Anton, the chdk raw file contains the byte dump of the sensor and the sensor size is wider than the area of the final photo.
For example, my A650 ten-bits sensor size is 4104x3048 (15 636 240 bytes) and the photo size is 4000x3000. (15 000 000 bytes) just for the sensor information. The sensor oversize is to allow a non-exposed area which could be use to calculate non-exposed noise. DNG overhead add about 700 KB to include thumbnail and photografic information. That means a total of, about 15 716 622 bytes
No magic solution for me to optimize storage since in raw (15 636 240 B) or in dng (15 716 662 B) is about the same thing in term of SD blocks. And there is no option concerning the jpg file, it's still and always there.
P.S.: Concerning the red powder, some day, nearby, someone will deliver a right color profile for the SX130
