将彩色bmp转换为灰度bmp? [英] Converting color bmp to grayscale bmp?

问题描述

我正在尝试将彩色BMP文件转换为灰度BMP.输入的bmp是24位，而我这次在输出处产生的是相同的24位bmp，只是这次是灰度的.

I am trying to convert a colored BMP file to gray-scale BMP. The input bmp is 24 bit and I am producing the same 24 bit bmp at the output, only this time in gray-scale.

我正在使用的代码是

for(int x = 0; x < max; x++)
{
    int lum;
    lum = (r[x]*0.30) + (g[x]*0.59) + (b[x]*0.11);
    r[x] = lum;
    g[x] = lum;
    b[x] = lum;
}

r，g，b数组是RGB颜色分量，我将它们放在char *r,*g,*b中.

The r, g, b arrays are the RGB color components and I have them in a char *r,*g,*b.

由于某些原因，我没有得到干净的输出.我附上我在此问题上得到的输出，它不完整，并在地方包含白色和黑色区域.那么我在这里做错了什么?

For some reasons I am not getting a clean output. I am attaching the output I am getting with this question, its patchy and contains white and black areas at palces. So what am I doing wrong here?

1. 是因为计算lum时数据丢失还是在将int作为字符存储时出了什么问题?
2. 灰度bmp不能为24位吗?还是转换后我存储rgb值的方式有问题?

在此方面的任何帮助将不胜枚举.谢谢.

Any help in this will be much appriciated. Thanks.

推荐答案

这些实际上应该是unsigned char;如果char恰好在您的平台上签名，则此代码将无法满足您的期望.

These should really be unsigned char; if char happens to be signed on your platform, then this code won't do what you expect.

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