BitMiracle.LibJpeg.Classic.jpeg_compress_struct.jpeg_set_quality C# (CSharp) Method

jpeg_compress_struct Class Documentation Usage Examples Of BitMiracle.LibJpeg.Classic.jpeg_compress_struct::jpeg_set_quality Show file Open project: prepare/HTML-Renderer

jpeg_set_quality() public method

Constructs JPEG quantization tables appropriate for the indicated quality setting.

Note that the exact mapping from quality values to tables may change in future IJG releases as more is learned about DCT quantization.

public jpeg_set_quality ( int quality, bool force_baseline ) : void
quality	int	The quality value is expressed on the 0..100 scale recommended by IJG.
force_baseline	bool	If true, then the quantization table entries are constrained /// to the range 1..255 for full JPEG baseline compatibility. In the current implementation, /// this only makes a difference for quality settings below 25, and it effectively prevents /// very small/low quality files from being generated. The IJG decoder is capable of reading /// the non-baseline files generated at low quality settings when force_baseline is false, /// but other decoders may not be.
return	void

        public void jpeg_set_quality(int quality, bool force_baseline)
        {
            /* Convert user 0-100 rating to percentage scaling */
            quality = jpeg_quality_scaling(quality);

            /* Set up standard quality tables */
            jpeg_set_linear_quality(quality, force_baseline);
        }

Usage Example

Example #1

Show file

File: Compression.cs Project: lygroup/libjpeg.net

        public void TestCompressorWithContextRows()
        {
            using (MemoryStream stream = new MemoryStream())
            {
                jpeg_compress_struct compressor = new jpeg_compress_struct(new jpeg_error_mgr());
                compressor.Image_height = 100;
                compressor.Image_width = 100;
                compressor.In_color_space = J_COLOR_SPACE.JCS_GRAYSCALE;
                compressor.Input_components = 1;
                compressor.jpeg_set_defaults();

                compressor.Dct_method = J_DCT_METHOD.JDCT_IFAST;
                compressor.Smoothing_factor = 94;
                compressor.jpeg_set_quality(75, true);
                compressor.jpeg_simple_progression();

                compressor.Density_unit = DensityUnit.Unknown;
                compressor.X_density = (short)96;
                compressor.Y_density = (short)96;

                compressor.jpeg_stdio_dest(stream);
                compressor.jpeg_start_compress(true);

                byte[][] rowForDecompressor = new byte[1][];
                int bytesPerPixel = 1;
                while (compressor.Next_scanline < compressor.Image_height)
                {
                    byte[] row = new byte[100 * bytesPerPixel]; // wasteful, but gets you 0 bytes every time - content is immaterial.
                    rowForDecompressor[0] = row;
                    compressor.jpeg_write_scanlines(rowForDecompressor, 1);
                }
                compressor.jpeg_finish_compress();

                byte[] bytes = stream.ToArray();

                string filename = "TestCompressorWithContextRows.jpg";
                File.WriteAllBytes(Tester.MapOutputPath(filename), bytes);
                FileAssert.AreEqual(Tester.MapExpectedPath(filename), Tester.MapOutputPath(filename));
            }
        }

All Usage Examples Of BitMiracle.LibJpeg.Classic.jpeg_compress_struct::jpeg_set_quality

jpeg_compress_struct

add_huff_table

fill_a_scan

fill_dc_scans

fill_scans

initial_setup

initialize

jinit_c_main_controller

jinit_c_master_control

jinit_compress_master

jpeg_abort_compress