red color detection in image

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C#

hi all
how can i detect all red objects in an image?

Posted 27-Oct-11 23:01pm

graduate student

Updated 27-Oct-11 23:11pm

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André Kraak · Answer 1 · 2011-10-27T23:17:00

Solution 3

AForge.Net Framework[^] might be something you want to have a look at.

Posted 27-Oct-11 23:17pm

André Kraak

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Mehdi Gholam 28-Oct-11 5:21am

Nice link, 5!

OriginalGriff · Answer 2 · 2011-10-27T23:10:00

Solution 1

Well the image is made of pixels (at it's most basic) and you can get at the pixel data using the GetPixel method if you load it into a Bitmap.
That would give you a Color structure of the pixel value, which has an "R" property, which is the Red info.

C#

Bitmap b = (Bitmap) Image.FromFile(@"D:\Temp\myPic.jpg");
Color c = b.GetPixel(0, 0);
Console.WriteLine(c.R);

But be aware that many colours that have a Red component do not look red!

Posted 27-Oct-11 23:10pm

OriginalGriff

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graduate student 28-Oct-11 5:12am

thnx, but i mean all red objects

OriginalGriff 28-Oct-11 5:33am

Then I would suggest you start with Google: That is way too big a subject to answer here!
http://www.google.co.uk/search?aq=f&gcx=c&sourceid=chrome&ie=UTF-8&q=object+detection+codeproject#pq=object+detection&hl=en&sugexp=kjrmc&cp=19&gs_id=h&xhr=t&q=object+detection+c&pf=p&sclient=psy-ab&source=hp&pbx=1&oq=object+detection+c%23&aq=0b&aqi=g-b1&aql=f&gs_sm=&gs_upl=&bav=on.2,or.r_gc.r_pw.,cf.osb&fp=c84f2dae6b7ee35c&biw=1387&bih=906

Zasky · Answer 3 · 2011-10-27T23:13:00

1. Read pixel RGB colour values from your image. You don't indicate whether you are reading a displayed image or image from file so that's up to you.
2. Decide what range of RGB values you consider to be 'red'. e.g. is pink 'red' enough for you?
3. Filter all pixels for your range of 'red' RGB values.

Hint: you've put very little effort into framing this question. Consequently it's difficult to know what you're having trouble with. More effort might yield better answers.