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Jpeg 12 bit support #784

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merged 8 commits into from
Dec 30, 2018
Merged

Jpeg 12 bit support #784

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5ee5da8
Start work on jpeg 12 bit support
feliwir Dec 6, 2018
ede120d
Work on 12-bit support
feliwir Dec 9, 2018
5ef3f19
Add missing Non-SIMD implementation
feliwir Dec 9, 2018
b17bda5
Fix style issues
feliwir Dec 10, 2018
4636fe6
Fix style issues
feliwir Dec 10, 2018
8cba23f
Merge remote-tracking branch 'upstream/master' into jpeg-12bit
JimBobSquarePants Dec 21, 2018
133c854
Minor optimizations
JimBobSquarePants Dec 21, 2018
537dbcf
Update reference images and decoder
JimBobSquarePants Dec 21, 2018
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16 changes: 8 additions & 8 deletions src/ImageSharp/Common/Tuples/Vector4Pair.cs
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Expand Up @@ -37,21 +37,21 @@ public void AddInplace(ref Vector4Pair other)
this.B += other.B;
}

/// <summary>
/// Downscale method, specific to Jpeg color conversion. Works only if Vector{float}.Count == 4!
/// <summary>. Works only if Ve
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/// Downscale method, specific to Jpeg color conversctor{float}.Count == 4!
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/// TODO: Move it somewhere else.
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal void RoundAndDownscalePreAvx2()
internal void RoundAndDownscalePreAvx2(float downscaleFactor)
{
ref Vector<float> a = ref Unsafe.As<Vector4, Vector<float>>(ref this.A);
a = a.FastRound();

ref Vector<float> b = ref Unsafe.As<Vector4, Vector<float>>(ref this.B);
b = b.FastRound();

// Downscale by 1/255
var scale = new Vector4(1 / 255f);
// Downscale by 1/factor
var scale = new Vector4(1 / downscaleFactor);
this.A *= scale;
this.B *= scale;
}
Expand All @@ -61,14 +61,14 @@ internal void RoundAndDownscalePreAvx2()
/// TODO: Move it somewhere else.
/// </summary>
[MethodImpl(MethodImplOptions.AggressiveInlining)]
internal void RoundAndDownscaleAvx2()
internal void RoundAndDownscaleAvx2(float downscaleFactor)
{
ref Vector<float> self = ref Unsafe.As<Vector4Pair, Vector<float>>(ref this);
Vector<float> v = self;
v = v.FastRound();

// Downscale by 1/255
v *= new Vector<float>(1 / 255f);
// Downscale by 1/factor
v *= new Vector<float>(1 / downscaleFactor);
self = v;
}

Expand Down
19 changes: 10 additions & 9 deletions src/ImageSharp/Formats/Jpeg/Components/Block8x8F.Generated.cs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,7 @@
// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.

using System;
using System.Numerics;
using System.Runtime.CompilerServices;

Expand All @@ -9,10 +10,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
{
internal partial struct Block8x8F
{
private static readonly Vector4 CMin4 = new Vector4(0F);
private static readonly Vector4 CMax4 = new Vector4(255F);
private static readonly Vector4 COff4 = new Vector4(128F);

/// <summary>
/// Transpose the block into the destination block.
/// </summary>
Expand Down Expand Up @@ -94,10 +91,14 @@ public void TransposeInto(ref Block8x8F d)
}

/// <summary>
/// Level shift by +128, clip to [0, 255]
/// Level shift by +maximum/2, clip to [0, maximum]
/// </summary>
public void NormalizeColorsInplace()
public void NormalizeColorsInplace(float maximum)
{
Vector4 CMin4 = new Vector4(0F);
Vector4 CMax4 = new Vector4(maximum);
Vector4 COff4 = new Vector4((float)Math.Ceiling(maximum/2));

this.V0L = Vector4.Clamp(this.V0L + COff4, CMin4, CMax4);
this.V0R = Vector4.Clamp(this.V0R + COff4, CMin4, CMax4);
this.V1L = Vector4.Clamp(this.V1L + COff4, CMin4, CMax4);
Expand All @@ -120,10 +121,10 @@ public void NormalizeColorsInplace()
/// AVX2-only variant for executing <see cref="NormalizeColorsInplace"/> and <see cref="RoundInplace"/> in one step.
/// </summary>
[MethodImpl(InliningOptions.ShortMethod)]
public void NormalizeColorsAndRoundInplaceAvx2()
public void NormalizeColorsAndRoundInplaceAvx2(float maximum)
{
Vector<float> off = new Vector<float>(128f);
Vector<float> max = new Vector<float>(255F);
Vector<float> off = new Vector<float>((float)Math.Ceiling(maximum/2));
Vector<float> max = new Vector<float>(maximum);

