weird resolution connecting to DVI port of monitor through DisplayPort-> DVI adapter

1

Dear Psychtoolbox users,

I have a weird resolution when I connect to a device (it is a spatial light modulator - SLM - , that can be controlled like a monitor through its DVI port) using a DisplayPort to DVI adapter (I think it is a DisplayPort - I spent half an hour trying to figure out whether it is a DisplayPort or an HDMI but I could not figure it out).


Screen('Resolutions',2) reports the correct resolutions (the highest for my device is 1280 x 1024). It is then possible to change it to allowed values, and the resolution displayed in the Intel Graphic control panel changes accordingly. Surprisingly, Screen('Resolution',2) reports a resolution of 1920 x 1536, exactly 1.5 times higher than the one I set and that I can see in the control panel. 

The PTB onscreen video then has a gray border. 


There is no problem if I use PTB with a different computer, where I can connect directly with the DVI (well, I know it indirectly, through a monitor which I connected both to the laptop and to the other computer: correct resolution with the other computer, 1.5 times wrong with the laptop; I did not yet try to connect the SLM to the other computer).


The easy solution is to send images of 1920 x 1536 pixels to the SLM. But I feel that I have more control on the instrument if I can set the computer to address the correct number of pixels.

Thanks in advance for any help.


Giovanni

 

2
(I post this as a new message because yahoo does not let me post an answer in the proper thread (message 20798)! Sorry, I do not know how to get around this problem, as the error message is just "could not send the message")

First of all thanks for the answer.
The laptop has Windows 10, the port is a displayport (I was able to figure it out).

Luckily timing is not important. I send one static image, that I can change at will; for the experiments I am doing, I can even wait a few seconds for images to switch and everything will work fine (again, the image is static). The suggestion to use Psychtoolbox for sending images to the SLM using Matlab comes from this web page: How to control a SLM with Matlab/Octave using Psychtoolbox

For the moment I will just change the number of pixels in the images I send (to the same number Screens('Resolution', 2) reports), I might be able to use Linux later.

Giovanni


3
(I was able to answer messages  by subscribing to the group)

By the way - I realized I did not answer the questionin your reply

The spatial light modulator (SLM) is an array of micron-sized liquid crystal cells, each of which can change the phase of the light that goes through it. The array then modifies the wavefront of a light beam in an arbitrary controllable way. Each cell (pixel) is controlled by a voltage, and the manifacturers organized the device by making it appear to a computer like a monitor; the image that you send corresponds to cell voltages.

By the way SLMs can be used to image the retina, as they help to correct the aberrations that result from imaging through the optics of the eye. And maybe for other psychophysics experiments too.