back-up will at best simply "restore" the problem I already have to another i-device.  At worst - as is possible any time software or firmware is upgraded - data stored on the device could be corrupted beyond recovery.
What am I overlooking?
Thanks.

Answer 1

It is assumed that photos in places other than your camera roll originated on the computer and you have no need to transfer them back again since they are still there (or on a backup of the computer). They are of reduced quality anyway.
Note: The information below hasn't been updated since early 2013.
Some of the information below has subsequently appeared in a document by turingtest2: Recovering your iTunes library from your iPod or iOS device - https://discussions.apple.com/docs/DOC-3991
Your i-device was not designed for unique storage of your media. It is not a backup device and media transfer was planned with you maintaining a master copy of your media on a computer which is itself properly backed up against loss. Syncing is one way, computer to device, updating the device content to the content on the computer, not updating or restoring content on a computer. The exception is iTunes Store purchases which can be transferred to a computer.
iTunes Store: Transferring purchases from your iOS device or iPod to a computer - http://support.apple.com/kb/HT1848 - only purchases from iTunes Store
For transferring other items from an i-device to a computer you will have to use third party commercial software. Examples (check the web for others; this is not an exhaustive listing, nor do I have any idea if they are any good):
- Expod (free) - http://www.headlightsoft.com/expod/ - Mac, universal for 104.+ (newer machines try de-Tune)
- deTune (free) - http://www.headlightsoft.com/detune/ - Mac, 10.5+
- Senuti - http://www.fadingred.com/senuti/
- Phoneview - http://www.ecamm.com/mac/phoneview/
- MusicRescue - http://www.kennettnet.co.uk/products/musicrescue/
- Sharepod (free) - http://download.cnet.com/SharePod/3000-2141_4-10794489.html?tag=mncol;2 - Windows
- Snowfox/iMedia - http://www.mac-videoconverter.com/imedia-transfer-mac.html - Mac & PC
- iexplorer (free) - http://www.macroplant.com/iexplorer/ - Mac&PC
- Yamipod (free) - http://www.yamipod.com/main/modules/downloads/ - PC, Linux, Mac [Still updated for use on newer devices? No edits to site since 2010.]
- 2010 Post by Zevoneer: iPod media recovery options - https://discussions.apple.com/message/11624224 - this is an older post and many of the links are also for old posts, so bear this in mind when reading them.
Syncing to a "New" Computer or replacing a "crashed" Hard Drive - https://discussions.apple.com/docs/DOC-3141 - dates from 2008 and some outdated information now.
Copying Content from your iPod to your Computer - The Definitive Guide - http://www.ilounge.com/index.php/articles/comments/copying-music-from-ipod-to-co mputer/ - Information about use in disk mode pertains only to older model iPods.
Get Your Music Off of Your iPod - http://howto.wired.com/wiki/Get_Your_Music_Off_of_Your_iPod - I am not sure but this may only work with some models and not newer Touch, iPhone, or iPad.
Additional information here https://discussions.apple.com/message/18324797