Is there a way to add collision onto a 1-part picture?

i’m trying to make a collision between walls so players don’t just walk through everything. I have searched though the internet but it all talked about using tiles for maps, but i’m using pictures. I am running out of options and i don’t even think its possible. There is no extra parts to the picture, its just 1 part, dragged and dropped onto the scene. Isn’t there a way to add collision with like a drag box? something like that can help me

the picture i’m using is something like this

,i created the map of the world my player can walk in using pixel art, and i want it so the player cant just walk through walls that they cant walk through. I’ve tried using tiled but it wouldn’t work, I’ve searched all over the internet for answers but i never got a answer. How can i add collision to a 1 part picture??

this is what i’m trying to make a collision on

i cant what is happening;
but if u mean collision u can always create your own objects and add boxCollider2D and set the values as u want like a wall then add a Rigidbody2D ;