Bitmap Image Too Large

Posted on 2010-08-20
Last Modified: 2012-06-27
I have code that add a company logo as a water mark to photos and then saves them back as a jpg.  Original images are 35kb, but the new image is 600kb.  The watermark is 3kb.  1) why is the new file so large?  2) How can I save these smaller?  
' Copy the foreground image into a bitmap.

        Dim phototouse As String

        phototouse = "C:\inetpub\wwwroot\watermark.png"        

        Dim picForeground As System.Drawing.Bitmap = New System.Drawing.Bitmap(phototouse)

        Dim fg_wid As Integer = picForeground.Width

        Dim fg_hgt = picForeground.Height

        Dim fg_bm As New Bitmap(fg_wid, fg_hgt)

        Using gr As Graphics = Graphics.FromImage(fg_bm)

            gr.DrawImage(picForeground, 0, 0, fg_wid, fg_hgt)

        End Using

        ' Make the red pixels transparent.


        Dim photo As String = photoname

        ' Make the result bitmap.

        Dim picBackground As System.Drawing.Bitmap = New System.Drawing.Bitmap(localfolder & photo)

        Dim bg_wid As Integer = picBackground.Width

        Dim bg_hgt = picBackground.Height

        Dim bg_bm As New Bitmap(bg_wid, bg_hgt)

        If cy = 0 And cx = 0 Then

            'Need to position photo in far left corner b/c pattern not found

            cx = 0 ' Set to zero for logo in left bottom corner, set to bg_wid - 90 for logo in bottom right corner

            cy = bg_hgt - 20


            'pattern found, adjust to cover the pattern

            cx = cx - 2

            cy = cy - 11

        End If

        Using gr As Graphics = Graphics.FromImage(bg_bm)

            gr.DrawImage(picBackground, 0, 0, bg_wid, bg_hgt)

            ' Draw the foreground image on top.

            gr.DrawImage(fg_bm, cx, cy, fg_wid, fg_hgt)

        End Using

        ' Display the result.

        Dim destfile As String = localfolder & photonewname


        ' We don't need the foreground bitmap any more.


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Question by:azyet24
  • 3

Author Comment

ID: 33490083
Attached are three images: original image, modified image and watermark

Comment by WallyMod.  Author requested the photos be removed as they contain the corporate identity.  Since the photos are not necessary for understanding of the question they have accordingly been removed.

Community Supoport Moderator

Accepted Solution

rojasc earned 500 total points
ID: 33490095
I think you are saving a bmp file in line 40 without jpeg compression

please read this page:

Author Comment

ID: 33490125
rojasc, that worked great.  50% the photo is same size as original and quality looks good. thanks.

Author Comment

ID: 33490130
Attached is the code from that rojasc suggested
Private Sub VaryQualityLevel()

        ' Get a bitmap.

        Dim bmp1 As New Bitmap("c:\TestPhoto.jpg")

        Dim jgpEncoder As ImageCodecInfo = GetEncoder(ImageFormat.Jpeg)

        ' Create an Encoder object based on the GUID

        ' for the Quality parameter category.

        Dim myEncoder As System.Drawing.Imaging.Encoder = System.Drawing.Imaging.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.

        Dim myEncoderParameters As New EncoderParameters(1)

        Dim myEncoderParameter As New EncoderParameter(myEncoder, 50&)

        myEncoderParameters.Param(0) = myEncoderParameter

        bmp1.Save("c:\TestPhotoQualityFifty.jpg", jgpEncoder, myEncoderParameters)

        myEncoderParameter = New EncoderParameter(myEncoder, 100&)

        myEncoderParameters.Param(0) = myEncoderParameter

        bmp1.Save("c:\TestPhotoQualityHundred.jpg", jgpEncoder, myEncoderParameters)

        ' Save the bitmap as a JPG file with zero quality level compression.

        myEncoderParameter = New EncoderParameter(myEncoder, 0&)

        myEncoderParameters.Param(0) = myEncoderParameter

        bmp1.Save("c:\TestPhotoQualityZero.jpg", jgpEncoder, myEncoderParameters)

    End Sub 'VaryQualityLevel


Private Function GetEncoder(ByVal format As ImageFormat) As ImageCodecInfo

    Dim codecs As ImageCodecInfo() = ImageCodecInfo.GetImageDecoders()

    Dim codec As ImageCodecInfo

    For Each codec In codecs

        If codec.FormatID = format.Guid Then

            Return codec

        End If

    Next codec

    Return Nothing

End Function

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