在没有其他库的情况下用纯c / c ++编写BMP图像
问题描述 投票：38回答：9
在我的算法中，我需要创建信息输出。我必须在bmp文件中写入布尔矩阵。它必须是单色图像，如果此元素上的矩阵为真，则像素为白色。主要问题是bmp标头以及如何写这个。
9个回答
21
投票
投票
如果不使用任何其他库，您可以查看BMP file format。我过去已经实现了它，它可以在没有太多工作的情况下完成。
位图文件结构
每个位图文件包含位图文件头，位图信息头，颜色表和定义位图位的字节数组。该文件具有以下形式：
BITMAPFILEHEADER bmfh; BITMAPINFOHEADER bmih; RGBQUAD aColors []; BYTE aBitmapBits [];
...有关详细信息，请参阅文件格式
50
投票
投票
看看这是否适合你...在这段代码中，我有3个二维数组，称为红色，绿色和蓝色。每个都有[宽度] [高度]，每个元素对应一个像素 - 我希望这是有道理的！
FILE *f;
unsigned char *img = NULL;
int filesize = 54 + 3*w*h; //w is your image width, h is image height, both int
img = (unsigned char *)malloc(3*w*h);
memset(img,0,3*w*h);
for(int i=0; i<w; i++)
{
for(int j=0; j<h; j++)
{
x=i; y=(h-1)-j;
r = red[i][j]*255;
g = green[i][j]*255;
b = blue[i][j]*255;
if (r > 255) r=255;
if (g > 255) g=255;
if (b > 255) b=255;
img[(x+y*w)*3+2] = (unsigned char)(r);
img[(x+y*w)*3+1] = (unsigned char)(g);
img[(x+y*w)*3+0] = (unsigned char)(b);
}
}
unsigned char bmpfileheader[14] = {'B','M', 0,0,0,0, 0,0, 0,0, 54,0,0,0};
unsigned char bmpinfoheader[40] = {40,0,0,0, 0,0,0,0, 0,0,0,0, 1,0, 24,0};
unsigned char bmppad[3] = {0,0,0};
bmpfileheader[ 2] = (unsigned char)(filesize );
bmpfileheader[ 3] = (unsigned char)(filesize>> 8);
bmpfileheader[ 4] = (unsigned char)(filesize>>16);
bmpfileheader[ 5] = (unsigned char)(filesize>>24);
bmpinfoheader[ 4] = (unsigned char)( w );
bmpinfoheader[ 5] = (unsigned char)( w>> 8);
bmpinfoheader[ 6] = (unsigned char)( w>>16);
bmpinfoheader[ 7] = (unsigned char)( w>>24);
bmpinfoheader[ 8] = (unsigned char)( h );
bmpinfoheader[ 9] = (unsigned char)( h>> 8);
bmpinfoheader[10] = (unsigned char)( h>>16);
bmpinfoheader[11] = (unsigned char)( h>>24);
f = fopen("img.bmp","wb");
fwrite(bmpfileheader,1,14,f);
fwrite(bmpinfoheader,1,40,f);
for(int i=0; i<h; i++)
{
fwrite(img+(w*(h-i-1)*3),3,w,f);
fwrite(bmppad,1,(4-(w*3)%4)%4,f);
}
free(img);
fclose(f);
9
投票
投票
这是我所知道的最好的低级别例子，由Evercat编写。从https://en.wikipedia.org/wiki/User:Evercat/Buddhabrot.c复制
void drawbmp (char * filename) {
unsigned int headers[13];
FILE * outfile;
int extrabytes;
int paddedsize;
int x; int y; int n;
int red, green, blue;
extrabytes = 4 - ((WIDTH * 3) % 4); // How many bytes of padding to add to each
// horizontal line - the size of which must
// be a multiple of 4 bytes.
if (extrabytes == 4)
extrabytes = 0;
paddedsize = ((WIDTH * 3) + extrabytes) * HEIGHT;
// Headers...
// Note that the "BM" identifier in bytes 0 and 1 is NOT included in these "headers".
headers[0] = paddedsize + 54; // bfSize (whole file size)
headers[1] = 0; // bfReserved (both)
headers[2] = 54; // bfOffbits
headers[3] = 40; // biSize
headers[4] = WIDTH; // biWidth
headers[5] = HEIGHT; // biHeight
// Would have biPlanes and biBitCount in position 6, but they're shorts.
// It's easier to write them out separately (see below) than pretend
// they're a single int, especially with endian issues...
headers[7] = 0; // biCompression
headers[8] = paddedsize; // biSizeImage
headers[9] = 0; // biXPelsPerMeter
headers[10] = 0; // biYPelsPerMeter
headers[11] = 0; // biClrUsed
headers[12] = 0; // biClrImportant
outfile = fopen(filename, "wb");
//
// Headers begin...
// When printing ints and shorts, we write out 1 character at a time to avoid endian issues.
