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<!DOCTYPE html> <html> <body> <h1>HTML5 Canvas</h1> <h2>The getImageData() Method</h2> <canvas id="myCanvas" width="300" height="150" style="border:1px solid grey"></canvas> <script> const c = document.getElementById("myCanvas"); const ctx = c.getContext("2d"); ctx.fillStyle = "red"; ctx.fillRect(10, 10, 50, 50); var imgData = ctx.getImageData(30, 30, 50, 50); red = imgData.data[0]; green = imgData.data[1]; blue = imgData.data[2]; alpha = imgData.data[3]; alert(red + " " + green + " " + blue + " " + alpha); </script> </body> </html>
