Picture image

I'd like to display a color image in black and white only ? What should I adjust ?
Thanks a lot

Here is a link to convert a color bitmap into monochrome.
http://support.microsoft.com/default.aspx/kb/77282

Quote:

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Originally Posted by yuenqi

I'd like to display a color image in black and white only ? What should I adjust ?
Thanks a lot

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When you say black and white, do you mean monochrome (literally only black pixel or white pixel) or do you mean greyscale (like a black and white photo)?

If the former, see _Superman_'s link. If the latter, you'll have to go through each pixel and apply a formula to the red, green, and blue components, to convert to greyscale equivalent. The mathematical formula is:

grey=0.2125*red+0.7154*green+0.0721*blue;

To do this to an image, use something like this in a loop:

Code:

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  unsigned cr,rd,gn,bl,av;

  for(;;)  //do whatever to loop through your image here
  {
    cr=GetPixel(hdc,x,y);
    rd=GetRValue(cr);
    gn=GetGValue(cr);
    bl=GetBValue(cr);
    av=(rd*2125+gn*7154+bl*721)/10000;
    SetPixel(hdc,x,y,RGB(av,av,av));
  }

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