How to speed up image resizing in C# .NET

Question

1.00/5 (1 vote)

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E.g. Resize an 8000x8000 big size image to 500x500 small size image, below C# .NET methods were tested:

1. Bitmap smallimg = new Bitmap(bigimg, 500, 500);

2. Bitmap smallimg = bigimg.GetThumbnailImage(500, 500, ...);

3. Bitmap smallimg = new Bitmap(500, 500);
Graphics.FromImage(smallimg).DrawImage(bigimg, 0, 0, 500, 500);

Above methods all cost about 400~500 milliseconds time. It is too slow.

Any method can speed up the image resizing?

Include using Intel Graphics HD 520 capacity (e.g. DirectX 12).

What I have tried:

PictureBox pb = new PictureBox();
pb.Image = bigimg; // 8000x8000 image

pb.DrawToBitmap(...) is also very slow.

Posted 31-Jan-23 16:21pm

w14243

Updated 31-Jan-23 16:54pm

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PIEBALDconsult 31-Jan-23 22:26pm

I never (or rarely) try to do anything faster than Microsoft's best can do it.

[no name] 1-Feb-23 20:57pm

You have to be more specific. Was it "load time"? Render time? Save time? Saveing or displaying? If it's for viewing, use a ViewBox. You could even save the visual from the ViewBox. Anyway, if you're "resizing" just to save, you should be batching it or doing it in the background if it's an issue (and not on the UI thread).

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Graeme_Grant · Answer 1 · 2023-01-31T16:54:00

Solution 1

See if this helps: Image Resizing - outperform GDI+ | CodeProject[^]

UPDATE #1
Try: GitHub - mono/SkiaSharp: SkiaSharp is a cross-platform 2D graphics API for .NET platforms based on Google's Skia Graphics Library. It provides a comprehensive 2D API that can be used across mobile, server and desktop models to render images.[^]

UPDATE #2

Some other 3rd-party libraries to try:
1. ImageFactory :: ImageProcessor[^]
2. GitHub - SixLabors/ImageSharp: A modern, cross-platform, 2D Graphics library for .NET[^]
3. Emgu CV: OpenCV in .NET (C#, VB, C++ and more)[^]

Posted 31-Jan-23 16:54pm

Graeme_Grant

Updated 1-Feb-23 16:53pm

v3

Comments

w14243 1-Feb-23 0:15am

Tested it, it is very very slow.

Graeme_Grant 1-Feb-23 3:12am

Have you tried any 3rd-party libs?

w14243 1-Feb-23 3:16am

Have not. I don't know any 3rd-party libs.

Graeme_Grant 1-Feb-23 3:25am

Try this: GitHub - mono/SkiaSharp: SkiaSharp is a cross-platform 2D graphics API for .NET platforms based on Google's Skia Graphics Library. It provides a comprehensive 2D API that can be used across mobile, server and desktop models to render images.[^]

w14243 1-Feb-23 22:38pm

Tested it.
SKBitmap.Resize is about 125ms, but SKBitmap.Decode is about 1000ms.

private void button2_Click(object sender, EventArgs e)
{
long t0 = Environment.TickCount64;

using (var original = SKBitmap.Decode(@"D:\y\7\y.jpg")) // 7000x9000 size image
{
long t3 = Environment.TickCount64;
long t3e = t3 - t0; // about 1000ms

using (var resized = original.Resize(new SKImageInfo(70 * 10, 90 * 10), SKFilterQuality.High))
{
long t4 = Environment.TickCount64;
long t4e = t4 - t3; // about 125ms

if (resized == null)
return;

Bitmap bmp = new Bitmap(resized.Encode(SKEncodedImageFormat.Jpeg, 100).AsStream(), false);

long t7 = Environment.TickCount64;
long t7e = t7 - t4; // about 30ms

PictureBox pb = new PictureBox();
pb.Image = bmp;
pb.SizeMode = PictureBoxSizeMode.AutoSize;
pb.Left = 0;
pb.Top = 0;
this.Controls.Add(pb);

long te = t7 - t0;

int bb = 0;
}
}

int xx = 0;
}

Graeme_Grant 1-Feb-23 22:50pm

hmmm... found a couple more free libs. Beyond that, do trials of commercial libs to see if they are any better.