//
fprintf(outfile, "BM");
for (n = 0; n <= 5; n++)
{
fprintf(outfile, "%c", headers[n] & 0x000000FF);
fprintf(outfile, "%c", (headers[n] & 0x0000FF00) >> 8);
fprintf(outfile, "%c", (headers[n] & 0x00FF0000) >> 16);
fprintf(outfile, "%c", (headers[n] & (unsigned int) 0xFF000000) >> 24);
}
// These next 4 characters are for the biPlanes and biBitCount fields.
fprintf(outfile, "%c", 1);
fprintf(outfile, "%c", 0);
fprintf(outfile, "%c", 24);
fprintf(outfile, "%c", 0);
for (n = 7; n <= 12; n++)
{
fprintf(outfile, "%c", headers[n] & 0x000000FF);
fprintf(outfile, "%c", (headers[n] & 0x0000FF00) >> 8);
fprintf(outfile, "%c", (headers[n] & 0x00FF0000) >> 16);
fprintf(outfile, "%c", (headers[n] & (unsigned int) 0xFF000000) >> 24);
}
//
// Headers done, now write the data...
//
for (y = HEIGHT - 1; y >= 0; y--) // BMP image format is written from bottom to top...
{
for (x = 0; x <= WIDTH - 1; x++)
{
red = reduce(redcount[x][y] + COLOUR_OFFSET) * red_multiplier;
green = reduce(greencount[x][y] + COLOUR_OFFSET) * green_multiplier;
blue = reduce(bluecount[x][y] + COLOUR_OFFSET) * blue_multiplier;
if (red > 255) red = 255; if (red < 0) red = 0;
if (green > 255) green = 255; if (green < 0) green = 0;
if (blue > 255) blue = 255; if (blue < 0) blue = 0;
// Also, it's written in (b,g,r) format...
fprintf(outfile, "%c", blue);
fprintf(outfile, "%c", green);
fprintf(outfile, "%c", red);
}
if (extrabytes) // See above - BMP lines must be of lengths divisible by 4.
{
for (n = 1; n <= extrabytes; n++)
{
fprintf(outfile, "%c", 0);
}
}
}
fclose(outfile);
return;
}
drawbmp(filename);
7
投票
投票
请注意，这些行从下到上保存，而不是相反。
此外，扫描线的字节长度必须为四的倍数，您应该在行的末尾插入填充字节以确保这一点。
6
投票
投票
这是一个适合我的代码的C ++变体。注意我必须更改大小计算以考虑行填充。
// mimeType = "image/bmp";
unsigned char file[14] = {
'B','M', // magic
0,0,0,0, // size in bytes
0,0, // app data
0,0, // app data
40+14,0,0,0 // start of data offset
};
unsigned char info[40] = {
40,0,0,0, // info hd size
0,0,0,0, // width
0,0,0,0, // heigth
1,0, // number color planes
24,0, // bits per pixel
0,0,0,0, // compression is none
0,0,0,0, // image bits size
0x13,0x0B,0,0, // horz resoluition in pixel / m
0x13,0x0B,0,0, // vert resolutions (0x03C3 = 96 dpi, 0x0B13 = 72 dpi)
0,0,0,0, // #colors in pallete
0,0,0,0, // #important colors
};
int w=waterfallWidth;
int h=waterfallHeight;
int padSize = (4-(w*3)%4)%4;
int sizeData = w*h*3 + h*padSize;
int sizeAll = sizeData + sizeof(file) + sizeof(info);
file[ 2] = (unsigned char)( sizeAll );
file[ 3] = (unsigned char)( sizeAll>> 8);
file[ 4] = (unsigned char)( sizeAll>>16);
file[ 5] = (unsigned char)( sizeAll>>24);
info[ 4] = (unsigned char)( w );
info[ 5] = (unsigned char)( w>> 8);
info[ 6] = (unsigned char)( w>>16);
info[ 7] = (unsigned char)( w>>24);
info[ 8] = (unsigned char)( h );
info[ 9] = (unsigned char)( h>> 8);
info[10] = (unsigned char)( h>>16);
info[11] = (unsigned char)( h>>24);
info[20] = (unsigned char)( sizeData );
info[21] = (unsigned char)( sizeData>> 8);
info[22] = (unsigned char)( sizeData>>16);
info[23] = (unsigned char)( sizeData>>24);
stream.write( (char*)file, sizeof(file) );
stream.write( (char*)info, sizeof(info) );
unsigned char pad[3] = {0,0,0};
for ( int y=0; y<h; y++ )
{
for ( int x=0; x<w; x++ )
{
long red = lround( 255.0 * waterfall[x][y] );
if ( red < 0 ) red=0;
if ( red > 255 ) red=255;
long green = red;
long blue = red;
unsigned char pixel[3];
pixel[0] = blue;
pixel[1] = green;
pixel[2] = red;
stream.write( (char*)pixel, 3 );
}
stream.write( (char*)pad, padSize );
}
6
投票
投票
Clean C Code for Bitmap (BMP) Image Generation
生成的图像：
代码不使用除stdio.h之外的任何库。因此，代码可以很容易地结合到C-Family的其他语言中，如C ++，C＃，Java。
#include <stdio.h>
const int bytesPerPixel = 3; /// red, green, blue
const int fileHeaderSize = 14;
const int infoHeaderSize = 40;
