how to draw a image of size 600x400

[sar_van81]

hi,

can anyone say me how to draw an image of size 600x400. i tried as follows

QPainter p( this );
    uint x,y;
    x=550;
    y=500;
    QImage image(x,y,32 );
	 image.setAlphaBuffer( true );
	 for ( uint j =0; j <x; j++ )
	    {
 	     for ( uint i =0; i <y; i++ ) 
		{
    		   QRgb pixel;
    		   pixel = qRgb(0,0,255);
		   image.setPixel( i, j, pixel );
  		}
	    }
	p.drawImage(QPoint(0,0),image,0);

QPainter p( this );
    uint x,y;
    x=550;
    y=500;
    QImage image(x,y,32 );
	 image.setAlphaBuffer( true );
	 for ( uint j =0; j <x; j++ )
	    {
 	     for ( uint i =0; i <y; i++ ) 
		{
    		   QRgb pixel;
    		   pixel = qRgb(0,0,255);
		   image.setPixel( i, j, pixel );
  		}
	    }
	p.drawImage(QPoint(0,0),image,0);

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when i executed this it said the following error:
"
QImage::scanLine: Index 500 out of range
Segmentation fault ".

but i can succesfuly draw an image of size 500x500.
can anyone say me why is that so ..

thanks in advance,

saravanan