Hi, I have a newbie question: I tried to make a simple slideshow with a transition effect.  I found that background() is fast, but image() and PImage.pixels[] are rather slow; I can't beat 30fps (max 24fps or so).  

Since I've seen numbers like 300fps on the Processing discussions, I suspect I'm doing something wrong.  Could someone give me a hint?  Here's my sample code, which is simple but can't go faster than 48fps with my PC (winxp, AthlonX2 5000+ 2.6GHz, 3GB RAM, GeForce6100):

//import processing.opengl.*;
PImage a, b;
PGraphics pg;
void setup()
{
 size(640, 480, P3D); // P2D similar; OPENGL slower
 a = loadImage("small.jpg");
 a.resize(width, height);
 b = loadImage("medium.jpg");
 b.resize(width, height);
 frameRate(120); // fps

 a.loadPixels();
 b.loadPixels();
 pg = createGraphics(width, height, P3D);
}

void draw()
{
 float ratio;
 ratio = frameCount / (60.0 * 10);
 ratio = constrain(ratio, 0.0, 1.0);
 transition(a, b, ratio);
 if (frameCount % 100 == 0) println(frameRate);
}

void transition(PImage a, PImage b, float ratio)
{
 int method = 0; // select 0, 1, 2, 3

 switch (method) {
 case 0: // 48fps
   background(a);
   tint(255, ratio * 255);
   image(b, 0, 0, width, height);
   noTint();
   break;
 case 1: // 40fps
   int x, y, loc;
   loadPixels();
   for (x = 0; x < width; x++)
     for (y = 0; y < height; y++) {
       loc = x + y * width;
       pixels[loc] = lerpColor(a.pixels[loc], b.pixels[loc], ratio);
     }
   updatePixels();
   break;
 case 2: // 44fps
   pg.beginDraw();
   pg.background(a);
   //pg.background(b);
   pg.tint(255, ratio * 255);
   pg.image(b, 0, 0, width, height);
   pg.noTint();
   pg.endDraw();
   background(pg);
   break;
 case 3: // 45fps
   background(a);
   blend(b, 0, 0, b.width, b.height, 0, 0, width, height, BLEND);
   break;
 }
}

Any suggestion will be appreciated.  Thanks.

Thanks for reply.  So I guess my fps is a normal, expected number, right?  

I'm not trying to do ultrafast framing, but when I try to do something a little bit more than simple stuff (e.g., with several img()'s or pixel tweakings in draw()), the fps easily drops down to 11-15.  

I probably need to go for non-realtime way, saving every frame and reconstruct them later on into 25fps video.  But this solution seems headache 'cause I like my video synchronized with music via minim.  

Or: I noticed background() is very fast, so what I need would be background() with tint (or alpha) facility.  I suspect the slowness of image() comes from rescaling, which I don't need in this specific case.  

Cheeeeeers