1. Magick.NET
By Jax

2. Magick.NET ??
ImageMagick is a powerful image manipulation library that supports
over 100 major file formats (not including sub-formats). With
Magick.NET you can use ImageMagick without having to install
ImageMagick on your server or desktop.
http://magick.codeplex.com/documentation

3. Use Resize
using (var image = new MagickImage("001.png")) {
image.Resize(100, 100);
image.Write("thumb.jpg");
}

4. PNG to JPG background issue
using (var image = new MagickImage("001.png")) {
image.Resize(100, 100);
image.Extent(image.Width, image.Height, new MagickColor("#FFF"));
image.Format = MagickFormat.Jpeg;
image.Quality = 80;
image.Write("thumb.jpg");
}

5. Use Crop
using (var image = new MagickImage("001.png")) {
int size = Math.Min(image.Width, image.Height);
image.Crop(size, size, Gravity.Center);
image.Write("crop.jpg");
}
using (var image = new MagickImage("001.png")) {
image.Crop(new MagickGeometry(20, 20, 200, 200));
image.Write("crop.jpg");
}

6. Input / Output functions
public MagickImage(Bitmap bitmap);
public MagickImage(byte[] data);
public MagickImage(MagickImage image);
public MagickImage(Stream stream);
public MagickImage(string fileName);
public MagickImage(MagickColor color, int width, int height);
public string ToBase64();
public Bitmap ToBitmap();
public Bitmap ToBitmap(ImageFormat imageFormat);
public byte[] ToByteArray();
public override sealed string ToString();
public void Write(Stream stream);
public void Write(string fileName);

7. Resize functions
image.AdaptiveResize(100, 100);
// Resize using mesh interpolation. It works well for small resizes of less
// than +/- 50% of the original image size. For larger resizing on images a
// full filtered and slower resize function should be used instead.
image.Resize(100, 100);
// Resize image to specified size.
image.Sample(100, 100);
// Resize image by using pixel sampling algorithm.
image.Scale(100, 100);
// Resize image by using simple ratio algorithm.

8. 效率 (sec)
• size: 5906 x 8268 run: 100
• AdaptiveResize:
48.133
• Resize:
224.000
• Sample:
47.448
• Scale:
85.788
•
•
•
•
•
size: 2480 x 3508 run: 100
AdaptiveResize:
9.994
Resize:
36.165
Sample:
9.161
Scale:
15.153

9. Setup 注意事項
• Use NuGet
• Magick.NET-Q8-x86
• Magick.NET-Q8-x64
• Magick.NET-Q16-x86
• Magick.NET-Q16-x64
• 需要安裝
• Visual C++ Redistributable for Visual Studio 2012 Update 4

10. Q8 or Q16?
• Versions with Q8 in the name are 8 bits-per-pixel component (e.g. 8bit red, 8-bit green, etc.), whereas, Q16 are 16 bits-per-pixel
component. A Q16 version permits you to read or write 16-bit images
without losing precision but requires twice as much resources as the
Q8 version.

11. ImageMagick Command-line Tools
http://www.imagemagick.org/script/index.php
Use
convert test.png -resize 100x100 -quality 80 thumb.jpg
convert test.png -adaptive-resize 100x100 -quality 80 thumb.jpg