Oh sorry--I misunderstood. It sounds like you have images used by apps that are showing up in your gallery, which you don't want, right? I initially thought you didn't want photos you took to auto-upload to your Google+/Picasa albums, based on the title of your post.
To prevent unwanted images from showing up in your Gallery, you need to locate the folder that contains those images (using any file explorer app) and create a blank text file titled ".nomedia" (the leading period is important). This will make the system ignore that folder when searching for media.