This is ikat, which I always think of as a fuzzy design. Ikat is when the weft threads on a loom are dyed, then manipulated a bit so the edges of a design are not crisp. There is also double-ikat, which is when both the warp & weft are dyed & manipulated. Whitney Matalone has posted a riveting time-lapse video here.
Ikat is called kasuri in Japan and is usually just done w/ two colors there. Typically indigo & white or, less often, brown & white. But you can see that in Indonesia, it's done with many different colors. Either way, I find ikat pretty amazing. As with batik, it takes a lot of planning & prep, but I think you'll agree it pays off in the end!
|An ikat sash. The threads are not as fine as in|
the sarong, making a less detailed pattern.