AFAIK there is no such format (in any Gimp version).
If you can subtract you can round to integer, and even round to gamma corrected integer.
There is a "RAW" Gimp format in the load selector where you provide plain data and tell how to interpret the data:
An alternative is the TGA format which is mostly plain bitmap data with a simple header giving width/height.
If you can subtract you can round to integer, and even round to gamma corrected integer.
There is a "RAW" Gimp format in the load selector where you provide plain data and tell how to interpret the data:
An alternative is the TGA format which is mostly plain bitmap data with a simple header giving width/height.