java读取bmp图片像素数据_读取bmp文件的像素值

How can I read the color value of 24bit BMP images at all the pixel [h*w] in C or C++ on Windows [better without any 3rd party library]. I got Dev-C++

A working code will be really appreciated as I've never worked on Image reading & have come to SO after Googling [if you can google better than me, plz provide a link].

解决方案

You can try this one:

unsigned char* readBMP(char* filename)

{

int i;

FILE* f = fopen(filename, "rb");

unsigned char info[54];

fread(info, sizeof(unsigned char), 54, f); // read the 54-byte header

// extract image height and width from header

int width = *(int*)&info[18];

int height = *(int*)&info[22];

int size = 3 * width * height;

unsigned char* data = new unsigned char[size]; // allocate 3 bytes per pixel

fread(data, sizeof(unsigned char), size, f); // read the rest of the data at once

fclose(f);

for(i = 0; i < size; i += 3)

{

unsigned char tmp = data[i];

data[i] = data[i+2];

data[i+2] = tmp;

}

return data;

}

Now data should contain the (R, G, B) values of the pixels. The color of pixel (i, j) is stored at data[j * width + i], data[j * width + i + 1] and data[j * width + i + 2].

In the last part, the swap between every first and third pixel is done because windows stores the color values as (B, G, R) triples, not (R, G, B).