Image resizing at different levels creating different size images

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I have the following code placed at a button click. Button got clicked after user selects an image to upload.

using (SD.Image OriginalImage = SD.Image.FromStream(AsyncUpload.FileContent))
        {
            decimal dRatio = (Decimal)1024 / OriginalImage.Width;
            int iScaledW = 1024;
            int iScaledH = (int)(OriginalImage.Height * dRatio);
            using (SD.Bitmap bmp = new SD.Bitmap(iScaledW, iScaledH))
            {
                bmp.SetResolution(OriginalImage.HorizontalResolution, OriginalImage.VerticalResolution);
                using (SD.Graphics Graphic = SD.Graphics.FromImage(bmp))
                {
                    Graphic.SmoothingMode =SD2.SmoothingMode.AntiAlias;
                    Graphic.InterpolationMode = SD2.InterpolationMode.HighQualityBicubic;
                    Graphic.PixelOffsetMode = SD2.PixelOffsetMode.HighQuality;
                    Graphic.FillRectangle(SD.Brushes.White, 0, 0, iScaledW, iScaledH);
                    Graphic.DrawImage(OriginalImage, 0, 0, iScaledW, iScaledH);
                    bmp.Save(Path.Combine(Server.MapPath(upPath), AsyncUpload.FileName));
                }
            }
        }

Here AsyncUpload is the name of FileUpload control. Original image is 3.96MB and by re-sizing the image with the above function, creates a re-sized image of 1.92MB.

However, If I select that same 3.96MB file as click a button that executes the following code that simply uploads whatever provided.

objfile.SaveAs(Path.Combine(Server.MapPath(upPath), AsyncUpload.FileName));

And then click a button that do the same processing of re-sizing the image as above mentioned, it creates an image of 200KB only. Below is the code of that button click.

static byte[] Crop(string Img, int Width, int Height, int X, int Y)
    {
        int w = Width;
        int h = Height;
        int xx = X;
        int yy = Y;

        try
        {
            using (SD.Image OriginalImage = SD.Image.FromFile(Img))
            {
                if (w == 0 || h == 0)
                {
                    w = OriginalImage.Width;
                    h = OriginalImage.Height;
                }

                int iScaleX = 0, iScaleY = 0;
                GetImageResolution(w, h, out iScaleX, out iScaleY);
                using (SD.Bitmap bmp = new SD.Bitmap(iScaleX, iScaleY))
                {
                    bmp.SetResolution(OriginalImage.HorizontalResolution, OriginalImage.VerticalResolution);
                    using (SD.Graphics Graphic = SD.Graphics.FromImage(bmp))
                    {
                        Graphic.SmoothingMode = SmoothingMode.AntiAlias;
                        Graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
                        Graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
                        Graphic.FillRectangle(SD.Brushes.White, 0, 0, iScaleX, iScaleY);
                        Graphic.DrawImage(OriginalImage, 0, 0, iScaleX, iScaleY);
                        bmp.Save(<Path>);
                    }

                }

            }

        }
        catch (Exception Ex)
        {
            return null;
            //  throw (Ex);
        }

    }

Both the code are same but the output images are of different sizes and that too, a big difference in size. Please help me understand why is this behavior. I want to avoid uploading big size image by reading them as stream and re-sizing them before even uploading them to disk. But the size after re-sizing is too big to accept.

Also, if anybody can share their thoughts of how to compress and image.

Thanks in advance

asked 1 min ago

user2861226

31

Image resizing at different levels creating different size images