Is there an intent that takes pictures and doesn't save them automatically to the gallery? I'm currently using android.provider.MediaStore.ACTION_IMAGE_CAPTURE.
You can set the destination file uri with the following extra :
intent.putExtra(MediaStore.EXTRA_OUTPUT,<Uri>);
The file must be writable. once you finished with your file, simply delete it, and it won't appear in the gallery
if you want to keep the file on the sd, without having it visible in the gallery, you can simply change the extension of it, "file.tmp" will never show in the gallery.