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43 lines
1.2 KiB
Plaintext
43 lines
1.2 KiB
Plaintext
/**
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* Histogram.
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*
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* Calculates the histogram of an image.
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* A histogram is the frequency distribution
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* of the gray levels with the number of pure black values
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* displayed on the left and number of pure white values on the right.
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*
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* Updated 28 February, 2010.
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* Note that this sketch will behave differently on Android,
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* since most images will no longer be full 24-bit color.
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*/
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size(200, 200);
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// Load an image from the data directory
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// Load a different image by modifying the comments
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PImage img = loadImage("cdi01_g.jpg");
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image(img, 0, 0);
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int[] hist = new int[256];
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// Calculate the histogram
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for (int i = 0; i < img.width; i++) {
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for (int j = 0; j < img.height; j++) {
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int bright = int(brightness(get(i, j)));
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hist[bright]++;
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}
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}
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// Find the largest value in the histogram
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int histMax = max(hist);
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stroke(255);
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// Draw half of the histogram (skip every second value)
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for (int i = 0; i < img.width; i += 2) {
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// Map i (from 0..img.width-1) to a location in the histogram (0..255)
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int which = int(map(i, 0, img.width, 0, 255));
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// Convert the histogram value to a location between
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// the bottom and the top of the picture
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int y = int(map(hist[which], 0, histMax, img.height, 0));
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line(i, img.height, i, y);
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}
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