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JpegEncoderOptions Class

This class holds possible JPEG format encoder options.

Namespace: Aurigma.GraphicsMill.Codecs
Assembly: Aurigma.GraphicsMill (in Aurigma.GraphicsMill.dll)

Syntax

Visual Basic 
Public NotInheritable Class JpegEncoderOptions _
	Inherits EncoderOptions
C# 
public sealed class JpegEncoderOptions : EncoderOptions

Remarks

The main JPEG encoder setting is a quality/file size ratio. It is specified with Quality property. This property accepts values in range [0, 100] where 0 means the lowest quality (but smallest file size) and 100 means the highest quality (but largest file size).

Besides of this you can specify is JPEG should be progressive (using IsProgressive). It allows the browsers to display the JPEG file while it is being downloaded (displaying more and more details upon new file portions download). Unfortunately this feature is not supported with Internet Explorer browser.

Another compression setting can be changed via ChromaSubsamplingEnabled property. Chroma subsampling is one of the compression methods used in JPEG. It is based on the specific of the human vision and allows to reduce size of the result file by storing color information at lower resolution than luminance information. In most cases this tradeoff will not be noticeable to the human. But sometimes such information loss may be significant (e.g. for some classes of image processing algorithms) and chroma subsampling should be turned off. Chroma subsampling is enabled by default.

Also you can provide meta-information for encoding. Use AdobeResources, Exif and Iptc properties to specify corresponding metadata objects.

MediaFormat property of this class always returns value that equals to JpegFormat static field of the FormatManager class. Left and Top are meaningless for JPEG and always set to 0.

Examples

This code sample demonstrates how to save the JPEG file with non-default encoder settings. Here we set low quality and make JPEG to be progressive (good for fast delivery via Web):

Visual Basic 
Dim bitmap As New Aurigma.GraphicsMill.Bitmap("c:\Mountain.jpg")

bitmap.Save("C:\Mountain2.jpg", _
    New Aurigma.GraphicsMill.Codecs.JpegEncoderOptions(50, True))

bitmap.Dispose()
C# 
using (Aurigma.GraphicsMill.Bitmap bitmap = 
        new Aurigma.GraphicsMill.Bitmap(@"c:\Mountain.jpg"))
{
    bitmap.Save(@"C:\Mountain2.jpg", 
        new Aurigma.GraphicsMill.Codecs.JpegEncoderOptions(50, true));
}

JPEG files can store EXIF and IPTC data blocks. Graphics Mill for .NET allows you extracting this data from the JPEG file and save it into another JPEG file (as well as into the other file format which supports EXIF and IPTC). This code sample demonstrates how to add the EXIF and IPTC data to the file:

Visual Basic 
Dim bitmap As New Aurigma.GraphicsMill.Bitmap("c:\Mountain.jpg")

Dim encoderOptions As New Aurigma.GraphicsMill.Codecs.JpegEncoderOptions(50, True)

'EXIF
Dim exif As New Aurigma.GraphicsMill.Codecs.ExifDictionary
exif(Aurigma.GraphicsMill.Codecs.ExifDictionary.Software) = "Aurigma Graphics Mill"
encoderOptions.Exif = exif

'IPTC
Dim iptc As New Aurigma.GraphicsMill.Codecs.IptcDictionary
iptc(Aurigma.GraphicsMill.Codecs.IptcDictionary.Category) = "Nature"
iptc(Aurigma.GraphicsMill.Codecs.IptcDictionary.CopyrightNotice) = "Aurigma Inc."
iptc(Aurigma.GraphicsMill.Codecs.IptcDictionary.Keyword) = "mountain"

encoderOptions.Iptc = iptc

'Adobe resource blocks
Dim adobeResources As New Aurigma.GraphicsMill.Codecs.AdobeResourceDictionary
'Create new adobe image resource block with the required metadata
Dim arBlock As New Aurigma.GraphicsMill.Codecs.AdobeResourceBlock("Copyright", New Byte() {1})
'Set this block to the item with 0x040A ID (copyright flag)
adobeResources.Item(&H40A) = arBlock

encoderOptions.AdobeResources = adobeResources

'XMP
Dim xmp As New Aurigma.GraphicsMill.Codecs.XmpData()
'Create a node with the required metadata
Dim node As New Aurigma.GraphicsMill.Codecs.XmpValueNode( _
    Aurigma.GraphicsMill.Codecs.XmpNodeType.SimpleProperty, _
    "John Doe", _
    Aurigma.GraphicsMill.Codecs.XmpTagNames.DCCreator)
xmp.AddNode(node)

encoderOptions.Xmp = xmp.Save()

bitmap.Save("C:\Mountain2.jpg", encoderOptions)

bitmap.Dispose()
C# 
using (Aurigma.GraphicsMill.Bitmap bitmap = 
           new Aurigma.GraphicsMill.Bitmap(@"c:\Mountain.jpg"))
{                
    Aurigma.GraphicsMill.Codecs.JpegEncoderOptions encoderOptions =
        new Aurigma.GraphicsMill.Codecs.JpegEncoderOptions(50, true);

    //EXIF
    Aurigma.GraphicsMill.Codecs.ExifDictionary exif =
        new Aurigma.GraphicsMill.Codecs.ExifDictionary();
    exif[Aurigma.GraphicsMill.Codecs.ExifDictionary.Software] = "Aurigma Graphics Mill";

    encoderOptions.Exif = exif;
    
    //IPTC
    Aurigma.GraphicsMill.Codecs.IptcDictionary iptc =
        new Aurigma.GraphicsMill.Codecs.IptcDictionary();
    iptc[Aurigma.GraphicsMill.Codecs.IptcDictionary.Category] = "Nature";
    iptc[Aurigma.GraphicsMill.Codecs.IptcDictionary.CopyrightNotice] = "Aurigma Inc.";
    iptc[Aurigma.GraphicsMill.Codecs.IptcDictionary.Keyword] = "mountain";

    encoderOptions.Iptc = iptc;

    //Adobe resource blocks
     Aurigma.GraphicsMill.Codecs.AdobeResourceDictionary adobeResources = 
         new Aurigma.GraphicsMill.Codecs.AdobeResourceDictionary();
    //Create new adobe image resource block with the required metadata
    Aurigma.GraphicsMill.Codecs.AdobeResourceBlock arBlock = new
        Aurigma.GraphicsMill.Codecs.AdobeResourceBlock("Copyright", new byte[] { 1 });
    //Set this block to the item with 0x040A ID (copyright flag)
    adobeResources[0x040A] = arBlock;

    encoderOptions.AdobeResources = adobeResources;

    //XMP
    Aurigma.GraphicsMill.Codecs.XmpData xmp = new Aurigma.GraphicsMill.Codecs.XmpData();
    //Create a node with the required metadata
    Aurigma.GraphicsMill.Codecs.XmpValueNode node = new
        Aurigma.GraphicsMill.Codecs.XmpValueNode(
            Aurigma.GraphicsMill.Codecs.XmpNodeType.SimpleProperty,
            "John Doe",
            Aurigma.GraphicsMill.Codecs.XmpTagNames.DCCreator);
    xmp.AddNode(node);

    encoderOptions.Xmp = xmp.Save();

    bitmap.Save(@"C:\Mountain2.jpg", encoderOptions);
}

Inheritance Hierarchy

System.Object
L Aurigma.GraphicsMill.Codecs.EncoderOptions
L Aurigma.GraphicsMill.Codecs.JpegEncoderOptions

Thread Safety

Static members of this type are safe for multi-threaded operations. Instance members of this type are not safe for multi-threaded operations.

Object Model







See Also

Reference