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Update metric for upstream changes
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@shssoichiro
shssoichiro committed Apr 20, 2023
1 parent 2117006 commit b1515ff
Showing 4 changed files with 185 additions and 123 deletions.
4 changes: 4 additions & 0 deletions CHANGELOG.md
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@@ -1,3 +1,7 @@
## Version 0.4.0

- Update to [version 2.1 of the metric](https://github.com/cloudinary/ssimulacra2/compare/v2.0...v2.1)

## Version 0.3.1

- Minor optimizations
2 changes: 1 addition & 1 deletion Cargo.toml
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@@ -1,6 +1,6 @@
[package]
name = "ssimulacra2"
version = "0.3.1"
version = "0.4.0"
edition = "2021"
rust-version = "1.61.0"
description = "Rust implementation of the SSIMULACRA2 metric"
2 changes: 1 addition & 1 deletion README.md
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@@ -4,4 +4,4 @@
[![Crates.io](https://img.shields.io/crates/v/ssimulacra2?style=for-the-badge)](https://crates.io/crates/ssimulacra2)
[![LICENSE](https://img.shields.io/crates/l/ssimulacra2?style=for-the-badge)](https://github.com/rust-av/ssimulacra2/blob/main/LICENSE)

Rust implementation of the SSIMULACRA2 metric.
Rust implementation of the [SSIMULACRA2 metric](https://github.com/cloudinary/ssimulacra2).
300 changes: 179 additions & 121 deletions src/lib.rs
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@@ -135,11 +135,22 @@ pub fn compute_frame_ssimulacra2<T: TryInto<LinearRgb>, U: TryInto<LinearRgb>>(
Ok(msssim.score())
}

// Get all components in more or less 0..1 range
// Range of Rec2020 with these adjustments:
// X: 0.017223..0.998838
// Y: 0.010000..0.855303
// B: 0.048759..0.989551
// Range of sRGB:
// X: 0.204594..0.813402
// Y: 0.010000..0.855308
// B: 0.272295..0.938012
// The maximum pixel-wise difference has to be <= 1 for the ssim formula to make
// sense.
fn make_positive_xyb(xyb: &mut Xyb) {
for pix in xyb.data_mut().iter_mut() {
pix[2] += 1.1f32 - pix[1];
pix[0] += 0.5f32;
pix[1] += 0.05f32;
pix[2] = (pix[2] - pix[1]) + 0.55;
pix[0] = (pix[0]).mul_add(14.0, 0.42);
pix[1] += 0.01;
}
}

@@ -233,9 +244,22 @@ fn ssim_map(
let mu22 = mu2 * mu2;
let mu12 = mu1 * mu2;
let mu_diff = mu1 - mu2;

// Correction applied compared to the original SSIM formula, which has:
// luma_err = 2 * mu1 * mu2 / (mu1^2 + mu2^2)
// = 1 - (mu1 - mu2)^2 / (mu1^2 + mu2^2)
// The denominator causes error in the darks (low mu1 and mu2) to weigh
// more than error in the brights (high mu1 and mu2). This would make
// sense if values correspond to linear luma. However, the actual values
// are either gamma-compressed luma (which supposedly is already
// perceptually uniform) or chroma (where weighing green more than red
// or blue more than yellow does not make any sense at all). So it is
// better to simply drop this denominator.
let num_m = mu_diff.mul_add(-mu_diff, 1.0f32);
let num_s = 2f32.mul_add(row_s12[x] - mu12, C2);
let denom_s = (row_s11[x] - mu11) + (row_s22[x] - mu22) + C2;
// Use 1 - SSIM' so it becomes an error score instead of a quality
// index. This makes it make sense to compute an L_4 norm.
let mut d = 1.0f64 - f64::from((num_m * num_s) / denom_s);
d = d.max(0.0);
sum1[0] += d;
@@ -271,13 +295,15 @@ fn edge_diff_map(
let d1: f64 = (1.0 + f64::from((row2[x] - rowm2[x]).abs()))
/ (1.0 + f64::from((row1[x] - rowm1[x]).abs()))
- 1.0;

// d1 > 0: distorted has an edge where original is smooth
// (indicating ringing, color banding, blockiness, etc)
// d1 < 0: original has an edge where distorted is smooth
// (indicating smoothing, blurring, smearing, etc)
let artifact = d1.max(0.0);
sum1[0] += artifact;
sum1[1] += artifact.powi(4);

