ref: 5715c39cf80f400f68132b0e9d0b33dc21016cbf
dir: /vp8/encoder/denoising.c/
/*
* Copyright (c) 2012 The WebM project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "denoising.h"
#include "vp8/common/reconinter.h"
#include "vpx/vpx_integer.h"
#include "vpx_mem/vpx_mem.h"
#include "vpx_rtcd.h"
static const unsigned int NOISE_MOTION_THRESHOLD = 20 * 20;
// SSE_DIFF_THRESHOLD is selected as ~95% confidence assuming var(noise) ~= 100.
static const unsigned int SSE_DIFF_THRESHOLD = 16 * 16 * 20;
static const unsigned int SSE_THRESHOLD = 16 * 16 * 40;
static unsigned int denoiser_motion_compensate(YV12_BUFFER_CONFIG *src,
YV12_BUFFER_CONFIG *dst,
MACROBLOCK *x,
unsigned int best_sse,
unsigned int zero_mv_sse,
int recon_yoffset,
int recon_uvoffset)
{
MACROBLOCKD filter_xd = x->e_mbd;
int mv_col;
int mv_row;
int sse_diff = zero_mv_sse - best_sse;
// Compensate the running average.
filter_xd.pre.y_buffer = src->y_buffer + recon_yoffset;
filter_xd.pre.u_buffer = src->u_buffer + recon_uvoffset;
filter_xd.pre.v_buffer = src->v_buffer + recon_uvoffset;
// Write the compensated running average to the destination buffer.
filter_xd.dst.y_buffer = dst->y_buffer + recon_yoffset;
filter_xd.dst.u_buffer = dst->u_buffer + recon_uvoffset;
filter_xd.dst.v_buffer = dst->v_buffer + recon_uvoffset;
// Use the best MV for the compensation.
filter_xd.mode_info_context->mbmi.ref_frame = LAST_FRAME;
filter_xd.mode_info_context->mbmi.mode = filter_xd.best_sse_inter_mode;
filter_xd.mode_info_context->mbmi.mv = filter_xd.best_sse_mv;
filter_xd.mode_info_context->mbmi.need_to_clamp_mvs =
filter_xd.need_to_clamp_best_mvs;
mv_col = filter_xd.best_sse_mv.as_mv.col;
mv_row = filter_xd.best_sse_mv.as_mv.row;
if (filter_xd.mode_info_context->mbmi.mode <= B_PRED ||
(mv_row *mv_row + mv_col *mv_col <= NOISE_MOTION_THRESHOLD &&
sse_diff < SSE_DIFF_THRESHOLD))
{
// Handle intra blocks as referring to last frame with zero motion and
// let the absolute pixel difference affect the filter factor.
// Also consider small amount of motion as being random walk due to
// noise, if it doesn't mean that we get a much bigger error.
// Note that any changes to the mode info only affects the denoising.
filter_xd.mode_info_context->mbmi.ref_frame = LAST_FRAME;
filter_xd.mode_info_context->mbmi.mode = ZEROMV;
filter_xd.mode_info_context->mbmi.mv.as_int = 0;
x->e_mbd.best_sse_inter_mode = ZEROMV;
x->e_mbd.best_sse_mv.as_int = 0;
best_sse = zero_mv_sse;
}
if (!x->skip)
{
vp8_build_inter_predictors_mb(&filter_xd);
}
else
{
vp8_build_inter16x16_predictors_mb(&filter_xd,
filter_xd.dst.y_buffer,
filter_xd.dst.u_buffer,
filter_xd.dst.v_buffer,
filter_xd.dst.y_stride,
filter_xd.dst.uv_stride);
}
return best_sse;
}
// The filtering coefficients used for denoizing are adjusted for static
// blocks, or blocks with very small motion vectors. This is done through
// the motion magnitude parameter.
//
// There are currently 2048 possible mapping from absolute difference to
// filter coefficient depending on the motion magnitude. Each mapping is
// in a LUT table. All these tables are staticly allocated but they are only
// filled on their first use.
//
// Each entry is a pair of 16b values, the coefficient and its complement
// to 256. Each of these value should only be 8b but they are 16b wide to
// avoid slow partial register manipulations.
