Resize and Compress image to byte array without saving the new image

Question

The image is first resized, compressed and then saved on disk as \"Preview.jpg\" and then it is opened to convert into byte array. The code works fine but I cannot figure ou

Answer 1

That is a lot of variables to do so little. You also have a number of objects not being disposed. It will also return a valid Byte array only when the resulting byte data is less than the buffer size. It works in this case because you are resizing to 200x and reducing quality.

I didnt test if I collapsed all those variables correctly, but should be very close. More important is disposing things you create, and getting the all the Bytes for the return:

Dim jgpEncoder As ImageCodecInfo = GetEncoder(ImageFormat.Jpeg)
Dim myEncoder As System.Drawing.Imaging.Encoder = 
          System.Drawing.Imaging.Encoder.Quality
Dim myEncoderParameters As New EncoderParameters(1)
Dim myEncoderParameter As New EncoderParameter(myEncoder, 50&)
myEncoderParameters.Param(0) = myEncoderParameter

Dim imgByteArray As Byte()

Using myBitmap As New Bitmap(sourceImg)    ' i guess this is from file

    Dim aspectRatio As Double = myBitmap.Height / myBitmap.Width

    ' USING for disposable objects
    Using myThumb As New Bitmap(myBitmap, 200, 
                                CInt(Math.Round(200 * aspectRatio))),
        ms As New MemoryStream

        ' encode image to memstream
        myThumb.Save(ms, jgpEncoder, myEncoderParameters)

        ' rewind and get ALL bytes for the new image
        ms.Position = 0
        imgByteArray = ms.ToArray

    End Using
End Using           ' dispose

Return imgByteArray

Answer 2

You could save it to a stream and load it from there

    Using Str As New MemoryStream
        myThumb.Save(Str, jgpEncoder, myEncoderParameters)
        myImage = Image.FromStream(Str)
    End Using