直接像素访问的Opencv颜色映射

问题描述

我有一个灰度图像，我想通过用颜色调色板（如Matlab中的色彩映射）映射灰度值来显示颜色。

通过使用OpenCV cvSet2D 函数，但是我想直接访问像素的性能原因。

但是当我这样做图像有奇怪的颜色。我试图设置不同顺序的颜色（RGB，BGR，...），但似乎不能绕过它。

有我的代码：

  IplImage * temp = cvCreateImage（cvSize（img-> width / scale，img-> height / scale），IPL_DEPTH_8U，3）; 
 for（int y = 0; y< temp-> height; y ++）
 {
 uchar * ptr1 =（uchar *）（temp-> imageData + y * temp-> ; widthStep）; 
 uchar * ptr2 =（uchar *）（img-> imageData + y * img-> widthStep）; 
 
 for（int x = 0; x< temp-> width; x ++）
 {
 CvScalar v1; 
 
 int intensity =（int）ptr2 [x]; 
 int b = 0，g = 0，r = 0; 
 r = colormap [intensity] [0]; 
 g = colormap [intensity] [1]; 
 b = colormap [intensity] [2]; 
 
 if（true）
 {
 ptr1 [3 * x] = b; 
 ptr1 [3 * x + 1] = g; 
 ptr1 [3 * x + 2] = r; 
} 
 else 
 {
 v1.val [0] = r; 
 v1.val [1] = g; 
 v1.val [2] = b; 
 cvSet2D（temp，y，x，v1）; 
} 
} 
} 
  

更改if

正确的结果是使用cvSet2D：

=http://i.stack.imgur.com/RxZCe.jpgalt =在此处输入代码>

直接内存访问的错误结果：

>

感谢您的帮助

解决方案

我发布这封信

答案是：

我发现了我的错误...事实上，这是RGB，但这不是问题，我有256而不是255的颜色值...真的很抱歉...我想问问题帮助我找到了答案

谢谢

I have a gray scale image that I want to display in color by mapping the gray scale values with a color palette (like colormap in Matlab).

I managed to do it by using OpenCV cvSet2D function, but I would like to access to the pixels directly for performance reasons.

But when I do that the image has strange colors. I tried to set the colors in different orders (RGB, BGR,…) but can’t seem to get around it.

There is my code:

    IplImage* temp = cvCreateImage( cvSize(img->width/scale,img->height/scale), IPL_DEPTH_8U, 3 );
for (int y=0; y<temp->height; y++)
{
    uchar* ptr1 = (uchar*) ( temp->imageData + y * temp->widthStep );
    uchar* ptr2 = (uchar*) ( img->imageData + y * img->widthStep );

    for (int x=0; x<temp->width; x++)
    {
        CvScalar v1;

        int intensity = (int)ptr2[x];
        int b=0, g=0, r=0;
        r = colormap[intensity][0];
        g = colormap[intensity][1];
        b = colormap[intensity][2];

        if (true)
        {
            ptr1[3*x]   = b;
            ptr1[3*x+1] = g;
            ptr1[3*x+2] = r;
        }
        else
        {
            v1.val[0] = r;
            v1.val[1] = g;
            v1.val[2] = b;
            cvSet2D(temp, y, x, v1);
        }
    }
}

Change the if (true) to if (false) for different pixel access.

The correct result is with cvSet2D:

The wrong result with the direct memory access:

Thank you for your help

解决方案

I'm posting this to close the question like asked in the comments of my question.

The answer was:

I found out my error... In fact it's RGB but that wasn't the problem, I had color values at 256 instead of 255... Really sorry... I guess asking the question helped me found the answer

Thank you

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