What filter is this? (waveform monitor)

[FlimsyFeet]

I've been looking at this image:
http://www.geocities.com/mrtibsvideo/fixvhsoversharp_before_after.html
and I'd like to know how the waveform analysis shown above was actually created?

I've done a similar thing with the waveform monitor in the colortools virtualdub plugin, but it's just a load of dots, I'd like a solid graph like in the above example.

[communist]

Maybe this: http://www.avisynth.org/Histogram?

[marcellus]

IMHO is not a histogram in that image. I think it is the graphic representation of luma values for just one row of pixels (the row highlighted in the below image) - and not for the entire picture.I wonder what tool was used to obtain it.
Edit:
Heh, browsing that site I discovered that the tool is named LumaGraph and it does just that:

LumaGraph graphs the Luma of the video frame.

This filter operates on YUV sources only and is safe for interlaced material.

Usage - for best results:

# LumaGraph(
# [row number to plot],
# [Y position of graph])

[FlimsyFeet]

D'oh! You're right marcellus, I should have looked a bit harder.