DE2_TV searching XY coordinates of pixels

Altera_Forum · ‎07-24-2009

Hi @all,

I am currently working with the DE2 Dev.&Edu. Board with Cyclone II.

In my project I am supposed to do a simple blob detection. The blobs are represented by white dots on black background.

Since I am new I decided to start with the DE2_TV example to become familiar with the dataflow. If I did understand it correct the program does the manipulation of the data pixel-wise, which means that the information which pixel it is actually manipulating should be available.

But I am a little bit confused which register does hold the information.

I thought it should be the ports oCurrent_X and oCurrent_Y from the VGA_Ctrl module, but if thats the case why is the register 11 bit.

This would allow a resolution of 2048x2048 (I know this is not the correct relation, it's just a example).

But the output of the VGA has only a resolution of 640 x 480, so the coordinates of X and Y should be lay inbetween.

Can someone help me here?

Where can I get the X and Y coordinates for the pixels?

regards,

Alex

Altera_Forum · ‎07-24-2009

Yes, you are right. (oCurrent_X, oCurrent_Y) means coordinates for the pixels while (oVGA_BLANK==1). Never mind bit length.

Altera_Forum · ‎09-05-2009

Do the coordinates change on every clock tick?

How can I make sure that I don't proceed a pixel twice or miss a pixel?

module run_line_detection(CLK_27, CLK_50, iReset, iVGA_R, iVGA_B, iVGA_G, iPosX, iPosY, iThresh, 
        iVGA_BLANK, iDIG, oVGA_R, oVGA_B, oVGA_G, oTXD_DATA, oTXD_Start, ProceedingA_Run, previousPosX);
// INPUT
input            iThresh;
input            iVGA_R;
input            iVGA_B;
input            iVGA_G;
input            iPosX;
input            iPosY;
input         CLK_27, iReset, CLK_50;
input          iDIG;
input                iVGA_BLANK;
// OUTPUT
output reg        oVGA_R;
output reg        oVGA_B;
output reg        oVGA_G;
output reg      oTXD_DATA;
output reg            oTXD_Start;
// INTERNAL
parameter TRUE = 1'b1;
parameter FALSE = 1'b0;
output reg ProceedingA_Run;  //flag to determine if pixel belongs to a run
output reg  previousPosX;  
reg  previousPosY;  
reg  pixelPosX;  //store start position of run on X-Axis
reg  pixelPosY;  //store start position of run on Y-Axis
reg   pixelRunLength; //count number of pixels belonging to run
reg  runRegister;//storage for detected runs
reg        foundRun;  //global counter for detected runs
reg  writeBank; //flag to switch between write commands
reg  frameCounter; //counter for frames 1-3 to change pointer on run-register in SRAM
reg  counter;
always@(posedge CLK_27)
begin
    if(!iReset)
    begin
        previousPosX = -1'd1;
        previousPosY = -1'd1;
        ProceedingA_Run = FALSE;
        counter = 0;
    end
        
    if ( (iPosX <= 640) && (iPosY <= 480) )
    begin
            //value > Threshold => pixel belongs to blob
            if((iVGA_R > iThresh) && (iVGA_G > iThresh) && (iVGA_B > iThresh) )
            begin
                oVGA_R = iVGA_R;
                oVGA_G = iVGA_G;
                oVGA_B = iVGA_B;
                
                if(iVGA_BLANK)
                begin
                    if(iPosX == (previousPosX +1))
                    begin
                
                        //Pixel is start point of a new run
                        if( ProceedingA_Run == FALSE )
                        begin
                            ProceedingA_Run = TRUE;
                            pixelPosX = iPosX;
                            pixelPosY = iPosY;
                            pixelRunLength = 0;
                        end
                        //increase number of counted pixels for current run
                        pixelRunLength = pixelRunLength + 1; 
                    end
                    else
                    begin
                        //Actually proceeding a run, but current pixel does not belong to it the end of the run is reached
                        if( ProceedingA_Run == TRUE )
                        begin
                            ProceedingA_Run = FALSE;
                            //store run only if longer than 1 pixel
                            if( pixelRunLength > 1 )
                            begin
                                runRegister <= {pixelPosX, pixelPosY, pixelRunLength};
                                foundRun = TRUE;
                            end
                            else
                            begin
                                foundRun = FALSE;
                            end
                        end        
                    end
                end //end VGA_BLANK                
            end
            else
            begin    
                if(iVGA_BLANK)
                begin                        
                //Actually proceeding a run, but current pixel does not belong to it the end of the run is reached
                    if( ProceedingA_Run == TRUE )
                    begin
                        ProceedingA_Run = FALSE;
                        //store run only if longer than 1 pixel
                        if( pixelRunLength > 1 )
                        begin
                            runRegister <= {pixelPosX, pixelPosY, pixelRunLength};
                            foundRun = TRUE;
                        end
                        else
                        begin
                            foundRun = FALSE;
                        end
                    end
                end //end VGA_BLANK        
                oVGA_R = 10'b0000000000;oVGA_G = 10'b0000000000;oVGA_B = 10'b0000000000;        
            end // threshold
    end //if ( iPosX <= 640 && iPosY <= 480 )
    else
    begin
        foundRun = FALSE;
    end
    
    if(foundRun == TRUE)
    begin
        foundRun = FALSE;
        runRegister <= {8'd200, 8'd170, 8'd15};
    end
        
    previousPosX = iPosX;
    previousPosY = iPosY;
    
