Img Compression before Save() to SQL DB

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Img Compression before Save() to SQL DB

Post by htaylor » Sun Aug 30, 2009 08:56 PM

I have this working but saving to a DB over the network is very slow (30 sec) even at 72 d.p.i. unless the lowest scanner settings are selected. No matter what resolution the user scans at I want to force 8-bit grayscale at 72 d.p.i. THEN compress the file to speed things up.

Does any one have any compression code?

I have been looking but it has eluded me.

Re: Img Compression before Save() to SQL DB

Post by htaylor » Mon Aug 31, 2009 03:12 AM

For those interested I have decided not to allow user storage in the database as there is nothing to prevent the storage of illegal images. You may wish to re-think DB storage if you have a commercial application - could be bad for the Corporate image if it hit the headlines a child molester used your tools and database to store bad pictures.

Re: Img Compression before Save() to SQL DB

Post by Alex » Mon Aug 31, 2009 05:21 AM

Hello Taylor,

Here is a snippet of code that saves images to stream in PDF format:

Public Sub ScanWithUI()
    Dim mem As MemoryStream = Nothing
    VSTwain1.AppProductName = "MyTwainApplication"
    Try
        VSTwain1.StartDevice()
        VSTwain1.SelectSource()
        VSTwain1.ShowUI = true
        VTwain1.MaxImages = 1
        Dim firstImage As Boolean = True
        While VSTwain1.AcquireModal()
            If firstImage Then
                ' Create memory stream and place the first image to it
                mem = VSTwain1.GetImageAsStream(0, ImageFileFormat.PDF)
                firstImage = False
            Else
                ' Add second and next images to the stream
                VSTwain1.SaveImageToStream(0, mem, ImageFileFormat.PDF)
            End If
        End While
    Catch ex As TwainException
        MsgBox ex.Message
    Catch ex As ImagingException
        MsgBox ex.Message
    End Try
    ...
    ' Uploading stream data to server or doing something else...
    ...
End Sub

Also please read description of the SaveImageToStream method in documentation.

Best regards, Alexander

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