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Uploaded picture sometimes blurry

Posted on 2007-12-05
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Last Modified: 2012-08-14
Hello, I need some advise and direction on my code below or a better way to accomplish my goal of allowing a user to upload an image to the server. When the image is uploaded I need to create a thumbnail and ensure the image is no wider than 400px. I'm using the code below which functions correctly for me but some users get blurry results for the image and thumb. I use photoshop for my picture adjustment and have no idea what others use. I have them convert their pictures to 400px width before uploading and still they sometimes come out blurry. I take the original picture and adjust in photoshop and bam it looks great!

Any advice or tweeks to my code would be greatly apreciated!

Here is what I'm working with:
Private Sub InsertPicture1()
        'Insert imageurl and username to db
        If fuPicture1.HasFile Then
            If ddlEventGroup.Visible = True Then

                Dim EventGroup As String = ddlEventGroup.Text.Trim
                Dim ImageUrL As String = (EventGroup + "_" + fuPicture1.FileName)
                Dim myConnection As OleDbConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; data source=" & Server.MapPath("~/App_Data/LandT.mdb"))
                Dim ad As OleDbDataAdapter = New OleDbDataAdapter("insert into EventPhotos ([EventGroup], [ImageURL]) values ('" & Replace(EventGroup, "'", "''") & "', '" & Replace(ImageUrL, "'", "''") & "')", myConnection)
                Dim ds As DataSet = New DataSet()
                ad.Fill(ds)

                'upload the picture
                Dim fileName As String = Server.HtmlEncode(fuPicture1.FileName)
                Dim extension As String = System.IO.Path.GetExtension(fileName)
                Dim newFileName As String = ddlEventGroup.Text + "_" + fileName
                Dim Path As String = Server.MapPath("~/EventPictures/" & newFileName)

                If (extension = ".jpeg") Or (extension = ".jpg") Or (extension = ".gif") Or (extension = ".JPEG") Or (extension = ".JPG") Or (extension = ".GIF") Then
                    fuPicture1.SaveAs(Path)

                    CreateImage(Path, Server.MapPath("~/EventPictures/Image/" & newFileName))
                    CreateThumbnail(Path, Server.MapPath("~/EventPictures/Thumb/" & newFileName))

                    lblErrorMessage.Text = ""
                Else
                    lblErrorMessage.Text = "Sorry, but the picture must be a .jpg, .gif"
                End If
                'delete original picture
                Dim PictueName As String = (ddlEventGroup.Text + "_" + fuPicture1.FileName)

                Dim filePath As String = ("~/EventPictures/" + PictueName)
                File.Delete(Server.MapPath(Trim(filePath)))

            Else
                If txtEventGroup.Visible = True Then
                    Dim EventGroup As String = txtEventGroup.Text.Trim

                    Dim ImageUrL As String = (EventGroup + "_" + fuPicture1.FileName)
                    Dim myConnection As OleDbConnection = New OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0; data source=" & Server.MapPath("~/App_Data/LandT.mdb"))
                    Dim ad As OleDbDataAdapter = New OleDbDataAdapter("insert into EventPhotos ([EventGroup], [ImageURL]) values ('" & Replace(EventGroup, "'", "''") & "', '" & Replace(ImageUrL, "'", "''") & "')", myConnection)
                    Dim ds As DataSet = New DataSet()
                    ad.Fill(ds)

                    'upload the picture
                    Dim fileName As String = Server.HtmlEncode(fuPicture1.FileName)
                    Dim extension As String = System.IO.Path.GetExtension(fileName)
                    Dim newFileName As String = txtEventGroup.Text + "_" + fileName
                    Dim Path As String = Server.MapPath("~/EventPictures/" & newFileName)

                    If (extension = ".jpeg") Or (extension = ".jpg") Or (extension = ".gif") Or (extension = ".JPEG") Or (extension = ".JPG") Or (extension = ".GIF") Then
                        fuPicture1.SaveAs(Path)

                        CreateImage(Path, Server.MapPath("~/EventPictures/Image/" & newFileName))
                        CreateThumbnail(Path, Server.MapPath("~/EventPictures/Thumb/" & newFileName))

                        lblErrorMessage.Text = ""
                    Else
                        lblErrorMessage.Text = "Sorry, but the picture must be a .jpg, or .gif"
                    End If
                    'delete original picture
                    Dim PictueName As String = (txtEventGroup.Text + "_" + fuPicture1.FileName)

                    Dim filePath As String = ("~/EventPictures/" + PictueName)
                    File.Delete(Server.MapPath(Trim(filePath)))

                Else
                End If
            End If
        End If
       
    End Sub

    Public Sub CreateImage(ByVal srcpath As String, ByVal destpath As String)

        Dim img As System.Drawing.Image = System.Drawing.Image.FromFile(srcpath)
        Dim imgRatio As Double = img.Width / img.Height
        Dim tnWidth As Double = 400
        Dim tnHeight As Double = 400
        If imgRatio > 1 Then
            tnHeight = (400 * img.Height) / img.Width
        Else
            tnWidth = (400 * img.Width) / img.Height
        End If
        Dim Image As System.Drawing.Image = img.GetThumbnailImage(tnWidth, tnHeight, Nothing, New System.IntPtr(0))
        Image.Save(destpath, ImageFormat.Jpeg)

        img.Dispose()
        Image.Dispose()

    End Sub

    Public Sub CreateThumbnail(ByVal srcpath As String, ByVal destpath As String)

        Dim img As System.Drawing.Image = System.Drawing.Image.FromFile(srcpath)
        Dim imgRatio As Double = img.Width / img.Height
        Dim tnWidth As Double = 100
        Dim tnHeight As Double = 100
        If imgRatio > 1 Then
            tnHeight = (100 * img.Height) / img.Width
        Else
            tnWidth = (100 * img.Width) / img.Height
        End If
        Dim Thumb As System.Drawing.Image = img.GetThumbnailImage(tnWidth, tnHeight, Nothing, New System.IntPtr(0))
        Thumb.Save(destpath, ImageFormat.Jpeg)
        img.Dispose()
        Thumb.Dispose()
    End Sub
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Question by:gogetsome
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2 Comments
 
LVL 29

Accepted Solution

by:
Göran Andersson earned 500 total points
ID: 20411468
The GetThumbnailImage method uses the embedded thumbnail of the image if there is one. The embedded thumbnail is rather small, so when it's enlarged to 400 pixels, it gets blurry.

Instead of using the GetThumbnailImage method, create a new Bitmap object with the desired size, use Graphics.FromImage to create a Graphics object for drawing on the Bitmap, then use the DrawImage method to draw the original image onto the Bitmap.

Dim image As New System.Drawing.Bitmap(tnWidth, tnHeight);
Dim gr As System.Drawing.Graphics = System.Drawing.Graphics.FromImage(image);
gr.DrawImage(img, 0, 0, tnWidth, tnHeight);
gr.Dispose()
image.Save(destpath, ImageFormat.Jpeg)
image.Dispose()

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Author Comment

by:gogetsome
ID: 20412524
Thanks GreenGhost! That sounds like what I'm looking for. Have a tough time converting to VB.
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