Uploading Base64 file to S3 signed URL – Amazon web services

I need to upload an image to S3 using signed URL. I have the image in a base64 string. The below code runs without throwing any error, but at the end I see a text file with base64 content in the S3, not the binary image.

Can you please point out what I am missing?

Generate Signed URL (Lambda function JavaScript)

  const signedUrlExpireSeconds = 60 * 100;
  var url = s3.getSignedUrl("putObject", {
    Bucket: process.env.ScreenshotBucket,
    Key: s3Key,
    ContentType: "image/jpeg",
    ContentEncoding: "base64",
    Expires: signedUrlExpireSeconds,
  });

Upload to S3 (Java Code)

HttpRequest request = HttpRequest.newBuilder().PUT(HttpRequest.BodyPublishers.ofString(body))
        .header("Content-Encoding", "base64").header("Content-Type", "image/jpeg").uri(URI.create(url)).build();

HttpResponse<String> response = httpClient.send(request, HttpResponse.BodyHandlers.ofString());

if (response.statusCode() != 200) {
    throw new Exception(response.body());
}