none said:

dark_jedi wrote: what in the world are you trying to accomplish with this?

Initially, this is being done to spot changes in the recent set. I don't have the visual knowledge of these films as many here do. Never watched them as a kid as we didn't have a VCR or laserdisc. So although i'm interested in the changes, I can't watch and spot, hey that's off. But as everything is digital can approach finding changes from a mechanical perspective. Let the computer figure it out. But right now don't know how to get the computer to spit out the information.

Here's the graph i'd like to get: (no spit takes!)

Taking two sources and 'Difference' blending mode them, returns mostly black screen, so the chart would flat line most of the time, and the spots where a revision has occured will spike the chart. Then just go to that spot in the video and see what's causing the anomaly. That's the identifying part.

Just my initial thoughts about how you might be able to produce this.

Using an Avisynth script along these lines:

source1=[HD broadcast].converttorgb()
source2=[BD rip].convertorgb()
Subtract(source1, source2) # the video will now be totally grey, unless there are any differences between the two sources
Levels([yada yada]) # may be required to tweak levels or saturation to make changes more visible in the following steps
PointResize(1,1) # this basically produces a single pixel by averaging every pixel in the frame
DumpPixelValues("RGB", "(0,0)")

Now open the file dumppixelvalue.log in Excel, and manipulate (convert hex to decimal, etc.) to produce your graph. It will look slightly different because the default will be 128, with differences shown as either higher or lower than this mid point.