tsai
/
ImageSharp
mirror of https://github.com/SixLabors/ImageSharp
1
0
Fork 0
Code Issues Projects Releases Wiki Activity
Browse Source

Simplify YCbCr

pull/20/head
James Jackson-South 9 years ago
parent
27c3c93cbf
commit
f63e9fe681
2 changed files with 52 additions and 59 deletions
Whitespace
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Split View
Diff Options
Show Stats Download Patch File Download Diff File
  1. 75
      src/ImageSharp/Colors/Colorspaces/YCbCr.cs
  2. 36
      tests/ImageSharp.Tests/Colors/ColorConversionTests.cs

75
src/ImageSharp/Colors/Colorspaces/YCbCr.cs
View File

@ -7,59 +7,49 @@ namespace ImageSharp
{
using System;
using System.ComponentModel;
using System.Numerics;
/// <summary>
/// Represents an YCbCr (luminance, blue chroma, red chroma) color conforming to the
/// Full range standard used in digital imaging systems.
/// Represents an YCbCr (luminance, blue chroma, red chroma) color conforming to the full range standard used in digital imaging systems.
/// <see href="http://en.wikipedia.org/wiki/YCbCr"/>
/// </summary>
public struct YCbCr : IEquatable<YCbCr>, IAlmostEquatable<YCbCr, float>
public struct YCbCr : IEquatable<YCbCr>
{
/// <summary>
/// Represents a <see cref="YCbCr"/> that has Y, Cb, and Cr values set to zero.
/// </summary>
public static readonly YCbCr Empty = default(YCbCr);
/// <summary>
/// The epsilon for comparing floating point numbers.
/// </summary>
private const float Epsilon = 0.001F;
/// <summary>
/// The backing vector for SIMD support.
/// </summary>
private Vector3 backingVector;
/// <summary>
/// Initializes a new instance of the <see cref="YCbCr"/> struct.
/// </summary>
/// <param name="y">The y luminance component.</param>
/// <param name="cb">The cb chroma component.</param>
/// <param name="cr">The cr chroma component.</param>
public YCbCr(float y, float cb, float cr)
public YCbCr(byte y, byte cb, byte cr)
: this()
{
this.backingVector = Vector3.Clamp(new Vector3(y, cb, cr), Vector3.Zero, new Vector3(255));
this.Y = y;
this.Cb = cb;
this.Cr = cr;
}
/// <summary>
/// Gets the Y luminance component.
/// <remarks>A value ranging between 0 and 255.</remarks>
/// </summary>
public float Y => this.backingVector.X;
public byte Y { get; }
/// <summary>
/// Gets the Cb chroma component.
/// <remarks>A value ranging between 0 and 255.</remarks>
/// </summary>
public float Cb => this.backingVector.Y;
public byte Cb { get; }
/// <summary>
/// Gets the Cr chroma component.
/// <remarks>A value ranging between 0 and 255.</remarks>
/// </summary>
public float Cr => this.backingVector.Z;
public byte Cr { get; }
/// <summary>
/// Gets a value indicating whether this <see cref="YCbCr"/> is empty.
@ -79,13 +69,13 @@ namespace ImageSharp
/// </returns>
public static implicit operator YCbCr(Color color)
{
float r = color.R;
float g = color.G;
float b = color.B;
byte r = color.R;
byte g = color.G;
byte b = color.B;
float y = (float)((0.299 * r) + (0.587 * g) + (0.114 * b));
float cb = 128 + (float)((-0.168736 * r) - (0.331264 * g) + (0.5 * b));
float cr = 128 + (float)((0.5 * r) - (0.418688 * g) - (0.081312 * b));
byte y = (byte)((0.299F * r) + (0.587F * g) + (0.114F * b));
byte cb = (byte)(128 + ((-0.168736F * r) - (0.331264F * g) + (0.5F * b)));
byte cr = (byte)(128 + ((0.5F * r) - (0.418688F * g) - (0.081312F * b)));
return new YCbCr(y, cb, cr);
}
@ -127,7 +117,13 @@ namespace ImageSharp
/// <inheritdoc/>
public override int GetHashCode()
{
return GetHashCode(this);
unchecked
{
int hashCode = this.Y.GetHashCode();
hashCode = (hashCode * 397) ^ this.Cb.GetHashCode();
hashCode = (hashCode * 397) ^ this.Cr.GetHashCode();
return hashCode;
}
}
/// <inheritdoc/>
@ -138,7 +134,7 @@ namespace ImageSharp
return "YCbCr [ Empty ]";
}
return $"YCbCr [ Y={this.Y:#0.##}, Cb={this.Cb:#0.##}, Cr={this.Cr:#0.##} ]";
return $"YCbCr [ Y={this.Y}, Cb={this.Cb}, Cr={this.Cr} ]";
}
/// <inheritdoc/>
@ -155,28 +151,7 @@ namespace ImageSharp
/// <inheritdoc/>
public bool Equals(YCbCr other)
{
return this.AlmostEquals(other, Epsilon);
}
/// <inheritdoc/>
public bool AlmostEquals(YCbCr other, float precision)
{
Vector3 result = Vector3.Abs(this.backingVector - other.backingVector);
return result.X < precision
&& result.Y < precision
&& result.Z < precision;
return this.Y == other.Y && this.Cb == other.Cb && this.Cr == other.Cr;
}
/// <summary>
/// Returns the hash code for this instance.
/// </summary>
/// <param name="color">
/// The instance of <see cref="YCbCr"/> to return the hash code for.
/// </param>
/// <returns>
/// A 32-bit signed integer that is the hash code for this instance.
/// </returns>
private static int GetHashCode(YCbCr color) => color.backingVector.GetHashCode();
}
}
}

