Comparing 1080/720--A couple questions

[linyx]

As you know, Blu-Ray is good looking, but generally not 1080p good:). So, I've been using a script like this to "compare" the quality at 1080p and 720p before encoding, but I would like to ask those that are smarter than me at this stuff and see if there is something better I could be doing.:p

#Source
Spline36Resize(1920,1080) #make sure that it is 1080x1920, should I leave it "as is"?
Source = SelectRangeEvery(2400,10) #Select 10 frames every 100 seconds or 1 minute 40 seconds.
Second = Source.Spline36Resize(1280,720).Spline36Resize(1920,1080) #Resize it down to 720p and back up again. Using Spline36Resize since it is generally considered "neutral"
SSIM(Source,Second,"results.csv","averageSSIM.txt",lumimask=false) #create a log to compare them via SSIM, generally lower values mean higher quality ( < 0.99 is great, < 0.995 is alright, > 0.995 is bad)

Would cropping beforehand produce a more accurate result? Would PSNR be a better way to accurately compare them?
Anything else you want to suggest?

Thanks a ton in advance!!!

[Keiyakusha]

By the way, about this metrics is a good question. if someone can answer it, please tell about difference about applying this method to Anime and Live Action. If there is some differences at all. I guess it's not sufficient for anime since flat regions probably won't result high ssim drop. (Also lets not forget that at least half of the anime on BD is a some kind of 720p->1080p upscales to begin with)

[10L23r]

the upscaling part should be the upscaler used on playback, which probably isn't spline36.

but that shouldn't matter too much

oh btw, i think you got the ssim thing totally wrong. higher is better
and 0.995 is twice as "good" as 0.990; 0.9 is twice as "good" as 0.8

[linyx]

oh btw, i think you got the ssim thing totally wrong. higher is better
and 0.995 is twice as "good" as 0.990; 0.9 is twice as "good" as 0.8
In normal cases yes, that would be right; but in this case the greater the difference (lower ssim), the more "detail" is lost when going to 720, therefore the 1080 version has more detail.