ref Vector<float> row0 = ref Unsafe.As<Vector4, Vector<float>>(ref this.V0L);
row0 = NormalizeAndRound(row0, off, max);
Expand Down
19 changes: 10 additions & 9 deletions src/ImageSharp/Formats/Jpeg/Components/Block8x8F.Generated.tt
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Expand Up @@ -11,6 +11,7 @@
// Copyright (c) Six Labors and contributors.
// Licensed under the Apache License, Version 2.0.

using System;
using System.Numerics;
using System.Runtime.CompilerServices;

Expand All @@ -22,10 +23,6 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
{
internal partial struct Block8x8F
{
private static readonly Vector4 CMin4 = new Vector4(0F);
private static readonly Vector4 CMax4 = new Vector4(255F);
private static readonly Vector4 COff4 = new Vector4(128F);

/// <summary>
/// Transpose the block into the destination block.
/// </summary>
Expand Down Expand Up @@ -59,10 +56,14 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
}

/// <summary>
/// Level shift by +128, clip to [0, 255]
/// Level shift by +maximum/2, clip to [0, maximum]
/// </summary>
public void NormalizeColorsInplace()
public void NormalizeColorsInplace(float maximum)
{
Vector4 CMin4 = new Vector4(0F);
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These values are being calculated more than once in the same partial struct.

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What we can do is to refactor the normalization logic into it's own stateful type (preferably a struct), where minimum/maximum/half values are nonstatic members initialized in the constructor.

Vector4 CMax4 = new Vector4(maximum);
Vector4 COff4 = new Vector4((float)Math.Ceiling(maximum/2));

<#

PushIndent(" ");
Expand All @@ -83,10 +84,10 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components
/// AVX2-only variant for executing <see cref="NormalizeColorsInplace"/> and <see cref="RoundInplace"/> in one step.
/// </summary>
[MethodImpl(InliningOptions.ShortMethod)]
public void NormalizeColorsAndRoundInplaceAvx2()
public void NormalizeColorsAndRoundInplaceAvx2(float maximum)
{
Vector<float> off = new Vector<float>(128f);
Vector<float> max = new Vector<float>(255F);
Vector<float> off = new Vector<float>((float)Math.Ceiling(maximum/2));
Vector<float> max = new Vector<float>(maximum);
<#

for (int i = 0; i < 8; i++)
Expand Down
8 changes: 4 additions & 4 deletions src/ImageSharp/Formats/Jpeg/Components/Block8x8F.cs
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Expand Up @@ -467,17 +467,17 @@ public Block8x8 RoundAsInt16Block()
}

/// <summary>
/// Level shift by +128, clip to [0..255], and round all the values in the block.
/// Level shift by +maximum/2, clip to [0..maximum], and round all the values in the block.
/// </summary>
public void NormalizeColorsAndRoundInplace()
public void NormalizeColorsAndRoundInplace(float maximum)
{
if (SimdUtils.IsAvx2CompatibleArchitecture)
{
this.NormalizeColorsAndRoundInplaceAvx2();
this.NormalizeColorsAndRoundInplaceAvx2(maximum);
}
else
{
this.NormalizeColorsInplace();
this.NormalizeColorsInplace(maximum);
this.RoundInplace();
}
}
Expand Down
11 changes: 7 additions & 4 deletions ...ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromCmyk.cs
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Expand Up @@ -10,8 +10,8 @@ internal abstract partial class JpegColorConverter
{
internal class FromCmyk : JpegColorConverter
{
public FromCmyk()
: base(JpegColorSpace.Cmyk)
public FromCmyk(int precision)
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I prefer to have more type safety in the codebase. (-1, 17 and 222 are invalid values for precision ;) ). I suggest an enum having the following form, so you can easily cast it to int when necessary.

enum JpegPrecision
{
   EightBits = 8,
   TwelveBits = 12
}

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Hmmm... Read section 4.7 here. Lossless jpeg supports additional precision so we should bear that in mind when naming our enum. https://www.w3.org/Graphics/JPEG/itu-t81.pdf

For DCT-based processes, two alternative sample precisions are specified: either 8 bits or 12 bits per sample. Applications which use samples with other precisions can use either 8-bit or 12-bit precision by shifting their source image samples appropriately. The baseline process uses only 8-bit precision. DCT-based implementations which handle 12-bit source image samples are likely to need greater computational resources than those which handle only 8-bit source images. Consequently in this Specification separate normative requirements are defined for 8-bit and 12-bit DCT-based processes.

