ImageGear for .NET
ImGearDecimationTypes Enumeration
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ImageGear21.Core Assembly > ImageGear.Formats.JPG Namespace : ImGearDecimationTypes Enumeration




Glossary Item Box

This enumeration lists all possible JPEG decimation values.

Syntax

 
Visual Basic
C#
Managed Extensions for C++
C++/CLI
 
 

Members

MemberValueDescription
Decim_1x1_1x1_1x10For each Y sample, one Cb sample and one Cr sample are stored.
Decim_1x2_1x1_1x12For each vertical pair of Y samples, one Cb sample and one Cr sample are stored.
Decim_1x4_1x1_1x18For each four vertical Y samples, one Cb sample and one Cr sample are stored.
Decim_1x4_1x2_1x210For each four vertical Y samples, two vertical Cb samples and two vertical Cr samples are stored.
Decim_2x1_1x1_1x11For each horizontal pair of Y samples, one Cb sample and one Cr sample are stored.
Decim_2x2_1x1_1x13For each four (two horizontal by two vertical) Y samples, one Cb sample and one Cr sample are stored.
Decim_2x2_2x1_2x14For each four (two horizontal by two vertical) Y samples, two horizontal Cb samples and two horizontal Cr samples are stored.
Decim_2x4_1x1_1x16For each eight (two horizontal by four vertical) Y samples, one Cb sample and one Cr sample are stored.
Decim_4x1_1x1_1x17For each four horizontal Y samples, one Cb sample and one Cr sample are stored.
Decim_4x1_2x1_2x19For each four horizontal Y samples, two horizontal Cb samples and two horizontal Cr samples are stored.
Decim_4x2_1x1_1x15For each eight (four horizontal by two vertical) Y samples, one Cb sample and one Cr sample are stored.
Decim_4x4_2x2_2x211For each 16 (four horizontal by four vertical) Y samples, four (two horizontal by two vertical) Cb samples and four (two horizontal by two vertical) Cr samples are stored.

Remarks

The format of these ImageGear decimation constants is: Decim_(H1)x(V1)_(H2)x(V2)_(H3)x(V3),

where Hi, Vi = horizontal and vertical decimation values for the i-channel.

The following is a simple example of decimation. For a more detailed definition, please see the JPEG Specification.

A decimation setting of Decim_4x2_1x1_1x1 would yield the following results:

As shown, 8 Y components in the source image have yielded one Cb and one Cr component. In general, this setting will reduce the quality of the compression, unless the image has many continuous tone areas.

Maximum quality can be reached using a value of Decim_1x1_1x1_1x1.

Maximum compression ratio can be reached with a value of Decim_4x4_2x2_2x2.

The ImageGear default decimation value is: Decim_2x2_1x1_1x1.

Inheritance Hierarchy

System.Object
   System.ValueType
      System.Enum
         ImageGear.Formats.JPG.ImGearDecimationTypes

See Also

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