1. Image signal forming means, comprising means for forming a first analog envelope-forming signal, the effective envelope amplitude of which varies in time as a function of a sectional outline bounding a portion of a first area desired to be imaged, means for forming a second analog envelope-forming signal in time-overlapping timed phase relation with said first signal and the effective envelope amplitude of which varies in time as a function of a further sectional outline bounding a portion of a respective second area desired to be simultaneously imaged, means for adding said first and second signals and for forming as a function thereof a composite envelope-forming signal the effective envelope of which varies in time as a function of both of said first and second areas, means for forming a common time reference ramp trace-sweep signal in time-overlapping relation with, and for use in common with, said composite envelope-forming signal to effect trace movement in a direction transverse to trace movement effected by said composite envelope-forming signal, means for generating an A.C. carrier signal varying through multiple repetitive cycles within the time span duration of one occurrwence of said common time ramp reference signal, and means for producing an envelope image-forming signal formed of repetitive cycles corresponding in frequency to said A.C. carrier signal, the successive peak-to-peak amplitude of which repetitive cycles is a function of said composite envelope-forming signal.