new segmentation algorithm

fixes the 'blocky sky problem' (saturation problem: when luma was flat,
chroma noise was taking over, resulting in random segment id assigned.
When just using a common uniform segment was better).

+ side clean-up and readibility/experimentability MACRO'ization
+ added '-map 7' option

Change-Id: I35982a9e43c0fecbfdd7b05e4813e8ba8c121d71
This commit is contained in:
skal
2012-09-03 19:40:52 +02:00
parent 2cf1f81590
commit 5725cabac0
6 changed files with 135 additions and 95 deletions

View File

@@ -17,31 +17,18 @@
extern "C" {
#endif
static WEBP_INLINE uint8_t clip_8b(int v) {
return (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
}
static WEBP_INLINE int clip_max(int v, int max) {
return (v > max) ? max : v;
}
//------------------------------------------------------------------------------
// Compute susceptibility based on DCT-coeff histograms:
// the higher, the "easier" the macroblock is to compress.
static int ClipAlpha(int alpha) {
return alpha < 0 ? 0 : alpha > 255 ? 255 : alpha;
}
int VP8GetAlpha(const int histo[MAX_COEFF_THRESH + 1]) {
int num = 0, den = 0, val = 0;
int k;
int alpha;
// note: changing this loop to avoid the numerous "k + 1" slows things down.
for (k = 0; k < MAX_COEFF_THRESH; ++k) {
if (histo[k + 1]) {
val += histo[k + 1];
num += val * (k + 1);
den += (k + 1) * (k + 1);
}
}
// we scale the value to a usable [0..255] range
alpha = den ? 10 * num / den - 5 : 0;
return ClipAlpha(alpha);
}
const int VP8DspScan[16 + 4 + 4] = {
// Luma
0 + 0 * BPS, 4 + 0 * BPS, 8 + 0 * BPS, 12 + 0 * BPS,
@@ -53,27 +40,23 @@ const int VP8DspScan[16 + 4 + 4] = {
8 + 0 * BPS, 12 + 0 * BPS, 8 + 4 * BPS, 12 + 4 * BPS // V
};
static int CollectHistogram(const uint8_t* ref, const uint8_t* pred,
int start_block, int end_block) {
int histo[MAX_COEFF_THRESH + 1] = { 0 };
int16_t out[16];
int j, k;
static void CollectHistogram(const uint8_t* ref, const uint8_t* pred,
int start_block, int end_block,
VP8Histogram* const histo) {
int j;
for (j = start_block; j < end_block; ++j) {
int k;
int16_t out[16];
VP8FTransform(ref + VP8DspScan[j], pred + VP8DspScan[j], out);
// Convert coefficients to bin (within out[]).
// Convert coefficients to bin.
for (k = 0; k < 16; ++k) {
const int v = abs(out[k]) >> 2;
out[k] = (v > MAX_COEFF_THRESH) ? MAX_COEFF_THRESH : v;
}
// Use bin to update histogram.
for (k = 0; k < 16; ++k) {
histo[out[k]]++;
const int v = abs(out[k]) >> 3; // TODO(skal): add rounding?
const int clipped_value = clip_max(v, MAX_COEFF_THRESH);
histo->distribution[clipped_value]++;
}
}
return VP8GetAlpha(histo);
}
//------------------------------------------------------------------------------
@@ -89,15 +72,12 @@ static void InitTables(void) {
if (!tables_ok) {
int i;
for (i = -255; i <= 255 + 255; ++i) {
clip1[255 + i] = (i < 0) ? 0 : (i > 255) ? 255 : i;
clip1[255 + i] = clip_8b(i);
}
tables_ok = 1;
}
}
static WEBP_INLINE uint8_t clip_8b(int v) {
return (!(v & ~0xff)) ? v : v < 0 ? 0 : 255;
}
//------------------------------------------------------------------------------
// Transforms (Paragraph 14.4)