36
tests/ImageSharp.Tests/Colors/ColorConversionTests.cs
View File

@ -31,23 +31,41 @@ namespace ImageSharp.Tests
Color color = Color.White;
YCbCr yCbCr = color;
Assert.Equal(255, yCbCr.Y, 0);
Assert.Equal(128, yCbCr.Cb, 0);
Assert.Equal(128, yCbCr.Cr, 0);
Assert.Equal(255, yCbCr.Y);
Assert.Equal(128, yCbCr.Cb);
Assert.Equal(128, yCbCr.Cr);
// Black
Color color2 = Color.Black;
YCbCr yCbCr2 = color2;
Assert.Equal(0, yCbCr2.Y, 0);
Assert.Equal(128, yCbCr2.Cb, 0);
Assert.Equal(128, yCbCr2.Cr, 0);
Assert.Equal(0, yCbCr2.Y);
Assert.Equal(128, yCbCr2.Cb);
Assert.Equal(128, yCbCr2.Cr);
// Gray
Color color3 = Color.Gray;
YCbCr yCbCr3 = color3;
Assert.Equal(128, yCbCr3.Y, 0);
Assert.Equal(128, yCbCr3.Cb, 0);
Assert.Equal(128, yCbCr3.Cr, 0);
Assert.Equal(128, yCbCr3.Y);
Assert.Equal(128, yCbCr3.Cb);
Assert.Equal(128, yCbCr3.Cr);
//Assert.Equal(255, yCbCr.Y, 0);
//Assert.Equal(128, yCbCr.Cb, 0);
//Assert.Equal(128, yCbCr.Cr, 0);
//// Black
//Color color2 = Color.Black;
//YCbCr yCbCr2 = color2;
//Assert.Equal(0, yCbCr2.Y, 0);
//Assert.Equal(128, yCbCr2.Cb, 0);
//Assert.Equal(128, yCbCr2.Cr, 0);
//// Gray
//Color color3 = Color.Gray;
//YCbCr yCbCr3 = color3;
//Assert.Equal(128, yCbCr3.Y, 0);
//Assert.Equal(128, yCbCr3.Cb, 0);
//Assert.Equal(128, yCbCr3.Cr, 0);
}
/// <summary>

Write Preview
Loading…
Cancel
Save