AWarpsharp2/aWarp4

aWarp4 is designed for an even more custom warp-sharpening than aWarp allows. Unlike aWarp, this uses a 4x larger source clip than the edge mask. This is useful for improving the quality of the subpixel interpolation quality in the final step. Supersampling allows to produce a sharper result with lower depth, which equals to less deformations.

Syntax and Parameters

aWarp4 (clip, clip, int "depth", int "chroma")

clip   =

Input clip; must be exactly 4 times the width and height of the edge mask clip. The 4x upsampled clip should always be top-left aligned, take a look at the examples below.

clip   =

Edge mask clip; usually the input clip processed by aSobel and followed by aBlur.

If you want more stable results it's a good idea to do anti-aliasing and temporal filtering (if necessary) on the edge mask before passing it to the warping stage.

int  depth = 3

Strength of the final warping. Negative values result in warping in opposite direction, i.e. will blur the image instead of sharpening.

Range: -128 to 127

Note: Chroma channels are internally processed with depth/2.

int  chroma = 4

Processing mode for the chroma channels (U and V):

• 0 : fill with 0x80(128), output is grayscale.
• 1 : don't care - chroma will be trashed.
• 2 : copy chroma channels from the input clip.
• 3 : process chroma; create an edge mask from each chroma channel and use those to warp each chroma channel individually.
• 4 : process chroma; use the edge mask from the luma to warp the chroma channels.
• 5 : same as 3, but don't process luma.
• 6 : same as 4, but don't process luma.

Luma plane (Y) is always processed, except for mode 5 and 6 which simply copy the luma channel from the input clip.

Examples

Correct usage examples[1]:

• Using Spline36Resize to upscale:

input     = AviSource("Blah.avi")
input4x   = input.Spline36Resize(width*4, height*4, src_left=0.375, src_top=0.375)
edge_mask = input.aSobel(thresh=128, chroma=1).aBlur(blur=3, type=1, chroma=1)

aWarp4(input4x, edge_mask, depth=3, chroma=4)

The following example is written differently but is identical to the one above.

AviSource("Blah.avi")
aWarp4(Spline36Resize(width*4, height*4, 0.375, 0.375), aSobel().aBlur())

• Using nnedi3_rpow2 and Spline36Resize to upscale:

input     = AviSource("Blah.avi")
input4x   = input.nnedi3_rpow2(rfactor=2).Spline36Resize(width*4, height*4, 0.25, 0.25)
edge_mask = input.aSobel().aBlur()

aWarp4(input4x, edge_mask)

• Using nnedi3_rpow2 to upscale:

input     = AviSource("Blah.avi")
input4x   = input.nnedi3_rpow2(rfactor=2).nnedi3_rpow2(rfactor=2)
edge_mask = input.aSobel().aBlur()

aWarp4(input4x, edge_mask, depth=2)

• The 4x upsampled clip should always be top-left aligned, so Spline36Resize(width*4, height*4) or nnedi3_rpow2(rfactor=4) will not produce correct results.

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