Modifying Images on Webpage with Web Extension - javascript

I am currently working on a web extension that goes through all the images in the current webpage and blurs them. I have created a backend API that accepts a base64 encoded string of an image and returns the encoded string for the blurred image. My current issue is that I can't find a way to access all the images on the current webpage and get their base64 encoded string through javascript. How can I do this?
The intended architecture of the extension is as follows: the javascript file reads all the images on the webpage and encodes them into a base64 string, which is passed to the backend API. The API then blurs the image and returns a base64 encoded string of the blurred image. The javascript then decodes the string and replaces the original image with the blurred image.
Any help would be greatly appreciated.
I have tried going through all the image tags in the html of the webpage and fetching their urls, however this does not allow me to get the base64 encoding of the image(s). I would like to write a function that takes in the url to an image and returns the base64 encoding.

Related

Show .tiff/.tif image on chrome from its base64 encoded string with Javascript/Reactjs or convert it to any other (png/jpeg) format and display on UI

I have a base64 encoded string of a .tiff image that I get from the backend. If I decode it and then create a blob url, It works fine on Internet Explorer (by using on src of img tag).
I am not able to show it on Chrome. I have read some answers related to it where people are saying it is not supported on Chrome.
There are some libraries like https://www.npmjs.com/package/tiff-to-png but they require an image to be stored somewhere and then use it to convert. I only have a base64 string of the image. I am not able to find any solution online. My UI is built with ReactJs and backend is on Node.
On backend, I have a buffer of the .tiff image which we are converting to base64 to send it to UI. If we can do anything on buffer, that is also possible. Please help.

How to change byte array taken from json to image [duplicate]

I'm writing a web page in HTML/JavaScript. I'm downloading an image from my backend using AJAX. The image is represented as raw byte array, not an URL, so I can't use the standard <img src="{url}"> approach.
How do I display the mentioned image to the user?
Try putting this HTML snippet into your served document:
<img id="ItemPreview" src="">
Then, on JavaScript side, you can dynamically modify image's src attribute with so-called Data URL.
document.getElementById("ItemPreview").src = "data:image/png;base64," + yourByteArrayAsBase64;
Alternatively, using jQuery:
$('#ItemPreview').attr('src', `data:image/png;base64,${yourByteArrayAsBase64}`);
This assumes that your image is stored in PNG format, which is quite popular. If you use some other image format (e.g. JPEG), modify the MIME type ("image/..." part) in the URL accordingly.
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How to convert a byte array into an image?

How to embed a large image with data uri

I currently have a large base64 image uri (Received via external JS script) and want to embed it into the HTML page. I did this successfully locally but now that it pulls it from another place it seems to not work, it loads part of the image then says "Image corrupt or truncated. URI in this note truncated due to length." This occurs both just in the <img> tag and using <canvas>, is there any way to load large images from uri? Or another way to display images from a base64 string?
What doesn't make sense is it works fine if I specify the base64 string as a javascript variable, but when I include it as a variable in an external script, it gives this error. Would breaking up the string then putting it back together fix this?
You shouldn't use data-URLs for huge files.
You could try to convert your base64 URL into a blob object and the blob object into a temporary blob url using the following javascript function:
function dataurlToBlobUrl(url){
var parts = url.split(',',2);
var mime = parts[0].substr(5).split(';')[0];
var blob = b64toBlob(parts[1],mime);
return URL.createObjectURL(blob);
}
And the b64toBlob function from here:
https://stackoverflow.com/a/16245768/5406901
Just make sure to use "URL.revokeObjectURL" whenever you no longer need the blob url.

Encrypt a Base64 encoded image into another valid Base64 encoded image

I am wanting to take a currently base64 encoded image and use a short hash say "84dskh" to "encrypt" the image into another perfectly valid base64 encoded image.
The original image does not have to be base64 encoded, ultimately I want a encrypted image of the original, but have it still be a valid image I could display in a img tag: <img src="myimage" />.
Preferably using javascript.
To encrypt the image, you would save it as a string (there may be limits there), and then when loading the image into the HTML document, use a decrypt method. Here is a related question. You may also find this library helpful (suggested within an answer).

Decode base64 image link

I'm converting the page to canvas and then canvas to the image. Function convertCanvasToImage returns image link as base64 encoded link. Looking for a solution to decode it cause I'll need that later and would be easier.
Encoded image starts with data:image/png;base64,longString.
I tried
var decodedData = window.atob(n); and http://www.webtoolkit.info/javascript-base64.html
But it returns chinese characters.
Also, I tried sending the encoded string to the server via ajax and then try with base64_decode. Still, I get odd output.
Any reference or solution how to decode base64 png image and get normal URL of the image? Is it possible for a canvas to return normal URL not encoded?

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