Preserving Bitmap values when creating a new Bitmap from System.Drawing.Image

Question

I'm trying to create a resized image from a bitmap, set a new height/width and a new resolution and save it to PNG. I can do this either from directly A) Image.FromFile(filename) or B) New Bitmap(imageSource) to create the the A Bitmap to be passed to B. Both work okay schmokay, but A does not allow me to set a new width/height on creation (but it does allow me to preserve values with useIcm=True) and B does not allow me to preseve values.

Okay, now on to some code and examples:

1. Dim sourceBitmap As New Bitmap(imagePath & myImage1Name) <-not good at all (#1 overload). Doesn't preserve things like HorizontalResolution or PixelFormat on .Save

2. Dim sourceBitmap2 As Bitmap = Image.FromFile(imagePath & myImage1Name, True) <-not good (#5 overload). it does preserve things like HorizontalResolution or PixelFormat on .Save, but it doesn't allow me to initialize image at a new size.

3. Dim targetBitmap As New Bitmap(sourceBitmap2, newWidth, newHeight) <-not good. Even though sourceBitmap2 (see #2 above) was initialized with useIcm=True, it doesn't matter once I've passed it in as the source in targetBitmap.

Basically, I'm looking for a way to contruct a New Bitmap with both something like useIcm=True and set the width/height at the same time (Width/Height are read-only properties once it's created).

I've gone down the Graphics.DrawImage route as well and it's the same - Graphics.FromImage(sourceBitmap) does not preserve values.

Why do I need these values to be preserved? Because I need to convert these pictures to PNG (for file size) with a new resolution and keep the same physical dimensions (w/h in inches) for printing. I know the new pixel width/height needed based on the resolution values I'll pass in with .SetResolution(xDpi,yDpi) to preserve physical dimensions, so that's not the problem. The issue is things like the PixelFormatSize need to remain unchanged (yes, I've tried EncoderParameters - they don't work. I can give you the gory details if you like, but suffice it to say for now, they just don't work).

Whew, got that off my chest! Okay, anyone who really knows how all this works can help?

EDIT: Files types needed to pull in to convert to PNG: BMP, TIF, GIF, WMF, EMF.

Answer 1

What about doing something like the following code: You can Draw the Bitmap on a NEWGraphic. You can then mess with the size when you redraw it.

  Dim NewGraphic As Graphics = Nothing
        Dim OutBMP As Bitmap

        Using bmp As New Bitmap(3264, 4224)
            Try

                NewGraphic = Graphics.FromImage(bmp)
                NewGraphic.FillRectangle(New SolidBrush(Color.White), 0, 0, 3264, 4224)
                NewGraphic.InterpolationMode = Drawing2D.InterpolationMode.HighQualityBicubic
                NewGraphic.SmoothingMode = Drawing2D.SmoothingMode.HighQuality
                NewGraphic.PixelOffsetMode = Drawing2D.PixelOffsetMode.HighQuality
                NewGraphic.CompositingQuality = Drawing2D.CompositingQuality.HighQuality
                NewGraphic.TextRenderingHint = Drawing.Text.TextRenderingHint.AntiAliasGridFit

                NewGraphic.DrawImage(MetaFileToConvert, 0, 0, 3264, 4224)

                OutBMP = CType(FFConvertToBitonal(CType(bmp, Bitmap)), Bitmap)
                OutBMP.SetResolution(385, 385)

                OutImage = DirectCast(OutBMP, Image)

            Catch ex As Exception
                Throw ex
            Finally
                NewGraphic.Dispose()

            End Try

        End Using

Answer 2

Why not just do Dim targetBitmap As New Bitmap(Image.FromFile(imagePath & myImage1Name, True), newWidth, newHeight)?