// the algorithm flow is based on:
// https://bitmiracle.github.io/libjpeg.net/help/articles/KB/decompression-details.html
private DecompressionResult DecompressJpgToRaw(byte[] image)
{
var cinfo = new jpeg_decompress_struct(new jpeg_error_mgr());
using (var memoryStream = new MemoryStream(image))
{
cinfo.jpeg_stdio_src(memoryStream);
cinfo.jpeg_read_header(true);
cinfo.Out_color_space = J_COLOR_SPACE.JCS_RGB;
cinfo.jpeg_start_decompress();
// there are 3 components: R, G, B
var rowStride = 3 * cinfo.Output_width;
var result = new byte[rowStride * cinfo.Output_height];
var resultOffset = 0;
var buffer = new byte[1][];
buffer[0] = new byte[rowStride];
while (cinfo.Output_scanline < cinfo.Output_height)
{
var ct = cinfo.jpeg_read_scanlines(buffer, 1);
if (ct > 0)
{
Array.Copy(buffer[0], 0, result, resultOffset, buffer[0].Length);
resultOffset += buffer[0].Length;
}
}
cinfo.jpeg_finish_decompress();
return(new DecompressionResult(result, cinfo.Output_width, cinfo.Output_height));
}
}
/// <summary>
/// Decompresses JPEG image to any image described as ICompressDestination
/// </summary>
/// <param name="jpeg">Stream with JPEG data</param>
/// <param name="destination">Stream for output of compressed JPEG</param>
public void Decompress(Stream jpeg, IDecompressDestination destination)
{
if (jpeg == null)
{
throw new ArgumentNullException("jpeg");
}
if (destination == null)
{
throw new ArgumentNullException("destination");
}
beforeDecompress(jpeg);
// Start decompression
m_decompressor.jpeg_start_decompress();
LoadedImageAttributes parameters = getImageParametersFromDecompressor();
destination.SetImageAttributes(parameters);
destination.BeginWrite();
/* Process data */
while (m_decompressor.Output_scanline < m_decompressor.Output_height)
{
byte[][] row = jpeg_common_struct.AllocJpegSamples(m_decompressor.Output_width * m_decompressor.Output_components, 1);
m_decompressor.jpeg_read_scanlines(row, 1);
destination.ProcessPixelsRow(row[0]);
}
destination.EndWrite();
// Finish decompression and release memory.
m_decompressor.jpeg_finish_decompress();
}
private void startDecompression(jpeg_decompress_struct jpeg)
{
m_input.Position = 0;
jpeg.Src = new VirtualStreamSourceManager(jpeg, m_input);
if (jpeg.jpeg_read_header(true) != ReadResult.JPEG_HEADER_OK)
{
throw new InvalidProgramException("Failed to decompress JPEG image data.");
}
var colorspace = jpeg.Out_color_space;
if (colorspace != J_COLOR_SPACE.JCS_GRAYSCALE &&
colorspace != J_COLOR_SPACE.JCS_RGB &&
colorspace != J_COLOR_SPACE.JCS_CMYK)
{
jpeg.Out_color_space = J_COLOR_SPACE.JCS_RGB;
}
if (!jpeg.jpeg_start_decompress())
{
throw new InvalidProgramException("Failed to decompress JPEG image data.");
}
}
private static void decompress(Stream input, DecompressOptions options, Stream output)
{
Debug.Assert(input != null);
Debug.Assert(options != null);
Debug.Assert(output != null);
/* Initialize the JPEG decompression object with default error handling. */
jpeg_decompress_struct cinfo = new jpeg_decompress_struct(new cd_jpeg_error_mgr());
/* Insert custom marker processor for COM and APP12.
* APP12 is used by some digital camera makers for textual info,
* so we provide the ability to display it as text.
* If you like, additional APPn marker types can be selected for display,
* but don't try to override APP0 or APP14 this way (see libjpeg.doc).
*/
cinfo.jpeg_set_marker_processor((int)JPEG_MARKER.COM, new jpeg_decompress_struct.jpeg_marker_parser_method(printTextMarker));
cinfo.jpeg_set_marker_processor((int)JPEG_MARKER.APP0 + 12, printTextMarker);
/* Specify data source for decompression */
cinfo.jpeg_stdio_src(input);
/* Read file header, set default decompression parameters */
cinfo.jpeg_read_header(true);
applyOptions(cinfo, options);
/* Initialize the output module now to let it override any crucial
* option settings (for instance, GIF wants to force color quantization).
*/
djpeg_dest_struct dest_mgr = null;
switch (options.OutputFormat)
{
case IMAGE_FORMATS.FMT_BMP:
dest_mgr = new bmp_dest_struct(cinfo, false);
break;
case IMAGE_FORMATS.FMT_OS2:
dest_mgr = new bmp_dest_struct(cinfo, true);
break;
default:
cinfo.ERREXIT((int)ADDON_MESSAGE_CODE.JERR_UNSUPPORTED_FORMAT);
break;
}
dest_mgr.output_file = output;
/* Start decompressor */
cinfo.jpeg_start_decompress();
/* Write output file header */
dest_mgr.start_output();
/* Process data */
while (cinfo.Output_scanline < cinfo.Output_height)
{
int num_scanlines = cinfo.jpeg_read_scanlines(dest_mgr.buffer, dest_mgr.buffer_height);
dest_mgr.put_pixel_rows(num_scanlines);
}
/* Finish decompression and release memory.
