Re: [Java-player-users] Missing data in images?

[Radu B. R. <ru...@cs...>]

Hi Fred,

Going to do some tests with some live cameras this week and fix this. I 
also noticed that by encoding the color in Java byte format (signed, 
-127..128), the colors could get messed up, as normally they should be 
unsigned (0..255). I will try to change everything to integer and then 
test. If that works ok, I'll patch the library and let you know.

Best,
Radu.

Fred Labrosse wrote:

>Hello,
>
>Finally found some time...
>
>On Thursday 16 Mar 2006 10:24, Radu Bogdan Rusu wrote:
>  
>
>>Hey Fred,
>>
>>If nobody else figures it out, I will try to do something about it on
>>the plane. In general though, it is better to:
>>- first, test if the data is ready, using the
>><CameraInterface>.isDataReady () method
>>- then try to actually read the data from CameraInterface's buffer.
>>
>>Example:
>>PlayerCameraData camdata = new PlayerCameraData ();
>>
>>if (camdata.isDataReady ())
>>camdata = cam.getData ();
>>    
>>
>
>I've done:
>
>                System.out.println("Waiting for image to be ready");
>                while (!cam.isDataReady())
>                    {
>                        // Do nothing, just wait for the data to be ready.
>                    }
>                System.out.println("Getting image");
>                camdata = cam.getData();
>
>and that indeed (almost) solves the problem I was reporting.  Only almost 
>because to save the image I have to do:
>
>        for (int h = 0; h < height ; h++)
>            for (int w = 0; w < width; w++)
>                {
>                    file.write(data[(w * 3) + (h * width * 3) + 1]);  // Red
>                    file.write(data[(w * 3) + (h * width * 3) + 2]);  // Green
>                    file.write(data[(w * 3) + (h * width * 3) + 0]);  // Blue
>                }
>
>in order to get the colours right.  The interesting bit is that v4l normally 
>creates BGR pixels (i.e. blue and red swapped).  However, I seem to be 
>getting BRG pixels from the CameraInterface.  But that's easy enough to fix.
>
>Finally, is the isDataReady()/getData() pair is in a loop, it hangs on the 
>second isDataReady() (or am I not supposed to be using it as I do?  Also, at 
>the same time I do get loads of
>
>warning : tried to push onto a full message queue
>error   : tried to push 2/1 from/onto 4/0
>
>while trying to get the second image.  This is with version 2.0.1 of 
>javaclient and a fairly recent cvs version of player.
>
>Cheers,
>
>Fred
>
>
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-- 
| Radu Bogdan Rusu | http://rbrusu.com/
| http://www9.cs.tum.edu/people/rusu/
| Intelligent Autonomous Systems
| Technische Universitaet Muenchen