Divided and duplicated frame capture output for ADNS 9800

I am trying to interface an ADNS 9800 mouse chip which I took from "Sharkoon SHARK ZONE M50" . The original PCB is still in place.

I am trying to obtain a framecapture, which should be 30 x 30 pixels. I have connected the ADNS 9800 with SPI to an Arduino UNO Rev 3 (i.e. 5V operating voltage). I.e. MISO, MOSI, SCLK, DGND, AGND, NCS. I did not connect any voltage, since I concluded from previous attempts that that did not yield a good frame capture.

The current problem is that I get a frame capture that is divided in 3 parts: square top left (with a good image of the surroundings), square bottom left (which is a duplicate of top left) and a rectangle on the right half of the screen of monotone grey colour (which does change depending on light conditions). See image. I want the full screen to be one image, not the divided mess it is now. Therefore, it may be a question of the resolution that is used, it may be that it is 15x15 instead of 30x30. However I do not know where this is determined/set.
Also, I find it strange that no input voltage seems to be needed to obtain an image from the camera.
See attachments for frame capture and code (arduino + processing).

ADNS_9800_BEP.ino (12.5 KB)

ADNS_9800_BEP_V2.pde (11.1 KB)