topical media & game development
#javascript-processing-example-topic-image-edgedetection.htm / htm
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<script src="javascript-processing-example-processing.js"></script>
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</head><body><h1><a href="http://ejohn.org/blog/processingjs/">Processing.js</a></h1>
<h2>EdgeDetection</h2>
<p>Exposing areas of contrast within an image
by processing it through a high-pass filter.</p>
<p><a href="http://processing.org/learning/topics/edgedetection.html"><b>Original Processing.org Example:</b> EdgeDetection</a><br>
<script type="application/processing">
float[][] kernel = { { -1, -1, -1 },
{ -1, 9, -1 },
{ -1, -1, -1 } };
size(200, 200);
PImage img = loadImage("house.jpg"); // Load the original image
image(img, 0, 0); // Displays the image from point (0,0)
img.loadPixels();
// Create an opaque image of the same size as the original
PImage edgeImg = createImage(img.width, img.height, RGB);
// Loop through every pixel in the image.
for (int y = 1; y < img.height-1; y++) { // Skip top and bottom edges
for (int x = 1; x < img.width-1; x++) { // Skip left and right edges
float sum = 0; // Kernel sum for this pixel
for (int ky = -1; ky <= 1; ky++) {
for (int kx = -1; kx <= 1; kx++) {
// Calculate the adjacent pixel for this kernel point
int pos = (y + ky)*width + (x + kx);
// Image is grayscale, red/green/blue are identical
float val = red(img.pixels[pos]);
// Multiply adjacent pixels based on the kernel values
sum += kernel[ky+1][kx+1] * val;
}
}
// For this pixel in the new image, set the gray value
// based on the sum from the kernel
edgeImg.pixels[y*img.width + x] = color(sum);
}
}
// State that there are changes to edgeImg.pixels[]
edgeImg.updatePixels();
image(edgeImg, 100, 0); // Draw the new image
</script><canvas width="200" height="200"></canvas></p>
<div style="overflow: hidden; height: 0px; width: 0px;"><img src="javascript-processing-example-house.jpg" id="house.jpg"></div>
<pre><b>// All Examples Written by <a href="http://reas.com/">Casey Reas</a> and <a href="http://benfry.com/">Ben Fry</a>
// unless otherwise stated.</b>
float[][] kernel = { { -1, -1, -1 },
{ -1, 9, -1 },
{ -1, -1, -1 } };
size(200, 200);
PImage img = loadImage("house.jpg"); // Load the original image
image(img, 0, 0); // Displays the image from point (0,0)
img.loadPixels();
// Create an opaque image of the same size as the original
PImage edgeImg = createImage(img.width, img.height, RGB);
// Loop through every pixel in the image.
for (int y = 1; y < img.height-1; y++) { // Skip top and bottom edges
for (int x = 1; x < img.width-1; x++) { // Skip left and right edges
float sum = 0; // Kernel sum for this pixel
for (int ky = -1; ky <= 1; ky++) {
for (int kx = -1; kx <= 1; kx++) {
// Calculate the adjacent pixel for this kernel point
int pos = (y + ky)*width + (x + kx);
// Image is grayscale, red/green/blue are identical
float val = red(img.pixels[pos]);
// Multiply adjacent pixels based on the kernel values
sum += kernel[ky+1][kx+1] * val;
}
}
// For this pixel in the new image, set the gray value
// based on the sum from the kernel
edgeImg.pixels[y*img.width + x] = color(sum);
}
}
// State that there are changes to edgeImg.pixels[]
edgeImg.updatePixels();
image(edgeImg, 100, 0); // Draw the new image</pre>
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(C) Æliens
20/2/2008
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