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Old 29th March 2005, 03:39   #7  |  Link
Didée
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Join Date: Apr 2002
Location: Germany
Posts: 5,389
Backwoods: Yes. but you've hawk's eyes, and are probably trying on cartoon or animee. Try bicubic(25%, 0.33,0.33).bicubic(100%, 1.0,0.0) instead of lanczos

I'm too tired right now to work it all through. But please, just try the following:

- raise strength in layer() from "10" to, say, "32" or "64"

- *do check* the result via interleave() & histogram(mode="levels") as I said.

Then you will see what really is going on. Nothing against the method. It is a simple method, working very fast. And so is the result: fast and, well, simple.
Put shortly, the method is nothing more than a combination of {reduction of dynamic range} plus {unsharp masking}.
In particular, one is loosing blacks and whites.


BTW, using MaskTools, one cane do exactly the same as one-liner:

without any blurring (ultrafast):
Code:
strength = 10

yv12lut(source, "x 128 - 128 x - "+string(strength)+" 128 / * + 128 +", U=2,V=2)

# interleave( source, last ) .histogram(mode="levels")
with custom blurring:
Code:
strength = 10

blurred = source.blur(0.2,0.2)
#blurred = source.bicubicresize(source.width/16*4,source.height/16*4)
# \              .bicubicresize(source.width,source.height, 1.0, 0.0)

yv12lutxy(source,blurred,"x 128 - 128 y - "+string(strength)+" 128 / * + 128 +",U=2,V=2)

# interleave( source, last ) .histogram(mode="levels")
That's exactly the same, with following exceptions:

- chroma is not touched (original script washes out colors, too)
- it is faster
- it works in YV12
- it is more precise: one-step-operation, hence no rounding errors.

Also, try both blurring versions of the 2nd scriptlet. You'll notice that the first one (weak blurring @ 0.2) destroys the homogenity of a frame's histogram, and the output also looses sharpness. With the gaussian blurring, the histogram stays smooth, and the output doesn't loose sharpness.

Good night then ... /*snoozes away*/
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