PSPad uses for autodetection first about 10k of text. Because in your file is encoded image and few UTF-8 encoded chars is on the end, PSpad won't detect it.
Try to put some UTF-8 encoded chars before image. Header information isn't relevat for autodetection, PSpad isn't not a web browser who intepret code content. You can anytime change code page in the menu Encoding to UTF-8 and reload file (Ctrl+R) If you have enabled save file state options, PSPad will remember code page for this file for you. -- <https://forum.pspad.com/read.php?4,71479,71480> PSPad freeware editor https://www.pspad.com
