Fast way of getting pixels on screen in Java

Question

I'm working on a Java project that involves grabbing the colors of individual pixels on the screen at a fast rate. I initially used an AWT Robot for this task in the following code:

    Robot robot = new Robot();  
    int redVal = 0;
    
    for (int i = 0; i < 255; i++) 
        redVal += robot.getPixelColor(x[i], y[i]).getRed();

where x[],y[], represent the individual locations where I want to get the color value. On a relatively fast CPU, polling the 255 locations takes over 1.5 seconds, too slow for my application. Is there a faster way to get the color of specific pixels on the screen in Java, possibly through a screen capture then post-processing?

Do you pick the color from "random" locations on the "desktop" (so: other applications)? — GhostCat, Oct 29 '20 at 13:35
Does this answer your question? [Getting pixel information from the screen quickly](https://stackoverflow.com/questions/8350073/getting-pixel-information-from-the-screen-quickly) — Henry Le Berre, Oct 29 '20 at 17:22

score 1 · Accepted Answer · answered Oct 29 '20 at 14:12

You code will request individual pixels of the screen, which is considerably slow.

Instead, you can capture a screenshot (image) of the screen (or parts thereof), and then read the pixel values from that (in-memory) screenshot:

Robot robot = new Robot();
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
Rectangle area = new Rectangle(0, 0, screenSize.width, screenSize.height);
BufferedImage screenshot = robot.createScreenCapture(area);

int x = ...;
int y = ...;
Color pixelColor = new Color(screenshot.getRGB(x, y));

By the way, if you only need certain channels, you can extract them as follows:

int rgb = screenshot.getRGB(x, y);
int red = (rgb >> 16) & 0xFF;
int green = (rgb >> 8) & 0xFF;
int blue = rgb & 0xFF;

Fast way of getting pixels on screen in Java

1 Answers1