Add function that applies different filters

public/fbp.js

@@ -90,3 +90,57 @@ export function applyRampFilter(projection) {
   ifft1D(re, im);
   return Array.from(re.slice(0, projection.length));
 }
+
+export function applyFilter(projection, type = "ramp") {
+  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 normFreq = i / N;
+    const ramp = normFreq;
+
+    let filter = 1;
+
+    switch (type) {
+      case "ramp":
+        filter = ramp;
+        break;
+      case "shepp-logan":
+        const sinc =
+          normFreq === 0
+            ? 1
+            : Math.sin(Math.PI * normFreq) / (Math.PI * normFreq);
+        filter = ramp * sinc;
+        break;
+      case "hann":
+        filter = ramp * (0.5 + 0.5 * Math.cos(Math.PI * normFreq));
+        break;
+      case "hamming":
+        filter = ramp * (0.54 + 0.46 * Math.cos(Math.PI * normFreq));
+        break;
+      case "cosine":
+        filter = ramp * Math.cos((Math.PI * normFreq) / 2);
+        break;
+      case "none":
+        filter = 1;
+        break;
+      default:
+        console.warn(`Unknown filter type: ${type}. Defaulting to ramp.`);
+        filter = ramp;
+    }
+
+    re[i] *= filter;
+    im[i] *= filter;
+    re[N - i - 1] *= filter;
+    im[N - i - 1] *= filter;
+  }
+
+  ifft1D(re, im);
+  return Array.from(re.slice(0, projection.length));
+}