I want to alter the image data of a base64 image. Altering is in this case encrypting the image data but it can be replace by toUpperCase() for simplicity's sake. I get the image data with this code snippet :

let originalImage = myBase64Image
let imageData = originalImage.replace(/^data:image\/[a-z]+;base64,/, "");
imageData = imageData.toUpperCase()

Altering the imageData does not result in the changing of the original image data. I was wondering if there way to bring imageData back to a full base64 image that I can use in an html element for example. Thanks in advance.