CODEWITHSUNDEEP
c#imageresizeimage-resizing
contactmatt
contactmatt

Reputation: 18600

C# Simple Image Resize : File Size Not Shrinking

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. However, the file size is not changed. For example, an image with dimensions of 2400x1800 with file size of 1.5MB will be scaled to 800x600, but the 800x600 picture will still be 1.5MB file size. I'm think I may have to explicitly compress the picture, but I'm not sure. Any ideas?

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)
            {
                System.Drawing.Bitmap bmp = System.Drawing.Bipmap.FromFile(file);

                ResizeBitmap(bmp, 807, 605).Save(
                     @"C:\users\..\..\TempPicHold\Pic" + count.ToString() + ".jpg");
                count++;
            }
        }
        public Bitmap ResizeBitmap(Bitmap b, int nWidth, int nHeight)
        {
            Bitmap result = new Bitmap(nWidth, nHeight);
            using (Graphics g = Graphics.FromImage((Image)result))
                g.DrawImage(b, 0, 0, nWidth, nHeight);
            return result;
        }

Upvotes: 3

Views: 12525

Answers (6)

Fadi
Fadi

Reputation: 2370

 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++;
            }

}

Upvotes: 0

contactmatt
contactmatt

Reputation: 18600

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++;
            }

Upvotes: 9

µBio
µBio

Reputation: 10748

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++;   
    }
}

}

Upvotes: 0

Broam
Broam

Reputation: 4648

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);

Upvotes: 0

Dan
Dan

Reputation: 17445

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.

Upvotes: 2

GrayWizardx
GrayWizardx

Reputation: 21141

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

Upvotes: 2

Related Questions