For lossless processes the sample precision is specified to be from 2 to 16 bits

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Oops. The options I see:

  1. Keep the type as is (int), and introduce some DebugGuard checks in the code
  2. Introduce an enum defining all entries for 2-16
  3. Since we do not support lossless jpeg, define only EightBits and TwelveBits for now, and YAGNI out the rest, letting our future selves to find out how to manage the lossless case.

I'm pretty much for option 3.

: base(JpegColorSpace.Cmyk, precision)
{
}

Expand All @@ -25,14 +25,17 @@ public override void ConvertToRgba(in ComponentValues values, Span<Vector4> resu

var v = new Vector4(0, 0, 0, 1F);

var scale = new Vector4(1 / 255F, 1 / 255F, 1 / 255F, 1F);
var scale = new Vector4(1 / this.MaximumValue,
1 / this.MaximumValue,
1 / this.MaximumValue,
1F);

for (int i = 0; i < result.Length; i++)
{
float c = cVals[i];
float m = mVals[i];
float y = yVals[i];
float k = kVals[i] / 255F;
float k = kVals[i] / this.MaximumValue;

v.X = c * k;
v.Y = m * k;
Expand Down
9 changes: 6 additions & 3 deletions ...Sharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromGrayScale.cs
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Expand Up @@ -12,14 +12,17 @@ internal abstract partial class JpegColorConverter
{
internal class FromGrayscale : JpegColorConverter
{
public FromGrayscale()
: base(JpegColorSpace.Grayscale)
public FromGrayscale(int precision)
: base(JpegColorSpace.Grayscale, precision)
{
}

public override void ConvertToRgba(in ComponentValues values, Span<Vector4> result)
{
var scale = new Vector4(1 / 255F, 1 / 255F, 1 / 255F, 1F);
var scale = new Vector4(1 / this.MaximumValue,
1 / this.MaximumValue,
1 / this.MaximumValue,
1F);

ref float sBase = ref MemoryMarshal.GetReference(values.Component0);
ref Vector4 dBase = ref MemoryMarshal.GetReference(result);
Expand Down
9 changes: 6 additions & 3 deletions src/ImageSharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromRgb.cs
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Expand Up @@ -10,8 +10,8 @@ internal abstract partial class JpegColorConverter
{
internal class FromRgb : JpegColorConverter
{
public FromRgb()
: base(JpegColorSpace.RGB)
public FromRgb(int precision)
: base(JpegColorSpace.RGB, precision)
{
}

Expand All @@ -24,7 +24,10 @@ public override void ConvertToRgba(in ComponentValues values, Span<Vector4> resu

var v = new Vector4(0, 0, 0, 1);

var scale = new Vector4(1 / 255F, 1 / 255F, 1 / 255F, 1F);
var scale = new Vector4(1 / this.MaximumValue,
1 / this.MaximumValue,
1 / this.MaximumValue,
1F);

for (int i = 0; i < result.Length; i++)
{
Expand Down
14 changes: 7 additions & 7 deletions ...harp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromYCbCrBasic.cs
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Expand Up @@ -10,17 +10,17 @@ internal abstract partial class JpegColorConverter
{
internal class FromYCbCrBasic : JpegColorConverter
{
public FromYCbCrBasic()
: base(JpegColorSpace.YCbCr)
public FromYCbCrBasic(int precision)
: base(JpegColorSpace.YCbCr, precision)
{
}

public override void ConvertToRgba(in ComponentValues values, Span<Vector4> result)
{
ConvertCore(values, result);
ConvertCore(values, result, this.MaximumValue, this.HalfValue);
}

internal static void ConvertCore(in ComponentValues values, Span<Vector4> result)
internal static void ConvertCore(in ComponentValues values, Span<Vector4> result, float maxValue, float halfValue)
{
// TODO: We can optimize a lot here with Vector<float> and SRCS.Unsafe()!
ReadOnlySpan<float> yVals = values.Component0;
Expand All @@ -29,13 +29,13 @@ internal static void ConvertCore(in ComponentValues values, Span<Vector4> result

var v = new Vector4(0, 0, 0, 1);

