XF 2.2 custom fields callback

[Robert9]

I can add a callback to a customfield; example

Input: BLUE CAR
callback > lowercase input > blue car
save blue car

but how can I do the opposite way and show the field value uppercase?

is there another fix function to say:

function_for_output
value from field > uppercase value > show value

and is there a function to do the same to the edit field?

function_for_edit
value from field > uppercase value > show value in form field