Add random image test

misc/random_image.js

@@ -0,0 +1,35 @@
+/*
+ *  Output a 1024x1024 image generated using Math.random().
+ */
+
+function test(filename, threshold) {
+    var i, j, t;
+    var res = [];
+
+    res.push('P2\n1024 1024\n255\n');
+
+    for (i = 0; i < 1024; i++) {
+        for (j = 0; j < 1024; j++) {
+            t = Math.random();
+            if (typeof threshold === 'number') {
+                res.push(t >= threshold ? '255 ' : '0 ');
+            } else {
+                res.push(String(Math.floor(t * 256.0)) + ' ');
+            }
+        }
+        res.push('\n');
+    }
+
+    res = res.join('');
+    writeFile(filename, res);
+    print('Wrote', filename);
+}
+
+try {
+    test('rnd-threshold-01.pgm', 0.1);
+    test('rnd-threshold-05.pgm', 0.5);
+    test('rnd-threshold-09.pgm', 0.9);
+    test('rnd-threshold-none.pgm', null);
+} catch (e) {
+    print(e.stack || e);
+}