base64 to tiff:

import base64

text_base64 = 'SUkqAAgAAAASAP4ABAABAAAAAAAAAAABAwABAAAACgAAAAEBAwABAAAACgAAAAIBAwADAAAA5gAAAAMBAwABAAAAsoAAAAYBAwABAAAAAgAAABEBBAABAAAAgAMAABIBCQABAAAAAQAAABUBAwABAAAAAwAAABYBAwABAAAAKAAAABcBBAABAAAAPwAAABoBBQABAAAA7AAAABsBBQABAAAA9AAAABwBAwABAAAAAQAAACgBAwABAAAAAgAAADIBAgAUAAAA/AAAAD0BAwABAAAAAgAAAGmHBAABAAAAEAEAAF4BAAAIAAgACABIAAAAAQAAAEgAAAABAAAAMjAxOTowNzoyMyAyMTozNDoxOQAGAACQBwAEAAAAMDIyMQGRBwAEAAAAAQIDAACgBwAEAAAAMDEwMAGgCQABAAAAAQAAAAKgCQABAAAACgAAAAOgCQABAAAACgAAAAAAAAAGAAMBAwABAAAABgAAABoBCQABAAAASAAAABsBCQABAAAASAAAACgBCQABAAAAAgAAAAECBAABAAAArAEAAAICBAABAAAA1AEAAAAAAAD/2P/gABBKRklGAAEBAAABAAEAAP/bAEMABQMEBAQDBQQEBAUFBQYHDAgHBwcHDwsLCQwRDxISEQ8RERMWHBcTFBoVEREYIRgaHR0fHx8TFyIkIh4kHB4fHv/bAEMBBQUFBwYHDggIDh4UERQeHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4eHh4eHv/AABEIAAoACgMBIgACEQEDEQH/xAAXAAADAQAAAAAAAAAAAAAAAAAABwgJ/8QAIBAAAgICAgMBAQAAAAAAAAAAAgMBBAUGBxEACCETEv/EABQBAQAAAAAAAAAAAAAAAAAAAAD/xAAUEQEAAAAAAAAAAAAAAAAAAAAA/9oADAMBAAIRAxEAPwBi60fFuU1XB5beI0a3tWVxGMv2RzeECzk77nALXymDn9LIsE4UkEjIrMJWMH/H4hOfJXsNzHq3Iuy6xhd0cnF4jL2qFJbqVawwEpcS1wTWrJjCgRjszIiKfszMzM+Htlu+6at7CbVhdY2/YMHi1NQ5dLHZJ1ZAG2sprThYFAwRsMzKeuyIyKe5mZ80MoVKtCjXo0ayatSsoUoQlcAtQDHQgIx8EYiIiIj5ER4H/9l4nPv//z8DAwMjIyMDKvgPFgeSQCkIGxnABTGl4ArgsnDFyAwi9eKRRXMYhItmL5p34Gpw+QhTI7J2AOTAPvUA'

bytes_base64 = text_base64.encode()
data = base64.b64decode(bytes_base64)
open('image.tiff', 'wb').write(data)

tiff to base64 and html:

import base64

data = open('image.tiff', 'rb').read()
bytes_base64 = base64.b64encode(data)
text_base64 = bytes_base64.decode()

print(text_base64)

html = '<img src="data:image/tiff;base64,' + text_base64 + '">'
open('output-tiff.html', 'w').write(html)

Probably most browsers can't display tiff so file .html may display broken image. You would have to save it from page to file and then you can see tiff.

This is image used in examples but here in png format:

EDIT: example with the same image but in png format. This html will display image in every browser.

# base64 to png

import base64

text_base64 = 'iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAAAAACoWZBhAAAAMklEQVR4nEXNwQkAMBACwfFI/y2bxwXia8FFUwF1pCCNJTIIwaD04ctsKRyaldI/9i8u1iwOE6FA880AAAAASUVORK5CYII='

bytes_base64 = text_base64.encode()
data = base64.b64decode(bytes_base64)
open('image.png', 'wb').write(data)

# png to base64 and html

import base64

data = open('image.png', 'rb').read()
bytes_base64 = base64.b64encode(data)
text_base64 = bytes_base64.decode()

print(text_base64)

html = '<img src="data:image/png;base64,' + text_base64 + '">'
open('output-png.html', 'w').write(html)