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我花了很长时间在谷歌上搜索并阅读了各种文章，但我似乎一直在兜圈子，现在很困惑，似乎没有成功！

我正在尝试获取 4 个不同大小的图像版本，为了实现这一点，我有一个大小数组，并且正在循环下面的函数。

这行得通，并且完成了预期的一切，除了较小的图像非常块状，我无法获得平滑以达到我期望的效果。

对于老式的 ASP Classic，我使用了 Persits ASPUpload/jpeg 插件，它可以很好地平滑调整大小。使用 .NET，我正在苦苦挣扎。

Public Shared Sub ResizeImages(FileName, NewFileName, maxWidth, maxHeight, uploadDir, qualityPercent)

    Dim originalImg As System.Drawing.Image = System.Drawing.Image.FromFile(uploadDir & FileName)

    Dim aspectRatio As Double
    Dim newHeight As Integer
    Dim newWidth As Integer

    '*** Calculate Size ***'
    If originalImg.Width > maxWidth Or originalImg.Height > maxHeight Then
        If originalImg.Width >= originalImg.Height Then ' image is wider than tall
            newWidth = maxWidth
            aspectRatio = originalImg.Width / maxWidth
            newHeight = originalImg.Height / aspectRatio
        Else ' image is taller than wide
            newHeight = maxHeight
            aspectRatio = originalImg.Height / maxHeight
            newWidth = originalImg.Width / aspectRatio
        End If
    Else ' if image is not larger than max then keep original size
        newWidth = originalImg.Width
        newHeight = originalImg.Height
    End If

    Dim newImg As New Bitmap(originalImg, CInt(newWidth), CInt(newHeight)) '' blank canvas
    Dim canvas As Graphics = Graphics.FromImage(newImg) 'graphics element

    '*** compress ***'
    Dim myEncoderParameters As EncoderParameters
    myEncoderParameters = New EncoderParameters(1)
    ' set quality level based on "resolution" variable
    Dim myEncoderParameter = New EncoderParameter(System.Drawing.Imaging.Encoder.Quality, CType(qualityPercent, Int32))
    myEncoderParameters.Param(0) = myEncoderParameter

    '*** Save As  ***'
    canvas.SmoothingMode = Drawing.Drawing2D.SmoothingMode.AntiAlias
    canvas.DrawImage(newImg, New Point(0, 0))
    newImg.Save(uploadDir & NewFileName, getCodec("image/jpeg"), myEncoderParameters)

    '*** Close ***'
    originalImg.Dispose()
    newImg.Dispose()
    '*** Nothing ***'
    newImg = Nothing
    originalImg = Nothing

End Sub

Public Shared Function getCodec(getThis) As Drawing.Imaging.ImageCodecInfo
    Dim output As Drawing.Imaging.ImageCodecInfo
    Dim codecs As Imaging.ImageCodecInfo() = Imaging.ImageCodecInfo.GetImageEncoders
    For Each codec As Imaging.ImageCodecInfo In codecs
        If codec.MimeType = getThis Then
            output = codec
        End If
    Next codec
    Return output
End Function

我觉得我可能在这里混淆了类型？

在执行上述函数的过程中，我有 a System.Drawing.Image、 aBitMap和一个Graphic对象，并且觉得我可能试图将平滑应用于错误的元素，或者在编码的错误阶段？

该System.Drawing.Image对象加载保存在服务器上的文件，然后我计算所需的纵横比和新大小，创建一个BitMap此大小的新文件并将其保存到Graphics对象中。

它是否正确？

我需要修改什么来实现更平滑的调整大小？

像往常一样，非常感谢任何帮助。

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1 回答 1

2

尝试使用InterpolationMode

Private imgSource As System.Drawing.Image
Private imgOutput As System.Drawing.Image
Public Function Resize(ByVal intPercent As Integer, ByVal intType As Integer)
    'resize the image by percent
    Dim intX, intY As Integer
    intX = Int(imgSource.Width / 100 * intPercent)
    intY = Int(imgSource.Height / 100 * intPercent)
    Dim bm As Drawing.Bitmap = New System.Drawing.Bitmap(intX, intY)
    Dim g As System.Drawing.Graphics = Drawing.Graphics.FromImage(bm)

    Select Case intType
        Case 0
            g.InterpolationMode = Drawing.Drawing2D.InterpolationMode.Default
        Case 1
            g.InterpolationMode = Drawing.Drawing2D.InterpolationMode.High
        Case 2
            g.InterpolationMode = Drawing.Drawing2D.InterpolationMode.HighQualityBilinear
        Case 3
            g.InterpolationMode = Drawing.Drawing2D.InterpolationMode.HighQualityBicubic
    End Select

    g.DrawImage(imgSource, 0, 0, intX, intY)
    imgOutput = bm

End Function
于 2012-06-28T12:40:59.993 回答