verify specific color from 24 bpp image in C#

Question

is it possible to detect certain color like grey or red from 24bpp image so i can extract or highlight the specific color on image provided

The answer is yes. If you gave more info, the answer could be more than yes. — leppie, Jul 05 '12 at 10:20
actually, i want to develop simple program that can detect(verify) and highlight grey color from image provided. To be more advance, if successful i want to detect road from image. — kaki, Jul 05 '12 at 13:39

score 0 · Answer 1 · edited May 23 '17 at 12:20

0

Yes, you can compare pixel values.

Following link shows How to change color of Image at runtime

How to compare,

  bmp.GetPixel(x, y) == Color.Red

edited May 23 '17 at 12:20

Community

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answered Jul 05 '12 at 10:32

Tilak

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score 0 · Answer 2 · answered Jul 07 '12 at 20:47

Like @Tilak said, you can use bitmap.GetPixel with a for loops to search the image, like this

for(int y = 0; y < b.Height; y++)
{
     for(int x = 0; x < b.Width; x++)
     {
         if(b.GetPixel(x, y) == Color.Red)
         {
              //do something
         }
     }
}

But if you want a "simpler" way, you can just use

foreach(Color c in b)
{
     if (c == Color.Red)
     {
          //do something
     }
}

But since the arbg values might not be exactly equal to Red's, do something like this:

            int pixelA = c.A;
            int pixelR = c.R;
            int pixelG = c.G;
            int pixelB = c.B;

            int searchA = Color.Red.A;
            int searchR = Color.Red.R;
            int searchG = Color.Red.G;
            int searchB = Color.Red.B;

            diffA = Math.Abs(pixelA - searchA);
            diffR = Math.Abs(pixelR - searchR);
            diffG = Math.Abs(pixelG - searchG);
            diffB = Math.Abs(pixelB - searchB);

            if (diffA < 10 && diffB < 10 && diffG < 10 && diffR < 10)
            {
                //do something                }

            if (diffA > 10 && diffA < 20 && diffR > 10 && diffR < 20 && diffG > 10 && diffG < 20 &&
                diffB > 10 && diffB < 20)
            {
                //do something                }

            if (diffA > 20 && diffA < 130 && diffR > 20 && diffR < 130 && diffG > 20 && diffG < 130 &&
                diffB > 20 && diffB < 130)
            {
                //do something
            }

            if (diffA > 130 && diffA < 240 && diffR > 130 && diffR < 240 && diffG > 130 && diffG < 240 &&
                diffB > 130 && diffB < 240)
            {
                //do something
            }

            if (diffA > 240 && diffA < 350 && diffR > 240 && diffR < 350 && diffG > 240 && diffG < 350 &&
                diffB > 240 && diffB < 350)
            {
                //do something
            }

So you can see the different degrees of the color. Hope this helps!

verify specific color from 24 bpp image in C#

2 Answers2

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