noizuy

from collections.abc import Callable
import vapoursynth as vs
core = vs.core
from vstools import depth, get_peak_value, get_lowest_value, get_y

def lee_banding_mask(clip: vs.VideoNode, bits: int = 2, threshold: int | None = None, edge_detection: Callable = core.std.Sobel):
    """
    False contour detection via bit depth reduction. The idea is (overly) simple: Re-quantize and find difference to input, calculate the gradient, and mark gradients under a threshold as false contours.
    Naturally, this only works on content that isn't naturally flat.

noizuy

# False contour detection is described in http://dx.doi.org/10.1109/ICCE.2006.1598468
# Smoothing is described in http://dx.doi.org/10.1109/TCE.2010.5506014
# Direction estimation is described in http://dx.doi.org/10.1109/TCE.2006.1706513
#
# These papers seem to all be a part of the same project.
# Their end result uses the original false contour detection and uses a NN along with the directional smoothing used here to choose which pixels to smooth and how.
# Keep in mind it works in your given image's bit depth.
#
# Usage in REPL:
# include("/path/to/script.jl")

noizuy

keywords are usually debanding, bit depth expansion, false contour removal, decontouring

CCL-based stuff only works on banding that stems from heavy compression (i.e. completely flat bands) and falls apart with flat content

Debanders

Knowledge-based

• AdaDeband: https://sci-hub.st/http://dx.doi.org/10.1109/LSP.2020.3024985 (https://github.com/google/bband-adaband - shit code kinda slow and CCL based)
• Baugh: https://sci-hub.st/http://dx.doi.org/10.1145/2668904.2668912 (https://github.com/baughg/debanding - pretty different code from paper and CCL based)
• BEF-BDE: https://ieeexplore.ieee.org/document/9496257 (https://gist.github.com/noizuy/ce2d377a5642b1d9191368abd708b9c4)

noizuy

noizuy

import vapoursynth as vs
core = vs. core
from vstools import join, plane, depth

# b-spline like in bbmod
def bblur(c, w=1, h=None):
    if h is None:
        h = w
    return c.resize.Bicubic(width=w, height=h, filter_param_a=1, filter_param_b=0).resize.Bicubic(width=c.width, height=c.height, filter_param_a=1, filter_param_b=0)

noizuy

# https://www.researchgate.net/publication/343806997_Noise-Aware_and_Light-Weight_VLSI_Design_of_Bilateral_Filter_for_Robust_and_Fast_Image_Denoising_in_Mobile_Systems
using LinearAlgebra, Images, SpecialFunctions

function fs(xi, x, σ_s)
    exp((norm(xi - x) ^ 2) / (-2 * σ_s ^ 2))
end

function fr(xi, x, σ_r)
    exp((norm(xi - x) ^ 2) / (-2 * σ_r ^ 2))
end

noizuy

From 9d7c2b58022b0cee8eae1c1308576fb876b067df Mon Sep 17 00:00:00 2001
From: noizuy <85082087+noizuy@users.noreply.github.com>
Date: Sun, 23 Oct 2022 10:42:52 +0200
Subject: [PATCH] add aq-bias-strength parameter New parameter that controls
 the dark bias strength via multiplication of AQ strength in AQ mode 3.

---
 common/base.c         | 5 +++++
 encoder/ratecontrol.c | 2 +-
 x264.c                | 2 ++

noizuy

diff --git a/common/base.c b/common/base.c
index c249b141..6e2f3bf4 100644
--- a/common/base.c
+++ b/common/base.c
@@ -416,6 +416,7 @@ REALIGN_STACK void x264_param_default( x264_param_t *param )
     param->rc.f_pb_factor = 1.3;
     param->rc.i_aq_mode = X264_AQ_VARIANCE;
     param->rc.f_aq_strength = 1.0;
+    param->rc.f_aq_bias_strength = 1.0;
     param->rc.i_lookahead = 40;

noizuy

diff --git a/src/flash3kyuu_deband_impl_c.cpp b/src/flash3kyuu_deband_impl_c.cpp
index f1e800b..31cd792 100644
--- a/src/flash3kyuu_deband_impl_c.cpp
+++ b/src/flash3kyuu_deband_impl_c.cpp
@@ -167,6 +167,14 @@ static __forceinline void __cdecl process_plane_plainc_mode12_high(const process
                     int diff4 = ref_4_up - src_px_up;
                     use_org_px_as_base = is_above_threshold(threshold, diff1, diff2, diff3, diff4);
                 }
+
+		int ref_pixel_sum = abs(ref_1_up - src_px_up);

noizuy

From 534154762b267f7a8e16620b530de2b18026c5e3 Mon Sep 17 00:00:00 2001
From: noizuy <85082087+noizuy@users.noreply.github.com>
Date: Mon, 26 Sep 2022 12:46:29 +0200
Subject: [PATCH] add AQ fast edge option At high resolutions, AQ modes 4 & 5
 show a significant speed reduction. This option allows the user to omit the
 5x5 Gaussian blur applied before edge detection is performed, slightly
 improving encode speed.

---
 doc/reST/cli.rst             |  4 +++