If the characters are not clear, it's your material itself. You should search for a high-quality picture.
It is ok to use it as material.
If it is a text part, I'm not sure what caused it.
But you can try using other image processing software, such as PS.
Set the appropriate font and it will be clear when it comes out.
I can sharpen this picture for you, but I don't think the effect will be obvious.