            
    //change register for runs if end of frame reached
    if( (iPosX == 640) && (iPosY == 480 ))
    begin
        previousPosX = -1;
        previousPosY = -1;
        ProceedingA_Run = FALSE;
        
    end    
    
    
    if(foundRun) begin
        tmpRun = runRegister;
        TXD_Buffer = {TXD_Buffer, tmpRun, 2'h0A};
        TXD_Buffer_Flag = {TXD_Buffer_Flag, 5'b11111};
    end
    
    if(TXD_Buffer_Flag) begin
        oTXD_Start = 1'b1;
        oTXD_DATA = TXD_Buffer;
    end
    else
    begin
        oTXD_Start = 1'b0;
    end
    
    TXD_Buffer_Flag = {TXD_Buffer_Flag, 1'b0};
    TXD_Buffer = {TXD_Buffer,8'b00000000};
end
endmodule

I have tested this code now with an wave input file. But every time when the procedure detects a pixel as above the threshold, the control variable proceedinga_run becomes undefined or represents 0 and 1 at the same time.

Isn't possible to use register values in following iterations?

Do they get lost?

If I check for the previous position previousposx it works very well.

Should I start from scratch or even change to SystemC ?

I've invested now more than 2 months of work and don't make real efforts. Maybe doing it in Verilog was a bad decision?!

thanks for your support

Altera_Forum · ‎09-18-2009

Ok, for now I have skipped the method of Run-Length-Encoding based Blob detection and have reduced the algorithm to just compute a bounding box around the blob.

For simplification I just compute the bounding box around the blob for a image data that contains only a single blob.

I still use the analog video in and it works!

At the beginning I set min- and maxX -Y values and change them, dependend on the position of the pixel that I just proceed. I keep changing the values until the iPosX and iPosY values become (0,0) again, which means that a new frame has just started.

The computed center point of the blob is displayed on the HEX-display and doesn't show any flickering.

I will offer the source some time in the future, but I have to clean it up a little bit.

So the next steps will be the extension of the blob detection to track multiple blobs in the same frame and then use some other interfaces of the DE2 board to provide 3 video inputs at the same time.

I will keep updating this thread to provide my proceedings.

cu

Alex

Altera_Forum · ‎01-13-2010

I am just getting started with the DE2 board. I too am looking at the DE2_TV example and need to manipulate pixel information.

Could I receive the code where you are able to do this? Ultimately all I am looking to do is flip the image. I think your code can help me to start understanding how to do this.

Thanks

-M

Altera_Forum · ‎01-15-2010

Hi,

sry for the late reply. I am busy working on a project.

I have attached for you the whole project folder, which is basically the manipulated version of the DE2 demonstration.

The interesting module for you should be run_line_detection.sv

There I do a pixel-wise detection of binary large objects in a frame.

The beginning of a frame is identified by the pixel coordinates.

I think if you just delete most of the source an do the flipping of the pixel-values, then you are done.

The source is very bad because I am still working on it.

Just ask if something is unclear.

regards,

Alex

Altera_Forum · ‎07-05-2010

Hi Spellic

I am also using the same DE2_TV module for detecting any thing which came in the range of camera in the fixed background. Actually my project is to detect Face in the real time but for my convince i am supposing that what ever comes in camera range will be the face. Now i am confused in selecting the background. Please help me and also give me suggestion in getting started as i am new to this module and not have enough info. If you have some material please share me or if i can use your code then tell me how to use.

Thanks

Altera_Forum · ‎07-22-2010

Hi raosaifullah,

sorry for the late reply, I don't check the forum at regular intervals.

Did you have a look at the source code I posted the last time?

Is your camera connected to the analog interface?

The problem with doing foreground-background segmentation is to know the background. The simplest way would be to use a black background (if your skin color is not black). This way you could just identify all relevant pixels by their color value.

This is of course not very reliable, since you will loose some information that you want to have, like your eyes. But it's a start.

Do you display the output on the VGA monitor?

If yes you could extend the identification of the pixels by their color values, with changing the color of the relevant pixels to green for example. This way you could see how the approach works.

good luck.

Spellic

Altera_Forum · ‎07-22-2010

Thanks for your reply.

I have already done this what you have answered. i can detect any color by its pixel information. and now fixing black back ground. Now i need help in drawing rectangle around the detected face. Please help me in this. Also i want to save the pixel of detected face in SRAM of DE2 board at real time. Can you help me in this?

Thanks

Regards

Rao Saifullah

Altera_Forum · ‎08-17-2010

That might be kind of tricky.

To identiy the edge coordinates for the rectangle, process the image data and just keep the minimum and maximum coordinate values of the detected face.

This allows you to create a bounding box around it.

To draw the bounding box you need to store the image data in a frame buffer, when you search for the min-/max-values. Then you can use the bounding box data to just draw all pixels on the border of this bounding box in one color. (e.g. white)

Hope that helps.

Alex

Altera_Forum · ‎12-08-2010

I am just the beginner of the verilog code. After i get the min-/max-value, how can i draw the bounding box? Can anyone share the code?

Altera_Forum · ‎12-22-2010

hello guys,

i just work on my final year project for my degree.but my knowledge is less about coding / c / c + + / vhdl..can anybody xplain more about the number in [ ] the right below.

for ur information, this some codes is Taken from the tutorial in TRDB_LTM_UserGuide_v1.23.

input iTOUCH_IRQ;

input [11:0] iX_COORD; // X coordinate form touch panel

input [11:0] iY_COORD; // Y coordinate form touch panel

input iNEW_COORD; // new coordinates indicate

output [2:0] oDISPLAY_MODE; // displaed photo number

tq.

Altera_Forum · ‎01-04-2011

How to display the bouding box after computing the coordinate?