The purpose of this paper is to establish an image processing method which can be applied to the two layered spun yarns. The cross-section of the two layered spun yarn consists of N-fiber (I, dark), P-fiber (II, middle brightness) and the background (III, bright). In the usual image processing method, the boundary region between I and III components is identified to be II component by mistake. The new method, which has been proposed in this paper, consists of ; (a) a method which distinguish the I /III boundary region from the II component region, and (b) a threshold by thich the I / III boundary region is divided into I and III components. It has been shown that : (1) By the use of this new method, the fross-section of the two layered spun yarn can be divided into three components accurately. (2) The threshold brightness can be rapidly determined by referring to the average difference distribution and to the intensity histogram.

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Velocity characteristics of weft yarns during weft inserition in an air jet loom are investigated experimentally. Velocities at an intermediate point between a main-nozzle and a gripper are measured by using a laser-doppler velocimeter which is designed for fluids. In addition, mean velocities of yarn at the leading end and yarn-tension fluctuations are measured and compared with each other.
According to those results, transient velocity fluctuation which has significant relation to tension fluctuation takes place at both the start and the end stage of the weft insertion. Especially in the end stage of insertion, velocity fluctuation is affected by looseness of the propelling yarn.
Furthermore, the behavior of velocity fluctuations under the various conditions of weft insertion is discussed in detail.

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For examining to spun yarn at untwisting nuder a constant load, we developed an apparatus for evaluation of untwisting behavior. Spun yarn (cotton 100%, 40 Ne, single yarn) and finished yarn were tested.
The results demonstrated each different behaviors. We think that these difference of behaviors were caused by process bleaching, dyeing, and sizing.
Next, we tried to evaluate weaving efficiency of sizing yarn and to test the poperties of spun yarns.
It becomes clear that effect of sizing can be estimated by maximum untwist turns, and maximum expansion under the test of nutwisting.

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