k2mil@xxxxxxxxxxxxxx wrote: > I'm a colormunki photo owner, and i need to measure spectral characteristic > of white led light source. > I used "illumread -H led.sp" > There was no led.sp file as a result or resulting file has been 0 bytes long. > I used option: > 1) Measure direct illuminant > How can I force illumread to write .sp file? Hi, illumead is intended for measuring an illuminant and estimating its UV (Ultra Violet) content for the purposes of FWA/OBE correction. Since the ColorMunki is effectively UV filtered, it isn't suitable for this purpose. If you just want to measure the illuminant spectrum in the visible light range, use spotread, ie: spotread -e -H take a reading and then press 's' Enter filename (ie. xxxx.sp): etc. Note you can use -e or -a, depending on what you want to do. Graeme Gill.