enum {num_motion_magnitude_adjustments = 2048};
static union coeff_pair filter_coeff_LUT[num_motion_magnitude_adjustments][256];
static uint8_t filter_coeff_LUT_initialized[num_motion_magnitude_adjustments] =
{ 0 };
union coeff_pair *vp8_get_filter_coeff_LUT(unsigned int motion_magnitude)
{
union coeff_pair *LUT;
unsigned int motion_magnitude_adjustment = motion_magnitude >> 3;
if (motion_magnitude_adjustment >= num_motion_magnitude_adjustments)
{
motion_magnitude_adjustment = num_motion_magnitude_adjustments - 1;
}
LUT = filter_coeff_LUT[motion_magnitude_adjustment];
if (!filter_coeff_LUT_initialized[motion_magnitude_adjustment])
{
int absdiff;
for (absdiff = 0; absdiff < 256; ++absdiff)
{
unsigned int filter_coefficient;
filter_coefficient = (255 << 8) / (256 + ((absdiff * 330) >> 3));
filter_coefficient += filter_coefficient /
(3 + motion_magnitude_adjustment);
if (filter_coefficient > 255)
{
filter_coefficient = 255;
}
LUT[absdiff].as_short[0] = filter_coefficient ;
LUT[absdiff].as_short[1] = 256 - filter_coefficient;
}
filter_coeff_LUT_initialized[motion_magnitude_adjustment] = 1;
}
return LUT;
}
void vp8_denoiser_filter_c(YV12_BUFFER_CONFIG *mc_running_avg,
YV12_BUFFER_CONFIG *running_avg, MACROBLOCK *signal,
unsigned int motion_magnitude, int y_offset,
int uv_offset)
{
unsigned char *sig = signal->thismb;
int sig_stride = 16;
unsigned char *mc_running_avg_y = mc_running_avg->y_buffer + y_offset;
int mc_avg_y_stride = mc_running_avg->y_stride;
unsigned char *running_avg_y = running_avg->y_buffer + y_offset;
int avg_y_stride = running_avg->y_stride;
const union coeff_pair *LUT = vp8_get_filter_coeff_LUT(motion_magnitude);
int r, c;
for (r = 0; r < 16; ++r)
{
// Calculate absolute differences
unsigned char abs_diff[16];
union coeff_pair filter_coefficient[16];
for (c = 0; c < 16; ++c)
{
int absdiff = sig[c] - mc_running_avg_y[c];
absdiff = absdiff > 0 ? absdiff : -absdiff;
abs_diff[c] = absdiff;
}
// Use LUT to get filter coefficients (two 16b value; f and 256-f)
for (c = 0; c < 16; ++c)
{
filter_coefficient[c] = LUT[abs_diff[c]];
}
// Filtering...
for (c = 0; c < 16; ++c)
{
const uint16_t state = (uint16_t)(mc_running_avg_y[c]);
const uint16_t sample = (uint16_t)(sig[c]);
running_avg_y[c] = (filter_coefficient[c].as_short[0] * state +
filter_coefficient[c].as_short[1] * sample + 128) >> 8;
}
// Depending on the magnitude of the difference between the signal and
// filtered version, either replace the signal by the filtered one or
// update the filter state with the signal when the change in a pixel
// isn't classified as noise.
for (c = 0; c < 16; ++c)
{
const int diff = sig[c] - running_avg_y[c];
if (diff * diff < NOISE_DIFF2_THRESHOLD)
{
sig[c] = running_avg_y[c];
}
else
{
running_avg_y[c] = sig[c];
}
}
// Update pointers for next iteration.
sig += sig_stride;
mc_running_avg_y += mc_avg_y_stride;
running_avg_y += avg_y_stride;
}
}
int vp8_denoiser_allocate(VP8_DENOISER *denoiser, int width, int height)
{
assert(denoiser);
denoiser->yv12_running_avg.flags = 0;
if (vp8_yv12_alloc_frame_buffer(&(denoiser->yv12_running_avg), width,
height, VP8BORDERINPIXELS) < 0)
{
vp8_denoiser_free(denoiser);
return 1;
}
denoiser->yv12_mc_running_avg.flags = 0;
if (vp8_yv12_alloc_frame_buffer(&(denoiser->yv12_mc_running_avg), width,
height, VP8BORDERINPIXELS) < 0)
{
vp8_denoiser_free(denoiser);
return 1;
}
vpx_memset(denoiser->yv12_running_avg.buffer_alloc, 0,
denoiser->yv12_running_avg.frame_size);
vpx_memset(denoiser->yv12_mc_running_avg.buffer_alloc, 0,
denoiser->yv12_mc_running_avg.frame_size);
return 0;
}
void vp8_denoiser_free(VP8_DENOISER *denoiser)
{
assert(denoiser);
vp8_yv12_de_alloc_frame_buffer(&denoiser->yv12_running_avg);
vp8_yv12_de_alloc_frame_buffer(&denoiser->yv12_mc_running_avg);
}
void vp8_denoiser_denoise_mb(VP8_DENOISER *denoiser,
MACROBLOCK *x,
unsigned int best_sse,
unsigned int zero_mv_sse,
int recon_yoffset,
int recon_uvoffset)
{
int mv_row;
int mv_col;
unsigned int motion_magnitude2;
// Motion compensate the running average.
best_sse = denoiser_motion_compensate(&denoiser->yv12_running_avg,
&denoiser->yv12_mc_running_avg,
x,
best_sse,
zero_mv_sse,
recon_yoffset,
recon_uvoffset);
mv_row = x->e_mbd.best_sse_mv.as_mv.row;
mv_col = x->e_mbd.best_sse_mv.as_mv.col;
motion_magnitude2 = mv_row * mv_row + mv_col * mv_col;
if (best_sse > SSE_THRESHOLD ||
motion_magnitude2 > 8 * NOISE_MOTION_THRESHOLD)
{
// No filtering of this block since it differs too much from the
// predictor, or the motion vector magnitude is considered too big.
vp8_copy_mem16x16(x->thismb, 16,
denoiser->yv12_running_avg.y_buffer + recon_yoffset,
denoiser->yv12_running_avg.y_stride);
return;
}
// Filter.
vp8_denoiser_filter(&denoiser->yv12_mc_running_avg,
&denoiser->yv12_running_avg, x, motion_magnitude2,
recon_yoffset, recon_uvoffset);
}