Move files to public folder

public/fbp.js

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+// Helper: Next power of 2
+function nextPow2(n) {
+  return 1 << (32 - Math.clz32(n - 1));
+}
+
+// Basic Cooley-Tukey FFT (real/imag arrays)
+function fft1D(re, im) {
+  const N = re.length;
+  if (N <= 1) return;
+
+  // Bit-reversal permutation
+  const rev = new Uint32Array(N);
+  let logN = Math.log2(N);
+  for (let i = 0; i < N; i++) {
+    let x = i,
+      y = 0;
+    for (let j = 0; j < logN; j++) {
+      y <<= 1;
+      y |= x & 1;
+      x >>= 1;
+    }
+    rev[i] = y;
+  }
+  for (let i = 0; i < N; i++) {
+    if (i < rev[i]) {
+      [re[i], re[rev[i]]] = [re[rev[i]], re[i]];
+      [im[i], im[rev[i]]] = [im[rev[i]], im[i]];
+    }
+  }
+
+  // FFT
+  for (let s = 1; s <= logN; s++) {
+    const m = 1 << s;
+    const m2 = m >> 1;
+    const wAngle = (-2 * Math.PI) / m;
+    const cosW = Math.cos(wAngle);
+    const sinW = Math.sin(wAngle);
+    for (let k = 0; k < N; k += m) {
+      let wr = 1,
+        wi = 0;
+      for (let j = 0; j < m2; j++) {
+        const tRe = wr * re[k + j + m2] - wi * im[k + j + m2];
+        const tIm = wr * im[k + j + m2] + wi * re[k + j + m2];
+        const uRe = re[k + j];
+        const uIm = im[k + j];
+        re[k + j] = uRe + tRe;
+        im[k + j] = uIm + tIm;
+        re[k + j + m2] = uRe - tRe;
+        im[k + j + m2] = uIm - tIm;
+        const tempWr = wr;
+        wr = wr * cosW - wi * sinW;
+        wi = tempWr * sinW + wi * cosW;
+      }
+    }
+  }
+}
+
+// Inverse FFT
+function ifft1D(re, im) {
+  // Conjugate
+  for (let i = 0; i < re.length; i++) im[i] = -im[i];
+  fft1D(re, im);
+  // Normalize and re-conjugate
+  const N = re.length;
+  for (let i = 0; i < N; i++) {
+    re[i] /= N;
+    im[i] = -im[i] / N;
+  }
+}
+
+// Apply ramp filter in frequency domain
+export function applyRampFilter(projection) {
+  const N = nextPow2(projection.length);
+  const re = new Float32Array(N);
+  const im = new Float32Array(N);
+  for (let i = 0; i < projection.length; i++) {
+    re[i] = projection[i];
+  }
+
+  fft1D(re, im);
+
+  for (let i = 0; i < N / 2; i++) {
+    const freq = i / N;
+    re[i] *= freq;
+    im[i] *= freq;
+    re[N - i - 1] *= freq;
+    im[N - i - 1] *= freq;
+  }
+
+  ifft1D(re, im);
+  return Array.from(re.slice(0, projection.length));
+}