capturing at double resolution(?)

[greenbag]

Just wondering, I came across 'video enhancer'... video cleaning proggie that uses vdub filters.

The editor has option of resizing 720x480 to 1440x960 before applying filters... then resized back to 720x480. In theory, this sounds good, but after thinking about it, wouldn't it also enlarge any noise/artifacts, or is that the idea?

Also, if this technique works, would it also be a good idea to 'capture' in 1440x960 right from the start?


tia,

gb

[guns1inger]

Capturing at double resolution has merit only if the source is good enough.

Enlarging before filtering, then resizing down again has little benefit for most filters.

That isn't to say it won't help in some situations. Some 3D renderers work in a similar fashion, rendering in multiples of the final required resolution, then resizing down. It allows for extra detail to be added that may aid the final image. However most filtering for image correction doesn't require the extra resolution, and many filters are designed to work on standard DCT block sizes, which are lost if the image is resized up first.

[greenbag]

thanks guns1inger...

Wasn't sure if it would actually benefit. I'll play around with it and see if there's a difference.

Out of curiosity, would lancosresize (think it's called) be just as good as this 'MSU Super Resolution filter' (commercial-ware only)? A 45min clip is taking 17hrs to upsize in 'video enhancer'... thinking avisynth would be quicker.


thanks

[guns1inger]

I prefer Lanczos4Resize myself.

The short answer : it depends on the quality of the source and the amount of upsizing. Standard avi to DVD upscaling probably doesn't warrant VideoEnhancer and the time required. Lanczos4Resize in avisynth, with a small amount of aSharp applied for good measure, should give you as good a result.

Upscaling VCD/YouTube to DVD, or standard avi or DVD to 720p, would certainly benefit from the methods that VideoEnhancer uses.

[greenbag]

yep... Lanczos4Resize only took just under 3hrs... and gave a better 'clearer' pictrure.

Problem I found though, is certain filters will not work with a 1440x960 resolution... both MSU_Denoise and MSU_OldColourRestoration will crash 2 seconds into the procedure. Some denoisers will work, such as the 2d denoiser, but I prefer the MSU filter.

Also, seems video enhancer actually upsizes after the filter process... not upsize/filter/downsize as I thought before.

Something else I found... virtualdub will not capture at 1440x480 (2x standard 720x240 vdub capture), and neither will ati's mmc capture... unless it's just the ati aiw, maybe hauppauge would be different.

It's too bad... I definately see the benefits of cleaning at a larger resolution. Not only do you have a better look at what needs to be cleaned, but, 'noise' seems to break up and dissipate the larger it gets, which 'should' be easier to clean.

[Soopafresh]

You can use AVIsynth plugin nnedi http://forum.doom9.org/showthread.php?t=129953 to upsize to 2X in both directions, apply filters, then downsize to desired resolution.

loadplugin("nnedi.dll")

avisource("your_file.avi")
Converttoyv12()
nnediresize_YV12()
fft3dfilter(sigma=2, degrid=1)#or prefered denoiser
Bicubicresize(720x480)



function nnediresize2x(clip c, bool pY, bool pU, bool pV)
{
	v = c.nnedi(dh=true,Y=pY,U=pU,V=pV,field=0).turnleft()
	v = v.nnedi(dh=true,Y=pY,U=pU,V=pV,field=0).turnright()
	return v
}

function nnediresize_YUY2(clip c)
{
	cy = c
	cu = c.utoy()
	cv = c.vtoy()
	cy = nnediresize2x(cy,true,false,false)
	cu = nnediresize2x(cu,true,false,false)
	cv = nnediresize2x(cv,true,false,false)
	return ytouv(cu,cv,cy)
}

function nnediresize_YV12(clip c)
{
	return nnediresize2x(c,true,true,true)
}

[greenbag]

thanks Soopafresh

just grabbed the filter and thread, will give a try


cheers

[Soopafresh]

Keep an eye on softening from the upsizing. You might have to perform some sharpening before you bring the size back down.