// d1 < 0: original has an edge where distorted is smooth
// (indicating smoothing, blurring, smearing, etc)
let detail_lost = (-d1).max(0.0);
sum1[2] += detail_lost;
sum1[3] += detail_lost.powi(4);
@@ -304,117 +330,147 @@ struct MsssimScale {
}

impl Msssim {
// The final score is based on a weighted sum of 108 sub-scores:
// - for 6 scales (1:1 to 1:32)
// - for 6 scales (1:1 to 1:32, downsampled in linear RGB)
// - for 3 components (X + 0.5, Y, B - Y + 1.0)
// - for 3 components (X, Y, B-Y, rescaled to 0..1 range)
// - using 2 norms (the 1-norm and the 4-norm)
// - using 2 norms (the 1-norm and the 4-norm)
// - over 3 error maps:
// - over 3 error maps:
// - SSIM
// - SSIM' (SSIM without the spurious gamma correction term)
// - "ringing" (distorted edges where there are no orig edges)
// - "ringing" (distorted edges where there are no orig edges)
// - "blurring" (orig edges where there are no distorted edges)
// - "blurring" (orig edges where there are no distorted edges)
// The weights were obtained by running Nelder-Mead simplex search,
// The weights were obtained by running Nelder-Mead simplex search,
// optimizing to minimize MSE and maximize Kendall and Pearson correlation
// optimizing to minimize MSE for the CID22 training set and to
// for training data consisting of 17611 subjective quality scores,
// maximize Kendall rank correlation (and with a lower weight,
// validated on separate validation data consisting of 4292 scores.
// also Pearson correlation) with the CID22 training set and the
// TID2013, Kadid10k and KonFiG-IQA datasets.
// Validation was done on the CID22 validation set.
// Final results after tuning (Kendall | Spearman | Pearson):
// CID22: 0.6903 | 0.8805 | 0.8583
// TID2013: 0.6590 | 0.8445 | 0.8471
// KADID-10k: 0.6175 | 0.8133 | 0.8030
// KonFiG(F): 0.7668 | 0.9194 | 0.9136
#[allow(clippy::too_many_lines)]
pub fn score(&self) -> f64 {
const WEIGHT: [f64; 108] = [
0.0_f64,
0.0_f64,
0.0_f64,
1.003_547_935_251_235_3_f64,
0.000_113_220_611_104_747_35_f64,
0.000_404_429_918_236_859_36_f64,
0.001_895_383_410_578_377_3_f64,
0.0_f64,
0.0_f64,
8.982_542_997_575_905_f64,
0.989_978_579_604_555_6_f64,
0.0_f64,
0.974_831_513_120_794_2_f64,
0.958_157_516_993_797_3_f64,
0.0_f64,
0.513_361_177_795_294_6_f64,
1.042_318_931_733_124_3_f64,
0.000_308_010_928_520_841_f64,
12.149_584_966_240_063_f64,
0.956_557_724_811_546_7_f64,
0.0_f64,
1.040_666_812_313_682_4_f64,
81.511_390_460_573_62_f64,
0.305_933_918_953_309_46_f64,
1.075_221_443_362_677_9_f64,
1.103_904_236_946_461_1_f64,
0.0_f64,
1.021_911_638_819_618_f64,
1.114_182_329_685_572_2_f64,
0.973_084_575_144_170_5_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.983_391_842_609_550_5_f64,
0.792_038_513_705_986_7_f64,
0.971_074_041_151_405_3_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.538_707_790_315_263_8_f64,
0.0_f64,
3.403_694_560_115_580_4_f64,
0.0_f64,
0.0_f64,
0.0_f64,
2.337_569_295_661_117_f64,
0.0_f64,
5.707_946_510_901_609_f64,
37.830_864_238_781_57_f64,
0.0_f64,
0.0_f64,
3.825_820_059_430_518_5_f64,
0.0_f64,
0.0_f64,
24.073_659_674_271_497_f64,
0.0_f64,
0.0_f64,
13.181_871_265_286_068_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
10.007_501_212_628_95_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
52.514_283_856_038_91_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.0_f64,
0.994_646_426_789_441_7_f64,
0.0_f64,
0.0_f64,
0.000_604_044_771_593_481_6_f64,
0.0_f64,
0.0_f64,
0.994_517_149_137_407_2_f64,
0.0_f64,
2.826_004_380_945_437_6_f64,
1.005_264_276_653_451_6_f64,
8.201_441_997_546_244e-5_f64,
12.154_041_855_876_695_f64,
32.292_928_706_201_266_f64,
0.992_837_130_387_521_f64,
0.0_f64,
30.719_255_178_446_03_f64,
0.000_123_099_070_222_787_43_f64,
0.0_f64,
0.982_626_023_705_173_4_f64,
0.0_f64,
0.0_f64,
0.998_092_836_783_765_1_f64,
0.012_142_430_067_163_312_f64,
0.0,
0.000_737_660_670_740_658_6,
0.0,
0.0,
0.000_779_348_168_286_730_9,
0.0,
0.0,
0.000_437_115_573_010_737_9,
0.0,
1.104_172_642_665_734_6,
0.000_662_848_341_292_71,
0.000_152_316_327_837_187_52,
0.0,
0.001_640_643_745_659_975_4,
0.0,
1.842_245_552_053_929_8,
11.441_172_603_757_666,
0.0,
0.000_798_910_943_601_516_3,
0.000_176_816_438_078_653,
0.0,
1.878_759_497_954_638_7,
10.949_069_906_051_42,
0.0,
0.000_728_934_699_150_807_2,
0.967_793_708_062_683_3,
0.0,
0.000_140_034_242_854_358_84,
0.998_176_697_785_496_7,
0.000_319_497_559_344_350_53,
0.000_455_099_211_379_206_3,
0.0,
0.0,
0.001_364_876_616_324_339_8,
0.0,
0.0,
0.0,
0.0,
0.0,
7.466_890_328_078_848,
0.0,
17.445_833_984_131_262,
0.000_623_560_163_404_146_6,
0.0,
0.0,
6.683_678_146_179_332,
0.000_377_244_079_796_112_96,
1.027_889_937_768_264,
225.205_153_008_492_74,
0.0,
0.0,
19.213_238_186_143_016,
0.001_140_152_458_661_836_1,
0.001_237_755_635_509_985,
176.393_175_984_506_94,
0.0,
0.0,
24.433_009_998_704_76,
0.285_208_026_121_177_57,
0.000_448_543_692_383_340_8,
0.0,
0.0,
0.0,
34.779_063_444_837_72,
44.835_625_328_877_896,
0.0,
0.0,
0.0,
0.0,
0.0,
0.0,
0.0,
0.0,
0.000_868_055_657_329_169_8,
0.0,
0.0,
0.0,
0.0,
0.0,
0.000_531_319_187_435_874_7,
0.0,
0.000_165_338_141_613_791_12,
0.0,
0.0,
0.0,
0.0,
0.0,
0.000_417_917_180_325_133_6,
0.001_729_082_823_472_283_3,
0.0,
0.002_082_700_584_663_643_7,
0.0,
0.0,
8.826_982_764_996_862,
23.192_433_439_989_26,
0.0,
95.108_049_881_108_6,
0.986_397_803_440_068_2,
0.983_438_279_246_535_3,
0.001_228_640_504_827_849_3,
171.266_725_589_730_7,
0.980_785_887_243_537_9,
0.0,
0.0,
0.0,
0.000_513_006_458_899_067_9,
0.0,
0.000_108_540_578_584_115_37,
];

