The solution I came up with is to use Springpad as a gateway to deep links into my Google Drive account. By putting items to be searched and scanned in common folders in Google Drive and linking to those folders using Springpad, it only takes a couple of steps to do an image search for content within Google Drive. Again, you're bouncing back and forth between two systems so it's not a perfect solution, but it does provide the opportunity to leverage some of the functionality.
There are some features that would be nice to have, such as the image thumbnails show up in Springpad from Google Drive. One bonus of use Google Drive for files rather than Springpad is that I can edit many of those files in Google Drive where I can't edit them in Springpad.
The balancing act between form and functionality, single solution and composite, perfect and good enough is a perpetual thing in the productivity space. Spend time finding what will work for you rather than finding what someone defined as the best answer for you and you will be far more successful in your endeavors.