Encoder.Quality フィールドとは何？わかりやすく解説 Weblio辞書

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.NET Framework クラスライブラリリファレンス

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Encoder.Quality フィールド

品質パラメータカテゴリのグローバル一意識別子を使用して初期化される Encoder オブジェクトを表します。

名前空間: System.Drawing.Imaging
アセンブリ: System.Drawing (system.drawing.dll 内)
構文

Visual Basic (宣言)

Public Shared ReadOnly Quality
 As Encoder

Visual Basic (使用法)

Dim value As Encoder

value = Encoder.Quality

public static readonly Encoder Quality

C++

public:
static initonly Encoder^ Quality

public static final Encoder Quality

JScript

public static final var
 Quality : Encoder

解説

Quality カテゴリは、イメージの圧縮レベルを指定します。EncoderParameter を構築するために使用する場合、品質カテゴリに有効な値の範囲は 0 ～ 100 です。低い数値を指定するほど、圧縮率が高くなり、イメージの品質は低下します。品質は 0 で最低、100 で最高になります。

使用例

BMP ファイルから Bitmap オブジェクトを作成する例を次に示します。このコードは、それぞれ品質レベルの異なる 3 つの JPEG ファイルにビットマップを保存します。

Visual Basic

Imports System
Imports System.Drawing
Imports System.Drawing.Imaging


Class Example_SetJPEGQuality

    Public Shared Sub Main()
        Dim myBitmap As Bitmap
        Dim myImageCodecInfo As ImageCodecInfo
        Dim myEncoder As Encoder
        Dim myEncoderParameter As EncoderParameter
        Dim myEncoderParameters As EncoderParameters

        ' Create a Bitmap object based on a BMP file.
        myBitmap = New Bitmap("Shapes.bmp")

        ' Get an ImageCodecInfo object that represents the JPEG codec.
        myImageCodecInfo = GetEncoderInfo("image/jpeg")

        ' Create an Encoder object based on the GUID
        ' for the Quality parameter category.
        myEncoder = Encoder.Quality

        ' Create an EncoderParameters object.
        ' An EncoderParameters object has an array of EncoderParameter
        ' objects. In this case, there is only one
        ' EncoderParameter object in the array.
        myEncoderParameters = New EncoderParameters(1)

        ' Save the bitmap as a JPEG file with quality level 25.
        myEncoderParameter = New EncoderParameter(myEncoder, CType(25L,
 Int32))
        myEncoderParameters.Param(0) = myEncoderParameter
        myBitmap.Save("Shapes025.jpg", myImageCodecInfo,
 myEncoderParameters)

        ' Save the bitmap as a JPEG file with quality level 50.
        myEncoderParameter = New EncoderParameter(myEncoder, CType(50L,
 Int32))
        myEncoderParameters.Param(0) = myEncoderParameter
        myBitmap.Save("Shapes050.jpg", myImageCodecInfo,
 myEncoderParameters)

        ' Save the bitmap as a JPEG file with quality level 75.
        myEncoderParameter = New EncoderParameter(myEncoder, CType(75L,
 Int32))
        myEncoderParameters.Param(0) = myEncoderParameter
        myBitmap.Save("Shapes075.jpg", myImageCodecInfo,
 myEncoderParameters)

    End Sub 'Main

    Private Shared Function
 GetEncoderInfo(ByVal mimeType As String)
 As ImageCodecInfo
        Dim j As Integer
        Dim encoders() As ImageCodecInfo
        encoders = ImageCodecInfo.GetImageEncoders()

        j = 0
        While j < encoders.Length
            If encoders(j).MimeType = mimeType Then
                Return encoders(j)
            End If
            j += 1
        End While
        Return Nothing

    End Function 'GetEncoderInfo
End Class 'Example_SetJPEGQuality

using System;
using System.Drawing;
using System.Drawing.Imaging;
class Example_SetJPEGQuality
{
    public static void Main()
    {
        Bitmap myBitmap;
        ImageCodecInfo myImageCodecInfo;
        Encoder myEncoder;
        EncoderParameter myEncoderParameter;
        EncoderParameters myEncoderParameters;
                     
        // Create a Bitmap object based on a BMP file.
        myBitmap = new Bitmap("Shapes.bmp");
                     
        // Get an ImageCodecInfo object that represents the JPEG codec.
        myImageCodecInfo = GetEncoderInfo("image/jpeg");
                     
        // Create an Encoder object based on the GUID
                     
        // for the Quality parameter category.
        myEncoder = Encoder.Quality;
                     
        // Create an EncoderParameters object.
                     
        // An EncoderParameters object has an array of EncoderParameter
                     
        // objects. In this case, there is only one
                     
        // EncoderParameter object in the array.
        myEncoderParameters = new EncoderParameters(1);
                     
        // Save the bitmap as a JPEG file with quality level 25.
        myEncoderParameter = new EncoderParameter(myEncoder, 25L);
        myEncoderParameters.Param[0] = myEncoderParameter;
        myBitmap.Save("Shapes025.jpg", myImageCodecInfo, myEncoderParameters);
                     
        // Save the bitmap as a JPEG file with quality level 50.
        myEncoderParameter = new EncoderParameter(myEncoder, 50L);
        myEncoderParameters.Param[0] = myEncoderParameter;
        myBitmap.Save("Shapes050.jpg", myImageCodecInfo, myEncoderParameters);
                     
