The effects on the frame, above or below the predetermined threshold, are not terminated, it decreases gradually. The effect curve is shown on the left. If we affect only on the shadows then to the position of the slider bar the effect is full, further it decreases and continues to decrease, disappearing only at the range border. Near the highlights or shadows(depending on what we have chosen) practically there is no effect and it doesn't become evident immediately, cos(x)=0