Sprite is not displayed clearly. (See the image please)

sprite_clear

Please see the image in full size. Why is it happening?

var progressBar = new cc.ProgressTimer();        
        progressBar.setSprite(new cc.Sprite(this.spriteFrameCacheGeneral.getSpriteFrame("progressbar.png")));
        progressBar.setType(cc.ProgressTimer.TYPE_RADIAL);
        progressBar.setPercentage(100);
        //progressBar.midPoint = cc.p(0.5, 0.5);
        progressBar.setAnchorPoint(cc.p(0.5, 0.5));
        progressBar.x = this.size.width / 2;
        progressBar.y = this.size.height / 2;
        progressBar.setColor(cc.color(238, 0, 133));        
        
        this.addChild(progressBar);