let mut ssim = 0.0f64;
@@ -433,11 +489,15 @@ impl Msssim {
}
}

ssim = ssim.mul_add(17.829_717_797_575_952_f64, -1.634_169_143_917_183_f64);
ssim *= 0.956_238_261_683_484_4_f64;
ssim = (6.248_496_625_763_138e-5 * ssim * ssim).mul_add(
ssim,
2.326_765_642_916_932f64.mul_add(ssim, -0.020_884_521_182_843_837 * ssim * ssim),
);

if ssim > 0.0f64 {
ssim = ssim
.powf(0.545_326_100_951_021_3_f64)
.powf(0.627_633_646_783_138_7)
.mul_add(-10.0f64, 100.0f64);
} else {
ssim = 100.0f64;
@@ -457,13 +517,13 @@ mod tests {
#[test]
fn test_ssimulacra2() {
let source = image::open(
&PathBuf::from(env!("CARGO_MANIFEST_DIR"))
PathBuf::from(env!("CARGO_MANIFEST_DIR"))
.join("test_data")
.join("tank_source.png"),
)
.unwrap();
let distorted = image::open(
&PathBuf::from(env!("CARGO_MANIFEST_DIR"))
PathBuf::from(env!("CARGO_MANIFEST_DIR"))
.join("test_data")
.join("tank_distorted.png"),
)
@@ -501,14 +561,12 @@ mod tests {
)
.unwrap();
let result = compute_frame_ssimulacra2(source_data, distorted_data).unwrap();
let expected = 8.764_571_f64;
let expected = 17.398_505_f64;
assert!(
// SOMETHING is WEIRD with Github CI where it gives different results across DIFFERENT
// RUNS
(result - expected).abs() < 0.25f64,
"Result {:.6} not equal to expected {:.6}",
result,
expected
"Result {result:.6} not equal to expected {expected:.6}",
);
}
}

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