Altera UP2, VGA, load image problem

Hi,

I want to display my image using Altera up2. I wrote code (below). I converted png file to txt file, which contains bit representation of RGB.

When the image is small (128x128) it is ok but when the image is big( 640x480), the compilation doesn't end. Time compilation is growing and growin.

What can i do to load 640x480 image and display it?

Thanks

module vga(input clk, output hSync, output vSync, output r, output g, output b);
reg  CounterX;
reg  CounterY;
reg  Counter40;
reg        address;
reg        address2;
always @(posedge clk)
if(CounterX==800)    
   CounterX <= 0;
else    
   CounterX <= CounterX + 1;
always @(posedge clk)
if(CounterX==800)    
   CounterY <= CounterY + 1;
else if(CounterY==525)    
   CounterY <= 0;
always @(posedge clk)
if(CounterX < 640 & CounterY < 480 )
   begin    
   if(Counter40==40)       
      begin        
        Counter40 <= 0;        
        address2 <= 0;        
        address <= address + 1;         
      end    
   else        
      Counter40 <= Counter40 + 1;
   end
reg    vga_HS, vga_VS;
always @(posedge clk)
begin    
   vga_HS <= (CounterX>=656 & CounterX<752);     
   vga_VS <= (CounterY>=490 & CounterY<=492); 
end    
assign hSync = ~vga_HS;
assign vSync = ~vga_VS;
reg  data ;
initial $readmemb("test.txt", data);    
assign r = (CounterX < 640 & CounterY < 480 ) ? data : 0;    
assign g = (CounterX < 640 & CounterY < 480 ) ? data : 0;    
assign b = (CounterX < 640 & CounterY < 480 ) ? data : 0; 
endmodule