We have already reviewed an app to resize pictures on Android even in batch. But Nexus 7 2013 running Kitkat has a default feature to change the quality and the size of pictures right from the Gallery application.
Resize pictures on Nexus 7 2013 by doing as follows:
1. Open Gallery application
2. Open the Photo you want to resize
3. Tap the 3dot icon on the top right and then tap Edit.
4. Tap the 3dot icon again and tap Export.
5. Now the Export Flattened Image menu is opened and you can change the size or change the quality of the selected image
6. Tap Done and your image with the new size/quality is saved on the same directory as the original image exists