SDTC (Simplified Dynamic Threshold) isn’t defined in the twain spec. It is probably a custom capability for the device. Ask VintaSoft for information on setting custom capabilities. Or you could try using CustomDsData and hacking the stream you send back in… seach the forumn for ‘hack’. if you go with setting the custom cap directly you might need a little info from the device vendor, like the acceptable values and if you ever get someone from the device vendor to talk to you that seems to understand what a castom capability is ask them fór their twain header as it will be of use when you run into the next .custom cap.