If the specific paths are consistent except for the file names why not use constants for the paths and then just store the different sized images in the appropriate directories and reference just the file names in the database.
The main principle here is avoiding duplicate information, in the database and in your code. For the database you achieve higher normal form, and for the code you achieve DRY (Don't Repeat Yourself).
Assume you structure is something like
/home/user/site/images/original/
/home/user/site/images/small/
/home/user/site/images/medium/
/home/user/site/images/large/
you could use constants for that info. e.g.
PATH_ORIGINAL = /home/user/site/images/original/
PATH_SMALL = /home/user/site/images/small/
PATH_MEDIUM = /home/user/site/images/medium/
PATH_LARGE = /home/user/site/images/large/
Then in your code you could do something like
smallcar = PATH_TO_SMALL . car.jpg;
Or just insert the appropriate constant variable inside whatever query output you have for loading the images.
The added benefit is that you have one place to change paths if you need to tweak directory structures or move code between servers, rather than update a whole slough of database records, which might be more problematic and error prone.