        // Save the bitmap as a JPEG file with quality level 75.
        myEncoderParameter = new EncoderParameter(myEncoder, 75L);
        myEncoderParameters.Param[0] = myEncoderParameter;
        myBitmap.Save("Shapes075.jpg", myImageCodecInfo, myEncoderParameters);
    }
    private static ImageCodecInfo GetEncoderInfo(String
 mimeType)
    {
        int j;
        ImageCodecInfo[] encoders;
        encoders = ImageCodecInfo.GetImageEncoders();
        for(j = 0; j < encoders.Length; ++j)
        {
            if(encoders[j].MimeType == mimeType)
                return encoders[j];
        }
        return null;
    }
}

C++

#using <System.Drawing.dll>

using namespace System;
using namespace System::Drawing;
using namespace System::Drawing::Imaging;
static ImageCodecInfo^ GetEncoderInfo( String^ mimeType );
int main()
{
   Bitmap^ myBitmap;
   ImageCodecInfo^ myImageCodecInfo;
   Encoder^ myEncoder;
   EncoderParameter^ myEncoderParameter;
   EncoderParameters^ myEncoderParameters;
   
   // Create a Bitmap object based on a BMP file.
   myBitmap = gcnew Bitmap( "Shapes.bmp" );
   
   // Get an ImageCodecInfo object that represents the JPEG codec.
   myImageCodecInfo = GetEncoderInfo( "image/jpeg" );
   
   // Create an Encoder object based on the GUID
   // for the Quality parameter category.
   myEncoder = Encoder::Quality;
   
   // Create an EncoderParameters object.
   // An EncoderParameters object has an array of EncoderParameter
   // objects. In this case, there is only one
   // EncoderParameter object in the array.
   myEncoderParameters = gcnew EncoderParameters( 1 );
   
   // Save the bitmap as a JPEG file with quality level 25.
   myEncoderParameter = gcnew EncoderParameter( myEncoder,__int64(25) );
   myEncoderParameters->Param[ 0 ] = myEncoderParameter;
   myBitmap->Save( "Shapes025.jpg", myImageCodecInfo, myEncoderParameters
 );
   
   // Save the bitmap as a JPEG file with quality level 50.
   myEncoderParameter = gcnew EncoderParameter( myEncoder,__int64(50) );
   myEncoderParameters->Param[ 0 ] = myEncoderParameter;
   myBitmap->Save( "Shapes050.jpg", myImageCodecInfo, myEncoderParameters
 );
   
   // Save the bitmap as a JPEG file with quality level 75.
   myEncoderParameter = gcnew EncoderParameter( myEncoder,__int64(75) );
   myEncoderParameters->Param[ 0 ] = myEncoderParameter;
   myBitmap->Save( "Shapes075.jpg", myImageCodecInfo, myEncoderParameters
 );
}

static ImageCodecInfo^ GetEncoderInfo( String^ mimeType )
{
   int j;
   array<ImageCodecInfo^>^encoders;
   encoders = ImageCodecInfo::GetImageEncoders();
   for ( j = 0; j < encoders->Length; ++j )
   {
      if ( encoders[ j ]->MimeType == mimeType )
            return encoders[ j ];

   }
   return nullptr;
}

import System.* ;
import System.Drawing.* ;
import System.Drawing.Imaging.* ;

class Example_SetJPEGQuality
{
    public static void main(String[]
 args)
    {
        Bitmap myBitmap;
        ImageCodecInfo myImageCodecInfo;
        Encoder myEncoder;
        EncoderParameter myEncoderParameter;
        EncoderParameters myEncoderParameters;
        
        // Create a Bitmap object based on a BMP file.
        myBitmap = new Bitmap("Shapes.bmp");
        
        // Get an ImageCodecInfo object that represents the JPEG codec.
        myImageCodecInfo = GetEncoderInfo("image/jpeg");
        
        // Create an Encoder object based on the GUID
        // for the Quality parameter category.
        myEncoder = Encoder.Quality;
        
        // Create an EncoderParameters object.
        // An EncoderParameters object has an array of EncoderParameter
        // objects. In this case, there is only one
        // EncoderParameter object in the array.
        myEncoderParameters = new EncoderParameters(1);
        
        // Save the bitmap as a JPEG file with quality level 25.
        myEncoderParameter = new EncoderParameter(myEncoder, 25L);
        myEncoderParameters.get_Param().set_Item( 0 , myEncoderParameter );
        myBitmap.Save("Shapes025.jpg", myImageCodecInfo, myEncoderParameters);
        
        // Save the bitmap as a JPEG file with quality level 50.
        myEncoderParameter = new EncoderParameter(myEncoder, 50L);
        myEncoderParameters.get_Param().set_Item( 0 , myEncoderParameter );
        myBitmap.Save("Shapes050.jpg", myImageCodecInfo, myEncoderParameters);
        
        // Save the bitmap as a JPEG file with quality level 75.
        myEncoderParameter = new EncoderParameter(myEncoder, 75L);
        myEncoderParameters.get_Param().set_Item( 0 , myEncoderParameter );
        myBitmap.Save("Shapes075.jpg", myImageCodecInfo, myEncoderParameters);
    } //main
   
    private static ImageCodecInfo GetEncoderInfo(String
 mimeType) 
    {
        int j;
        ImageCodecInfo encoders[];
        encoders = ImageCodecInfo.GetImageEncoders();
        for(j = 0; j < encoders.length; j++) {
            if ( encoders[j].get_MimeType().Equals(mimeType))
 {
                return encoders[j];
            }
        } 
        return null ;
    } //GetEncoderInfo
} //Example_SetJPEGQuality

プラットフォーム

バージョン情報

.NET Framework
サポート対象 : 2.0、1.1、1.0

参照

関連項目
Encoder クラス
Encoder メンバ
System.Drawing.Imaging 名前空間

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Encoder.Quality フィールドとは？ わかりやすく解説

Encoder.Quality フィールド

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Encoder.Quality フィールドとは？わかりやすく解説