@ -14,14 +14,24 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
internal unsafe struct JpegBlockPostProcessor
{
/// <summary>
/// The <see cref="ComputationData"/>
/// Source block
/// </summary>
private ComputationData data ;
public Block8x8F SourceBlock ;
/// <summary>
/// Pointers to elements of <see cref="data"/>
/// Temporal block 1 to store intermediate and/or final computation results
/// </summary>
private DataPointers pointers ;
public Block8x8F WorkspaceBlock1 ;
/// <summary>
/// Temporal block 2 to store intermediate and/or final computation results
/// </summary>
public Block8x8F WorkspaceBlock2 ;
/// <summary>
/// The quantization table as <see cref="Block8x8F"/>
/// </summary>
public Block8x8F DequantiazationTable ;
private Size subSamplingDivisors ;
@ -30,11 +40,8 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
/// </summary>
public static void Init ( JpegBlockPostProcessor * postProcessor , IRawJpegData decoder , IJpegComponent component )
{
postProcessor - > data = ComputationData . Create ( ) ;
postProcessor - > pointers = new DataPointers ( & postProcessor - > data ) ;
int qtIndex = component . QuantizationTableIndex ;
postProcessor - > data . DequantiazationTable = ZigZag . CreateDequantizationTable ( ref decoder . QuantizationTables [ qtIndex ] ) ;
postProcessor - > DequantiazationTable = ZigZag . CreateDequantizationTable ( ref decoder . QuantizationTables [ qtIndex ] ) ;
postProcessor - > subSamplingDivisors = component . SubSamplingDivisors ;
}
@ -42,110 +49,28 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Common.Decoder
ref Block8x8 sourceBlock ,
BufferArea < float > destArea )
{
sourceBlock . CopyToFloatBlock ( ref this . data . SourceBlock ) ;
Block8x8F * b = this . pointers . SourceBlock ;
ref Block8x8F b = ref this . SourceBlock ;
sourceBlock . CopyToFloatBlock ( ref b ) ;
// Dequantize:
b - > MultiplyInplace ( ref this . data . DequantiazationTable ) ;
b . MultiplyInplace ( ref this . DequantiazationTable ) ;
FastFloatingPointDCT . TransformIDCT ( ref * b , ref this . data . WorkspaceBlock1 , ref this . data . WorkspaceBlock2 ) ;
this . data . WorkspaceBlock1 . NormalizeColorsInplace ( ) ;
FastFloatingPointDCT . TransformIDCT ( ref b , ref this . WorkspaceBlock1 , ref this . WorkspaceBlock2 ) ;
// To conform better to libjpeg we actually NEED TO loose precision here.
// This is because they store blocks as Int16 between all the operations.
// Unfortunately, we need to emulate this to be "more accurate" :(
this . data . WorkspaceBlock1 . RoundInplace ( ) ;
this . data . WorkspaceBlock1 . CopyTo ( destArea , this . subSamplingDivisors . Width , this . subSamplingDivisors . Height ) ;
}
/// <summary>
/// Holds the "large" data blocks needed for computations.
/// </summary>
[StructLayout(LayoutKind.Sequential)]
public struct ComputationData
{
/// <summary>
/// Source block
/// </summary>
public Block8x8F SourceBlock ;
/// <summary>
/// Temporal block 1 to store intermediate and/or final computation results
/// </summary>
public Block8x8F WorkspaceBlock1 ;
/// <summary>
/// Temporal block 2 to store intermediate and/or final computation results
/// </summary>
public Block8x8F WorkspaceBlock2 ;
/// <summary>
/// The quantization table as <see cref="Block8x8F"/>
/// </summary>
public Block8x8F DequantiazationTable ;
/// <summary>
/// The jpeg unzig data
/// </summary>
public ZigZag Unzig ;
/// <summary>
/// Creates and initializes a new <see cref="ComputationData"/> instance
/// </summary>
/// <returns>The <see cref="ComputationData"/></returns>
public static ComputationData Create ( )
// To be "more accurate", we need to emulate this by rounding!
if ( SimdUtils . IsAvx2CompatibleArchitecture )
{
var data = default ( ComputationData ) ;
data . Unzig = ZigZag . CreateUnzigTable ( ) ;
return data ;
this . WorkspaceBlock1 . NormalizeColorsAndRoundInplaceAvx2 ( ) ;
}
}
/// <summary>
/// Contains pointers to the memory regions of <see cref="ComputationData"/> so they can be easily passed around to pointer based utility methods of <see cref="Block8x8F"/>
/// </summary>
public struct DataPointers
{
/// <summary>
/// Pointer to <see cref="ComputationData.SourceBlock"/>
/// </summary>
public Block8x8F * SourceBlock ;
/// <summary>
/// Pointer to <see cref="ComputationData.WorkspaceBlock1"/>
/// </summary>
public Block8x8F * WorkspaceBlock1 ;
/// <summary>
/// Pointer to <see cref="ComputationData.WorkspaceBlock2"/>
/// </summary>
public Block8x8F * WorkspaceBlock2 ;
/// <summary>
/// Pointer to <see cref="ComputationData.DequantiazationTable"/>
/// </summary>
public Block8x8F * DequantiazationTable ;
/// <summary>
/// Pointer to <see cref="ComputationData.Unzig"/> as int*
/// </summary>
public int * Unzig ;
/// <summary>
/// Initializes a new instance of the <see cref="DataPointers" /> struct.
/// </summary>
/// <param name="dataPtr">Pointer to <see cref="ComputationData"/></param>
internal DataPointers ( ComputationData * dataPtr )
else
{
this . SourceBlock = & dataPtr - > SourceBlock ;
this . WorkspaceBlock1 = & dataPtr - > WorkspaceBlock1 ;
this . WorkspaceBlock2 = & dataPtr - > WorkspaceBlock2 ;
this . DequantiazationTable = & dataPtr - > DequantiazationTable ;
this . Unzig = dataPtr - > Unzig . Data ;
this . WorkspaceBlock1 . NormalizeColorsInplace ( ) ;
this . WorkspaceBlock1 . RoundInplace ( ) ;
}
this . WorkspaceBlock1 . CopyTo ( destArea , this . subSamplingDivisors . Width , this . subSamplingDivisors . Height ) ;
}
}
}
Anton Firszov
9 years ago