In the list of raster pixel data types that are available with GDAL, the "smallest" types are Bytes, UInt16 and Int16. I would like to store integers from 0 to 100 in the smallest image type, but with the constraint of using -1 and -2 for NoData value and other specific value. GDAL Bytes are unsigned, so the smallest type would be Int16. http://www.gdal.org/gdal_8h.html#a22e22ce0a55036a96f652765793fb7a4

I use this type to create rasters, with the Rasterize function in Python bindings.

Do you know if there is a trick to use signed Bytes ?


This is an interesting problem. To my knowledge, GDAL does not support interpretation of signed 8-bit data. Even raster formats that can handle signed bytes SDAT, for instance are coerced to handle GDT_Byte I think...

The obvious solution to your underlying problem is to use a nodata value like 255 if you really care about the file storage size. Otherwise use a signed 16-bit image and some compression if the format supports it. You may find it plenty suitable.

  • Thanks a lot for your answer. I actually used a 16bit image, but due to the large size I guess we'll switch to Bytes with 255 for NoData, which is the simplest way. Anyway, it would be an interesting feature for future of GDAL to have signed Bytes ! – Daemons Jan 25 '18 at 15:29

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.