code that modify pixel color in an image.

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3.29/5 (4 votes)

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C#

help me to write a code that modify pixel color in an image.

Posted 15-Feb-11 19:51pm

graduate student

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Sandeep Mewara 16-Feb-11 2:08am

What kind of help? What have you tried so far?

Sergey Alexandrovich Kryukov 16-Feb-11 2:43am

Is it really that hard to just look at the help?
--SA

2 solutions

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**JF2015** · Answer 1 · 2011-02-15T19:55:00

Solution 1

Hi,

you should have a look at Christian Graus' series of articles about bitmap manipulation in C#. This shows everything that you need to know:
Image Processing for Dummies with C# and GDI+ Part 1 - Per Pixel Filters[^]

or for a very simple way to set a pixel in a pictureBox:

Bitmap bmp = (Bitmap)pictureBox1.Image;
bmp.SetPixel(5, 5, Color.White);
pictureBox1.Image = (Image)bmp;

Please note that GetPixel and SetPixel is very slow. You should have a look at Christian's article and see how he solves this issue using unsafe code.

Posted 15-Feb-11 19:55pm

JF2015

Updated 15-Feb-11 20:45pm

v3

Comments

Sergey Alexandrovich Kryukov 16-Feb-11 2:43am

Good enough, 5,
--SA
P.S. Better mention: it's slow.

JF2015 16-Feb-11 2:44am

You are right - I'll add this to my answer. That's why I mentioned CG's articles too.

Sergey Alexandrovich Kryukov 16-Feb-11 15:12pm

Thank you. I just added my own answer: fist, I noted System.Drawing of Forms is not a tag, so in principle it could be WFP, secondly, I added a reference on fast operation with System.Drawing, please see.
--SA

Sergey Alexandrovich Kryukov · Answer 2 · 2011-02-16T09:10:00

Solution 2

The answer by JF2015 is correct, buy only about System.Drawing.

As I pointed out, GetPixel/SetPixel is too slow for any
The fast operation requires lock bit technique and Marshal, see http://msdn.microsoft.com/en-us/library/5ey6h79d.aspx[^].

For WPF, fast operations are much easier; see the class System.Windows.Media.Imaging.BitmapSource and its derived classes.

—SA

Posted 16-Feb-11 9:10am

Sergey Alexandrovich Kryukov

Comments

Olivier Levrey 16-Feb-11 15:28pm

Voted 5. Nobody should use GetPixel or SetPixel (unless the image is very small maybe...)

Sergey Alexandrovich Kryukov 16-Feb-11 19:41pm

You're right. I came across rare cases when you use maybe a big picture but need to real only one "reference" picture from just one special location.

Thank you, Olivier,
--SA