public void setDownSamplingFactor(float downSamplingFactor) {
        this.downSamplingFactor = downSamplingFactor;
        if (assetManager != null) // dirty isInitialised check
            reInitFilter();
    }
Sets the downSampling factor : the size of the computed texture will be divided by this factor. default is 1 for no downsampling
A 2 value is a good way of widening the blur

@param downSamplingFactor the desired factor (default=1)
jme3-effects/src/main/java/com/jme3/post/filters/BloomFilter.java