C# WPF getpixel is very slow

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Hi I want to process an image in WPF
I found no way to apply getpixel function except for:

public Color GetPixel(BitmapSource bitmap, int x, int y)
{
    CroppedBitmap cb = new CroppedBitmap(bitmap, new Int32Rect(x, y, 1, 1));
    byte[] pixel = new byte[bitmap.Format.BitsPerPixel / 8];
    cb.CopyPixels(pixel, bitmap.Format.BitsPerPixel / 8, 0);
    return Color.FromRgb(pixel[2], pixel[1], pixel[0]);
}

but since this function is run inside a loop it is very slow.
is there any way to make it fast?

Posted 2-Oct-11 1:36am

cardano7

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hzawary 2-Oct-11 15:00pm

---start by copying the entire data to an array---
Oh my God, Bang's solutions will revolutionize in the Image Processing!!!
Yes, WIC dont know about this solution!!!

4 solutions

Solution 1

GetPixel is a wrapper around the GDI drawing components.
Calling the GDI methods directly[^] could help improve speed.

Posted 2-Oct-11 1:47am

Abhinav S

Updated 2-Oct-11 18:43pm

v2

Comments

cardano7 2-Oct-11 7:58am

Thanks
but WPF doesn't support many features of WinForm.
what to do with this line?
IntPtr hDC = GetDC(control.Handle);
control.Handle is not recognized

Philippe Mori 2-Oct-11 21:21pm

Help reduce speed... LOL. If speed is reduced, then it will be even slower!!!

Abhinav S 3-Oct-11 0:43am

Fixed. Thanks for that.

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Simon Bang Terkildsen · Accepted Answer · 2011-10-02T07:26:00

I suggest you take another approach instead of having a loop that calls your function, where you each and every time copy the part of your image, as this has a massive overhead.

The approach I would suggest is that you start by copying the entire data to an array, not just one pixel at a time. And then in your loop you index into your array to get the color.

The solution by hzawary I suggest you disregard, the only reason you'll ever use unsafe code would be because you had a 3rd party library which required it. And that library would then also be poorly designed so you shouldn't choose it to start with :)

Dave Kreskowiak · Accepted Answer · 2011-10-02T02:03:00

Solution 3

Search the articles for "Image processing for dummies". You'll find a series of articles that demonstrates how to access the Bitmap data directly, without using GetPixel.

Posted 2-Oct-11 2:03am

Dave Kreskowiak

hzawary · Accepted Answer · 2011-10-02T02:10:00

Solution 4

I also very research for this problem that find this link:
wpf-image-processing

Posted 2-Oct-11 2:10am

hzawary