var scale = new Vector4(1 / 255F, 1 / 255F, 1 / 255F, 1F);
var scale = new Vector4(1 / maxValue, 1 / maxValue, 1 / maxValue, 1F);

for (int i = 0; i < result.Length; i++)
{
float y = yVals[i];
float cb = cbVals[i] - 128F;
float cr = crVals[i] - 128F;
float cb = cbVals[i] - halfValue;
float cr = crVals[i] - halfValue;

v.X = MathF.Round(y + (1.402F * cr), MidpointRounding.AwayFromZero);
v.Y = MathF.Round(y - (0.344136F * cb) - (0.714136F * cr), MidpointRounding.AwayFromZero);
Expand Down
29 changes: 15 additions & 14 deletions ...Sharp/Formats/Jpeg/Components/Decoder/ColorConverters/JpegColorConverter.FromYCbCrSimd.cs
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Expand Up @@ -14,8 +14,8 @@ internal abstract partial class JpegColorConverter
{
internal class FromYCbCrSimd : JpegColorConverter
{
public FromYCbCrSimd()
: base(JpegColorSpace.YCbCr)
public FromYCbCrSimd(int precision)
: base(JpegColorSpace.YCbCr, precision)
{
}

Expand All @@ -25,16 +25,17 @@ public override void ConvertToRgba(in ComponentValues values, Span<Vector4> resu
int simdCount = result.Length - remainder;
if (simdCount > 0)
{
ConvertCore(values.Slice(0, simdCount), result.Slice(0, simdCount));
ConvertCore(values.Slice(0, simdCount), result.Slice(0, simdCount), this.MaximumValue, this.HalfValue);
}

FromYCbCrBasic.ConvertCore(values.Slice(simdCount, remainder), result.Slice(simdCount, remainder));
FromYCbCrBasic.ConvertCore(values.Slice(simdCount, remainder), result.Slice(simdCount, remainder),
this.MaximumValue, this.HalfValue);
}

/// <summary>
/// SIMD convert using buffers of sizes divisible by 8.
/// </summary>
internal static void ConvertCore(in ComponentValues values, Span<Vector4> result)
internal static void ConvertCore(in ComponentValues values, Span<Vector4> result, float maxValue, float halfValue)
{
DebugGuard.IsTrue(result.Length % 8 == 0, nameof(result), "result.Length should be divisible by 8!");

Expand All @@ -48,7 +49,7 @@ internal static void ConvertCore(in ComponentValues values, Span<Vector4> result
ref Vector4Octet resultBase =
ref Unsafe.As<Vector4, Vector4Octet>(ref MemoryMarshal.GetReference(result));

var chromaOffset = new Vector4(-128f);
var chromaOffset = new Vector4(-halfValue);

// Walking 8 elements at one step:
int n = result.Length / 8;
Expand All @@ -58,11 +59,11 @@ internal static void ConvertCore(in ComponentValues values, Span<Vector4> result
// y = yVals[i];
Vector4Pair y = Unsafe.Add(ref yBase, i);

// cb = cbVals[i] - 128F;
// cb = cbVals[i] - halfValue);
Vector4Pair cb = Unsafe.Add(ref cbBase, i);
cb.AddInplace(chromaOffset);

// cr = crVals[i] - 128F;
// cr = crVals[i] - halfValue;
Vector4Pair cr = Unsafe.Add(ref crBase, i);
cr.AddInplace(chromaOffset);

Expand Down Expand Up @@ -90,15 +91,15 @@ internal static void ConvertCore(in ComponentValues values, Span<Vector4> result
if (Vector<float>.Count == 4)
{
// TODO: Find a way to properly run & test this path on AVX2 PC-s! (Have I already mentioned that Vector<T> is terrible?)
r.RoundAndDownscalePreAvx2();
g.RoundAndDownscalePreAvx2();
b.RoundAndDownscalePreAvx2();
r.RoundAndDownscalePreAvx2(maxValue);
g.RoundAndDownscalePreAvx2(maxValue);
b.RoundAndDownscalePreAvx2(maxValue);
}
else if (SimdUtils.IsAvx2CompatibleArchitecture)
{
r.RoundAndDownscaleAvx2();
g.RoundAndDownscaleAvx2();
b.RoundAndDownscaleAvx2();
r.RoundAndDownscaleAvx2(maxValue);
g.RoundAndDownscaleAvx2(maxValue);
b.RoundAndDownscaleAvx2(maxValue);
}
else
{
Expand Down
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