Make generated singogram easier to see

This commit is contained in:
Peter Stockings
2025-05-17 09:52:48 +10:00
parent ad74375567
commit 26e860d168
2 changed files with 36 additions and 25 deletions

View File

@@ -230,6 +230,7 @@ export const UploadImageComponent = {
src: this.sinogramUrl,
alt: "Sinogram",
class: "rounded shadow max-w-full h-auto mx-auto",
style: "width: 100%; max-height: 300px;",
}),
]),

View File

@@ -18,51 +18,49 @@ export async function generateSinogram(
for (let angle = 0; angle < angles; angle++) {
const theta = (angle * Math.PI) / angles;
// 🔁 Call visual overlay for this angle
if (drawAngleCallback) drawAngleCallback(theta);
// (Optional: add delay for animation)
await new Promise((r) => setTimeout(r, 0.01));
// Clear canvas
ctx.clearRect(0, 0, size, size);
// Transform and draw rotated image
ctx.save();
ctx.translate(size / 2, size / 2);
ctx.rotate(theta);
ctx.drawImage(image, -image.width / 2, -image.height / 2);
ctx.restore();
// Read pixel data
const { data } = ctx.getImageData(0, 0, size, size);
// Sum brightness vertically (simulate X-ray projection)
const projection = [];
for (let x = 0; x < size; x++) {
let sum = 0;
for (let y = 0; y < size; y++) {
const i = (y * size + x) * 4;
const gray = data[i]; // red channel (since grayscale)
sum += gray;
sum += data[i]; // grayscale from red channel
}
projection.push(sum / size); // normalize
projection.push(sum / size);
}
projections.push(projection);
}
// Create sinogram canvas
const isHorizontal = angles >= size;
// Create rotated canvas accordingly
const sinogramCanvas = Object.assign(document.createElement("canvas"), {
width: size,
height: angles,
width: isHorizontal ? size : angles,
height: isHorizontal ? angles : size,
});
const sinCtx = sinogramCanvas.getContext("2d");
const imgData = sinCtx.createImageData(size, angles);
const imgData = sinCtx.createImageData(
sinogramCanvas.width,
sinogramCanvas.height
);
for (let y = 0; y < angles; y++) {
for (let angle = 0; angle < angles; angle++) {
for (let x = 0; x < size; x++) {
const val = projections[y][x];
const i = (y * size + x) * 4;
const val = projections[angle][x];
const px = isHorizontal ? x : angle;
const py = isHorizontal ? angle : x;
const i = (py * sinogramCanvas.width + px) * 4;
imgData.data[i + 0] = val;
imgData.data[i + 1] = val;
imgData.data[i + 2] = val;
@@ -95,7 +93,18 @@ export async function reconstructImageFromSinogram(
sinogramImage.height
).data;
size = sinogramImage.width; // match size to sinogram resolution
// Detect orientation
let width, angles;
const isVertical = sinogramImage.height > sinogramImage.width;
if (isVertical) {
angles = sinogramImage.width;
width = sinogramImage.height;
} else {
angles = sinogramImage.height;
width = sinogramImage.width;
}
size = width;
const outputCanvas = Object.assign(document.createElement("canvas"), {
width: size,
height: size,
@@ -104,17 +113,18 @@ export async function reconstructImageFromSinogram(
const accum = new Float32Array(size * size);
const center = size / 2;
const angles = sinogramImage.height;
const width = sinogramImage.width;
for (let angle = 0; angle < angles; angle++) {
const theta = (angle * Math.PI) / angles;
let projection = [];
for (let x = 0; x < width; x++) {
const i = (angle * width + x) * 4;
const i = isVertical
? (x * angles + angle) * 4 // transposed layout
: (angle * width + x) * 4; // normal layout
projection.push(sinogramData[i]);
}
if (useFBP) {
projection = applyRampFilter(projection);
}
@@ -122,7 +132,7 @@ export async function reconstructImageFromSinogram(
for (let y = 0; y < size; y++) {
for (let x = 0; x < size; x++) {
const x0 = x - center;
const y0 = center - y; // flip y
const y0 = center - y;
const s = Math.round(
x0 * Math.cos(theta) + y0 * Math.sin(theta) + width / 2
);
@@ -133,7 +143,6 @@ export async function reconstructImageFromSinogram(
}
if (onFrame) {
// normalize and draw current frame
let maxVal = 0;
for (let i = 0; i < accum.length; i++) {
if (accum[i] > maxVal) maxVal = accum[i];
@@ -154,6 +163,7 @@ export async function reconstructImageFromSinogram(
imageData.data[i * 4 + 2] = b;
imageData.data[i * 4 + 3] = 255;
}
outputCtx.putImageData(imageData, 0, 0);
await new Promise((r) => setTimeout(r, 1));
onFrame(angle, outputCanvas.toDataURL());