level grays of in image with C#

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3.00/5 (1 vote)

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C#

hi, please ~~who can~~ help me to show image end her level grays of and histogram with C#?
please I need your help

Posted 29-Apr-11 8:33am

ainosy

Updated 29-Apr-11 8:41am

RaviRanjanKr

v2

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Sandeep Mewara 29-Apr-11 14:42pm

Not clear.

Sergey Alexandrovich Kryukov 29-Apr-11 15:35pm

Clear enough for me to answer, but incomplete tags forced me into double work -- please see.
--SA

ainosy 29-Apr-11 15:52pm

i try to find code VS2008 to get method to convert an image to grayscale.and also show histogram

charles henington 29-Apr-11 15:18pm

? what ? Please rephrase your question. grayscale maybe?

Sergey Alexandrovich Kryukov 29-Apr-11 15:35pm

I answered, but incomplete tags forced me into double work -- please see.
--SA

ainosy 29-Apr-11 15:52pm

yes method to convert an image to grayscale!

Sergey Alexandrovich Kryukov 29-Apr-11 15:34pm

Tag it! System.Drawing or WPF or what?! You forced me into double answer in part of access to pixel.
Note, incomplete questions can be removed.
--SA

4 solutions

Solution 2

As a complement to solution from SA, and is not an answer.

http://www.switchonthecode.com/tutorials/csharp-tutorial-convert-a-color-image-to-grayscale[^]

It seems to be a good article with more then 1 method to convert an image to grayscale.
I must say, I do not understand much about processing image/bitmap under C#, so it is a whole new world for me.

Posted 29-Apr-11 9:47am

Kim Togo

Updated 29-Apr-11 10:15am

v3

Comments

ainosy 29-Apr-11 15:49pm

u'r nice think u!

Kim Togo 29-Apr-11 16:18pm

Thank you, although it does not answer your question. See answer from SA.

Sergey Alexandrovich Kryukov 29-Apr-11 15:54pm

Kim, I want to compensate the vote of 1 with my 5. Even though it does not answer the question, it does not matter: you did not have to; I already answered the main part; and this is a nice complement, looks reasonable.
--SA

Kim Togo 29-Apr-11 16:12pm

Thanks SA. It is late night here where I live, tired and will go to bed.
OP was asking about a histogram of a image. Not about converting, edit or manipulate.

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-04-29T09:31:00

First of all, you need a gray-scale bitmap. If it is colored, you need to work with if as with a gray scale, which would create some ambiguity: there can be several equally valid methods giving slightly different results.

You need to calculate color of all pixels and classify them into several groups of brightness. The number of desired groups is a free parameter; so you can have different results depending on it. I suggest you work with the arrahys of length of 2N, where N is some integer > 1. If you need to show full non-normalized histogram (which is preferred), you should create and array of N elements and define the brightness range for each array element with zero array element accepting pixels starting from zero (black) and last element — pixels of the brightest (maximum value, typically 255, but can be something like 212 to 214 (usual range for photo cameras raw mode these days; there are also so called HDR cameras).

How to get all pixels? It you use something like GetPixel, it would be infinitely long. Here is what wrong with you answer: you should have specified if you want to use System.Drawing or WPF (or something else) — the techniques are similar but completely different.

In brief, for System.Drawing use System.Drawing.Bitmap.LockBits, see the code sample: http://msdn.microsoft.com/en-us/library/5ey6h79d.aspx[^]; for WPF, use System.Windows.Media.Imaging.BitmapSource and one of the methods CopyPixels, see http://msdn.microsoft.com/en-us/library/system.windows.media.imaging.bitmapsource.aspx[^]; you will find some code samples in the help pages on CopyPixel.

—SA

Chris Trelawny-Ross · Accepted Answer · 2011-04-29T10:57:00

As others have said, your question is not clear.

Assuming that (one of) the thing(s) you want is a histogram of the gray levels in your image, here are the things you'll need to do to get it.

I'm not going to write the code for you. I'll leave you to figure that out for yourself.

1. You need to get access to the array of pixels in the image. The .Net Bitmap object (perhaps the Image object, I don't remember) has methods that allow you to do this.

2. You need to scan the pixels across each line, for all lines, getting the byte(s) the comprise each pixel.

3. For each pixel, use the bytes to create a Color object (I assume that the image is not already a gray-scale image).

4. The .Net Color object has a GetBrightness() method. This returns a float value, which you'll want to quantize (since your histogram will have a fixed number of buckets in which to count pixels of a given brightness). Let's assume that your histogram has 256 buckets. Multiply the float by 255.99 and convert the result to an int - which will be in the range 0...255.

5. Use the int from step 4 as an index into an array of ints (which will be big enough unless you have an absolutely huge image) and add one to the value at the indexed position.

6. The array now has your histogram data, that you can use to draw lines (e.g. in a PictureBox) to visualize the histogram.

charles henington · Accepted Answer · 2011-04-29T12:20:00

I know this will get bad vote because already answered but wont be the first and wont be the last So here is a way to convert image to grayscale

C#

private Bitmap MakeGrayscale(Bitmap Bitmap)
       {
           //Declare myBitmap as a new Bitmap with the same Width & Height
           Bitmap myBitmap = new Bitmap(Bitmap.Width, Bitmap.Height);

           for (int x = 0; x < Bitmap.Width; x++)
           {
               for (int y = 0; y < Bitmap.Height; y++)
               {
                   //Get the Pixel
                   Color BitmapColor = Bitmap.GetPixel(x, y);

                   //Declare grayScale as the Grayscale Pixel
                   int grayScale = (int)((BitmapColor.R * 0.3) + (BitmapColor.G * 0.59) + (BitmapColor.B * 0.11));

                   //Declare myColor as a Grayscale Color
                   Color myColor = System.Drawing.Color.FromArgb(grayScale, grayScale, grayScale);

                   //Set the Grayscale Pixel
                   myBitmap.SetPixel(x, y, myColor);
               }
           }
           return myBitmap;
       }

level grays of in image with C#

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