How to send a base64 image to Bedrock via ConverseCommand as bytes

I'm trying to upload an image to AWS Bedrock Claude model using the ConverseCommand (in @aws-sdk/client-bedrock-runtime 3.699.0).

I have the base64 version of image (eg https://yulvil.github.io/gopherjs/02/)

According to the documentation, it requires the bytes as a Uint8Array, so I've tried

1. bytes: new Uint8Array(Buffer.from(img, 'utf-8'))
2. bytes: Buffer.from(img, 'utf-8')
3. bytes: new TextEncoder().encode(ing)

None seem to work having error ValidationException: The model returned the following errors: messages.0.content.1.image.source.bytes: Invalid image input

What am I missing?

const {
  BedrockRuntimeClient,
  ConverseCommand,
} = require("@aws-sdk/client-bedrock-runtime");

const modelId = "anthropic.claude-3-haiku-20240307-v1:0";

let conversation = [];

const describeImage = async () => {
  const client = new BedrockRuntimeClient({
    region: "us-east-1",
    credentials: {
      accessKeyId: process.env.AWS_ACCESS_KEY_ID,
      secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY,
    },
  });

  let content = [];

  const img = “data:image/png;base64,...”

  content.push({
    image: {
      format: "png",
      source: {
        bytes: img,
      },
    },
  });
  content.push({ text: “Describe the given image” });
  conversation.push({
    role: "user",
    content,
  });

  try {
    const response = await client.send(
      new ConverseCommand({
        modelId,
        messages: conversation,
      })
    );
    return response.output.message.content[0].text;
  } catch (err) {
    console.log(`ERROR: Can't invoke '${modelId}'. Reason: ${err}`);
  }

describeImage();