The ImageExplorer jailbreak application, developed by Erik Eisenberg, helps you find and use images on your iPhone, iPod Touch or iPad. This application is similar to AudioExplorer+ and VideoExplorer, it searches the contents of other applications on your iOS device for images files (even images without file extensions) and lists them in an easy-to-view format.
Once the images are found, you can simply add the images to your Camera Roll, open them in other applications, send via email (multiple files will be sent as zip archives) or even set as a wallpaper, without using the Camera Roll (only available on iOS 7).
Images can be found either in the application tab (which lists the files by app) or in the files tab (which filters out empty folders and non-image files to make it easier to find what you are looking for). You can tap once to see a preview of an image, from which you can also view all image files for that application or in that directly at once. You can tap twice to use the image as a wallpaper or a lock screen background. Tap the button on the right hand side to open the image in another application, or add it to your Camera Roll. You can also add several images at once to your Camera Roll, either tap and hold to switch between single and multiple selection modes, or use the action button on the upper right hand corner.
ImageExplorer is a commercial package ($1.99) on the Cydia Store in the default BigBoss repo. If you end up trying this application let us know what you think of it in the comments.