C# Simple Image Resize : File Size Not Shrinking

Question

I have a question in regards to the code below. The code I have below successfully runs through a directory, and sets the resoultion of the picture to a smaller size. Howe

Answer 1

Not sure about bitmaps, but for other images you can specify a different compression encoder. MSDN details here

Answer 2

You need to set some of the properties on the Graphics object to change the quality of the image.

graphics.CompositingQuality = CompositingQuality.HighSpeed; 
graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphics.CompositingMode = CompositingMode.SourceCopy;
graphics.DrawImage(photo, 0, 0, width, height);

You can also set different compression encodings when saving the file or save it in a different format.

Answer 3

 private void button4_Click(object sender, EventArgs e)
  {
            String[] files;
            int count = 0;
            files = System.IO.Directory.GetFiles(@"C:/dataset");
            foreach (string file in files)
            {
            Bitmap tempBmp = new Bitmap(file);
            Bitmap bmp = new Bitmap(tempBmp, 200, 200);

            bmp.Save(
            @"C:/Newdataset1/" + count + ".jpg",
            System.Drawing.Imaging.ImageFormat.Jpeg);
            count++;
            }  

}

Answer 4

Interesting implementation detail: flip the image twice, and it will cause the thumbnail to be thrown out and this will decrease the file size.

result.RotateFlip(System.Drawing.RotateFlipType.Rotate180FlipNone); result.RotateFlip(System.Drawing.RotateFlipType.Rotate180FlipNone);

Answer 5

Found the problem. Thanks @yetapb for showing a cleaner version of the code, but that still didn't work. The answer to the problem was that I needed to explicity specify the type of file type that the image would be saved as. My guess is that because I did not specify the image format explicitly, the image compression was not handled accordingly.. A Bitmap was just saved with a smaller resolution with a '.jpg' slapped onto it, and not compressed accordingly. The following code now works.

            files = System.IO.Directory.GetFiles(@"C:\PicFolder");
            for (string file in files)
            {
            Bitmap tempBmp = new Bitmap(file);
            Bitmap bmp = new Bitmap(tempBmp, 807, 605);

            bmp.Save(
            @"C:\NewPicFolder\Pic" + count + ".jpg",
            System.Drawing.Imaging.ImageFormat.Jpeg);
            count++;
            }

Answer 6

Made a couple changes, the following code reduced file sizes as expected (for me).

private void Form1_Load(object sender, EventArgs e)
{
    string[] files = null;
    int count = 0;
    files = System.IO.Directory.GetFiles(@"C:\Users\..\..\ChristmasPicsResized");
    foreach (string file in files)
    {
        Bitmap bmp = new Bitmap( file );
        new Bitmap( bmp, 807, 605 ).Save(
                   @"C:\users\..\..\TempPicHold\Pic" + count.ToString() + ".jpg");
        count++;   
    }
}

}