best way to store image references in text using mysql/php -

i have text contains multiple images.

imagine like

i ((image1)) , ((image2)) , ((image3))

i storing text in table statements

st_id|text

i'm storing image path in images

img_id|path_on_disk

i store relation between text , image as

ti_id(pk) | st_id | img_id | imagenumber

here image number refers order image1, 2 , 3

so questions :

is format used in text best way point/refer image?
is database design efficient?
when i'm using in php, follow :

if fetched string has match (( , )) know have image, appropriate number , find in ti table using st_id , image_number else print text.

i think might not best way because going char char in long string , can affect efficiency. can better way if any?

Three