如何产生对比鲜明的彩色图像? [英] how produce color contrast stretched image?

问题描述

我在一个站点上找到了一个灰度对比拉伸图像的公式，对其进行了编码和完成.但是任何人都可以对其进行编辑以得到彩色对比度拉伸图像吗?

i found a formula on a site for grey contrast stretched image, i code it and its done. but can any one edit it for color contrast stretched image?

CBitmap img;
  CDC dc;
  BITMAP bmp;
  img.LoadBitmapW(IDB_BIT);
  img.GetBitmap(&bmp);
  CDC* pDC = this->GetDC();
  dc.CreateCompatibleDC(pDC);
  CBitmap* pOld = dc.SelectObject(&img);
  for(int y = 0; y < bmp.bmHeight; y++)
  {
      for(int x = 0; x < bmp.bmWidth; x++)
      {
          COLORREF rgb = dc.GetPixel(x, y);
          BYTE r = GetRValue(rgb);
          BYTE g = GetGValue(rgb);
          BYTE b = GetBValue(rgb);
          BYTE bw = (BYTE)(0.3 * r + 0.59 * g + 0.11 * b + 0.5);
          if(min>bw)
             min=bw;
          if(max<bw)
             max=bw;
      }
  }
  for(int y = 0; y < bmp.bmHeight; y++)
  {
      for(int x = 0; x < bmp.bmWidth; x++)
      {
          COLORREF rgb = dc.GetPixel(x, y);
          BYTE r = GetRValue(rgb);
          BYTE g = GetGValue(rgb);
          BYTE b = GetBValue(rgb);
          BYTE bw = (RGB(r,g,b)-min);
          bw=bw*(255/(max-min));
          bw+=max;
          dc.SetPixel(x, y, RGB(bw, bw, bw));
      }
  }
  pDC->BitBlt(200, 50, bmp.bmWidth, bmp.bmHeight, &dc, 0, 0, SRCCOPY);
  dc.SelectObject(pOld);

推荐答案

您发布的算法下面的思想如下:

The idea beneath the algorithm you have posted is the following:

1. 将位图转换为灰度
2. 从整个位图获取最小和最大灰度级
3. 重新映射每个灰度，以便将原始范围 [min，max] 线性映射到 [0，255]

1. convert the bitmap to grayscale
2. get the minimum and maximum gray levels from the whole bitmap
3. remap each gray level so that the original range [min, max] is mapped linearly to [0, 255]

要将算法扩展为彩色图像，您可以按照以下步骤进行操作:

To extend the algorithm to color images you can work as follow:

for(int y = 0; y < bmp.bmHeight; y++)
{
   for(int x = 0; x < bmp.bmWidth; x++)
   {
      COLORREF rgb = dc.GetPixel(x, y);
      BYTE r = GetRValue(rgb);
      BYTE g = GetGValue(rgb);
      BYTE b = GetBValue(rgb);
      if (min > r) min = r;
      if (min > g) min = g;
      if (min > b) min = b;
      if (max < r) max = r;
      if (max < g) max = g;
      if (max < b) max = b;
   }
}
for(int y = 0; y < bmp.bmHeight; y++)
{
   for(int x = 0; x < bmp.bmWidth; x++)
   {
      COLORREF rgb = dc.GetPixel(x, y);
      BYTE r = (GetRValue(rgb) - min) * 255 / (max - min);
      BYTE g = (GetGValue(rgb) - min) * 255 / (max - min);
      BYTE b = (GetBValue(rgb) - min) * 255 / (max - min);
      dc.SetPixel(x, y, RGB(r, g, b));
   }
}

我建​​议您不要使用CDC.GetPixel，因为它非常慢且效率低下.您具有CBitmap类，GetBitmapBits和SetBitmapBits方法.请访问以下网址，以获取有关图像编辑的更多信息 http://en.wikipedia.org/wiki/Image_editing [^ ].

I would recommend you NOT to use CDC.GetPixel because it''s very slow and inefficient.You have CBitmap class and GetBitmapBits and SetBitmapBits methods.Please visit the following url for more information of images editing http://en.wikipedia.org/wiki/Image_editing[^].

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