* I must do it in this order because output module has allocated memory
* of lifespan JPOOL_IMAGE; it needs to finish before releasing memory.
*/
dest_mgr.finish_output();
cinfo.jpeg_finish_decompress();
/* All done. */
if (cinfo.Err.Num_warnings != 0)
{
Console.WriteLine("Corrupt-data warning count is not zero");
}
}
static string outfilename; /* for -outfile switch */
public static void Main(string[] args)
{
progname = Path.GetFileName(Environment.GetCommandLineArgs()[0]);
/* Initialize the JPEG decompression object with default error handling. */
cd_jpeg_error_mgr err = new cd_jpeg_error_mgr();
jpeg_decompress_struct cinfo = new jpeg_decompress_struct(err);
/* Insert custom marker processor for COM and APP12.
* APP12 is used by some digital camera makers for textual info,
* so we provide the ability to display it as text.
* If you like, additional APPn marker types can be selected for display,
* but don't try to override APP0 or APP14 this way (see libjpeg.doc).
*/
cinfo.jpeg_set_marker_processor((int)JPEG_MARKER.COM, new jpeg_decompress_struct.jpeg_marker_parser_method(print_text_marker));
cinfo.jpeg_set_marker_processor((int)JPEG_MARKER.APP0 + 12, print_text_marker);
/* Scan command line to find file names. */
/* It is convenient to use just one switch-parsing routine, but the switch
* values read here are ignored; we will rescan the switches after opening
* the input file.
* (Exception: tracing level set here controls verbosity for COM markers
* found during jpeg_read_header...)
*/
int file_index;
if (!parse_switches(cinfo, args, false, out file_index))
{
usage();
return;
}
/* Must have either -outfile switch or explicit output file name */
if (outfilename == null)
{
// file_index should point to input file
if (file_index != args.Length - 2)
{
Console.WriteLine(string.Format("{0}: must name one input and one output file.", progname));
usage();
return;
}
// output file comes right after input one
outfilename = args[file_index + 1];
}
else
{
// file_index should point to input file
if (file_index != args.Length - 1)
{
Console.WriteLine(string.Format("{0}: must name one input and one output file.", progname));
usage();
return;
}
}
/* Open the input file. */
FileStream input_file = null;
if (file_index < args.Length)
{
try
{
input_file = new FileStream(args[file_index], FileMode.Open);
}
catch (Exception e)
{
Console.WriteLine(string.Format("{0}: can't open {1}", progname, args[file_index]));
Console.WriteLine(e.Message);
return;
}
}
else
{
Console.WriteLine(string.Format("{0}: sorry, can't read file from console"));
return;
}
/* Open the output file. */
FileStream output_file = null;
if (outfilename != null)
{
try
{
output_file = new FileStream(outfilename, FileMode.Create);
}
catch (Exception e)
{
Console.WriteLine(string.Format("{0}: can't open {1}", progname, args[file_index]));
Console.WriteLine(e.Message);
return;
}
}
else
{
Console.WriteLine(string.Format("{0}: sorry, can't write file to console"));
return;
}
/* Specify data source for decompression */
cinfo.jpeg_stdio_src(input_file);
/* Read file header, set default decompression parameters */
cinfo.jpeg_read_header(true);
/* Adjust default decompression parameters by re-parsing the options */
parse_switches(cinfo, args, true, out file_index);
/* Initialize the output module now to let it override any crucial
* option settings (for instance, GIF wants to force color quantization).
*/
djpeg_dest_struct dest_mgr = null;
switch (requested_fmt)
{
case IMAGE_FORMATS.FMT_BMP:
dest_mgr = new bmp_dest_struct(cinfo, false);
break;
case IMAGE_FORMATS.FMT_OS2:
dest_mgr = new bmp_dest_struct(cinfo, true);
break;
default:
cinfo.ERREXIT((int)ADDON_MESSAGE_CODE.JERR_UNSUPPORTED_FORMAT);
break;
}
dest_mgr.output_file = output_file;
/* Start decompressor */
cinfo.jpeg_start_decompress();
/* Write output file header */
dest_mgr.start_output();
/* Process data */
while (cinfo.Output_scanline < cinfo.Output_height)
{
int num_scanlines = cinfo.jpeg_read_scanlines(dest_mgr.buffer, dest_mgr.buffer_height);
dest_mgr.put_pixel_rows(num_scanlines);
}
/* Finish decompression and release memory.
* I must do it in this order because output module has allocated memory
* of lifespan JPOOL_IMAGE; it needs to finish before releasing memory.
*/
dest_mgr.finish_output();
cinfo.jpeg_finish_decompress();
/* Close files, if we opened them */
input_file.Close();
input_file.Dispose();
output_file.Close();
output_file.Dispose();
/* All done. */
if (cinfo.Err.Num_warnings != 0)
{
Console.WriteLine("Corrupt-data warning count is not zero");
}
}