public void GetHuffmanEncodingLength_Zero()
{
int expected = 0;
int actual = HuffmanScanEncoder.GetHuffmanEncodingLength(0);
Assert.Equal(expected, actual);
}
static void RunTest()
{
Block8x8F data = default;
int expectedLessThan = 1;
int actual = HuffmanScanEncoder.GetLastValuableElementIndex(ref data);
Assert.True(actual < expectedLessThan);
}
public void GetHuffmanEncodingLength_Random(int seed)
{
int maxNumber = 1 << 16;
var rng = new Random(seed);
for (int i = 0; i < 1000; i++)
{
uint number = (uint)rng.Next(0, maxNumber);
int expected = GetHuffmanEncodingLength_Reference(number);
int actual = HuffmanScanEncoder.GetHuffmanEncodingLength(number);
Assert.Equal(expected, actual);
}
}
/// <summary>
/// Encode writes the image to the jpeg baseline format with the given options.
/// </summary>
/// <typeparam name="TPixel">The pixel format.</typeparam>
/// <param name="image">The image to write from.</param>
/// <param name="stream">The stream to write to.</param>
/// <param name="cancellationToken">The token to request cancellation.</param>
public void Encode <TPixel>(Image <TPixel> image, Stream stream, CancellationToken cancellationToken)
where TPixel : unmanaged, IPixel <TPixel>
{
Guard.NotNull(image, nameof(image));
Guard.NotNull(stream, nameof(stream));
if (image.Width >= JpegConstants.MaxLength || image.Height >= JpegConstants.MaxLength)
{
JpegThrowHelper.ThrowDimensionsTooLarge(image.Width, image.Height);
}
cancellationToken.ThrowIfCancellationRequested();
this.outputStream = stream;
ImageMetadata metadata = image.Metadata;
JpegMetadata jpegMetadata = metadata.GetJpegMetadata();
// If the color type was not specified by the user, preserve the color type of the input image, if it's a supported color type.
if (!this.colorType.HasValue && IsSupportedColorType(jpegMetadata.ColorType))
{
this.colorType = jpegMetadata.ColorType;
}
// Compute number of components based on color type in options.
int componentCount = (this.colorType == JpegColorType.Luminance) ? 1 : 3;
ReadOnlySpan <byte> componentIds = this.GetComponentIds();
// TODO: Right now encoder writes both quantization tables for grayscale images - we shouldn't do that
// Initialize the quantization tables.
this.InitQuantizationTables(componentCount, jpegMetadata, out Block8x8F luminanceQuantTable, out Block8x8F chrominanceQuantTable);
// Write the Start Of Image marker.
this.WriteStartOfImage();
// Do not write APP0 marker for RGB colorspace.
if (this.colorType != JpegColorType.Rgb)
{
this.WriteJfifApplicationHeader(metadata);
}
// Write Exif, ICC and IPTC profiles
this.WriteProfiles(metadata);
if (this.colorType == JpegColorType.Rgb)
{
// Write App14 marker to indicate RGB color space.
this.WriteApp14Marker();
}
// Write the quantization tables.
this.WriteDefineQuantizationTables(ref luminanceQuantTable, ref chrominanceQuantTable);
// Write the image dimensions.
this.WriteStartOfFrame(image.Width, image.Height, componentCount, componentIds);
// Write the Huffman tables.
this.WriteDefineHuffmanTables(componentCount);
// Write the scan header.
this.WriteStartOfScan(componentCount, componentIds);
// Write the scan compressed data.
var scanEncoder = new HuffmanScanEncoder(stream);
if (this.colorType == JpegColorType.Luminance)
{
// luminance quantization table only.
scanEncoder.EncodeGrayscale(image, ref luminanceQuantTable, cancellationToken);
}
else
{
// luminance and chrominance quantization tables.
switch (this.colorType)
{
case JpegColorType.YCbCrRatio444:
case JpegColorType.Luminance:
scanEncoder.Encode444(image, ref luminanceQuantTable, ref chrominanceQuantTable, cancellationToken);
break;
case JpegColorType.YCbCrRatio420:
scanEncoder.Encode420(image, ref luminanceQuantTable, ref chrominanceQuantTable, cancellationToken);
break;
case JpegColorType.Rgb:
scanEncoder.EncodeRgb(image, ref luminanceQuantTable, cancellationToken);
break;
}
}
// Write the End Of Image marker.
this.WriteEndOfImageMarker();
stream.Flush();
}