void generateBitmapImage(unsigned char *image, int height, int width, char* imageFileName);
unsigned char* createBitmapFileHeader(int height, int width, int paddingSize);
unsigned char* createBitmapInfoHeader(int height, int width);
int main(){
int height = 341;
int width = 753;
unsigned char image[height][width][bytesPerPixel];
char* imageFileName = "bitmapImage.bmp";
int i, j;
for(i=0; i<height; i++){
for(j=0; j<width; j++){
image[i][j][2] = (unsigned char)((double)i/height*255); ///red
image[i][j][1] = (unsigned char)((double)j/width*255); ///green
image[i][j][0] = (unsigned char)(((double)i+j)/(height+width)*255); ///blue
}
}
generateBitmapImage((unsigned char *)image, height, width, imageFileName);
printf("Image generated!!");
}
void generateBitmapImage(unsigned char *image, int height, int width, char* imageFileName){
unsigned char padding[3] = {0, 0, 0};
int paddingSize = (4 - (width*bytesPerPixel) % 4) % 4;
unsigned char* fileHeader = createBitmapFileHeader(height, width, paddingSize);
unsigned char* infoHeader = createBitmapInfoHeader(height, width);
FILE* imageFile = fopen(imageFileName, "wb");
fwrite(fileHeader, 1, fileHeaderSize, imageFile);
fwrite(infoHeader, 1, infoHeaderSize, imageFile);
int i;
for(i=0; i<height; i++){
fwrite(image+(i*width*bytesPerPixel), bytesPerPixel, width, imageFile);
fwrite(padding, 1, paddingSize, imageFile);
}
fclose(imageFile);
}
unsigned char* createBitmapFileHeader(int height, int width, int paddingSize){
int fileSize = fileHeaderSize + infoHeaderSize + (bytesPerPixel*width+paddingSize) * height;
static unsigned char fileHeader[] = {
0,0, /// signature
0,0,0,0, /// image file size in bytes
0,0,0,0, /// reserved
0,0,0,0, /// start of pixel array
};
fileHeader[ 0] = (unsigned char)('B');
fileHeader[ 1] = (unsigned char)('M');
fileHeader[ 2] = (unsigned char)(fileSize );
fileHeader[ 3] = (unsigned char)(fileSize>> 8);
fileHeader[ 4] = (unsigned char)(fileSize>>16);
fileHeader[ 5] = (unsigned char)(fileSize>>24);
fileHeader[10] = (unsigned char)(fileHeaderSize + infoHeaderSize);
return fileHeader;
}
unsigned char* createBitmapInfoHeader(int height, int width){
static unsigned char infoHeader[] = {
0,0,0,0, /// header size
0,0,0,0, /// image width
0,0,0,0, /// image height
0,0, /// number of color planes
0,0, /// bits per pixel
0,0,0,0, /// compression
0,0,0,0, /// image size
0,0,0,0, /// horizontal resolution
0,0,0,0, /// vertical resolution
0,0,0,0, /// colors in color table
0,0,0,0, /// important color count
};
infoHeader[ 0] = (unsigned char)(infoHeaderSize);
infoHeader[ 4] = (unsigned char)(width );
infoHeader[ 5] = (unsigned char)(width>> 8);
infoHeader[ 6] = (unsigned char)(width>>16);
infoHeader[ 7] = (unsigned char)(width>>24);
infoHeader[ 8] = (unsigned char)(height );
infoHeader[ 9] = (unsigned char)(height>> 8);
infoHeader[10] = (unsigned char)(height>>16);
infoHeader[11] = (unsigned char)(height>>24);
infoHeader[12] = (unsigned char)(1);
infoHeader[14] = (unsigned char)(bytesPerPixel*8);
return infoHeader;
}
3
投票
投票
我编辑了ralf的htp代码，以便编译（在gcc上运行ubuntu 16.04 lts）。这只是初始化变量的问题。
int w = 100; /* Put here what ever width you want */
int h = 100; /* Put here what ever height you want */
int red[w][h];
int green[w][h];
int blue[w][h];
FILE *f;
unsigned char *img = NULL;
int filesize = 54 + 3*w*h; //w is your image width, h is image height, both int
if( img )
free( img );
img = (unsigned char *)malloc(3*w*h);
memset(img,0,sizeof(img));
int x;
int y;
int r;
int g;
int b;
for(int i=0; i<w; i++)
{
for(int j=0; j<h; j++)
{
x=i; y=(h-1)-j;
r = red[i][j]*255;
g = green[i][j]*255;
b = blue[i][j]*255;
if (r > 255) r=255;
if (g > 255) g=255;
if (b > 255) b=255;
img[(x+y*w)*3+2] = (unsigned char)(r);
img[(x+y*w)*3+1] = (unsigned char)(g);
img[(x+y*w)*3+0] = (unsigned char)(b);
}
}
unsigned char bmpfileheader[14] = {'B','M', 0,0,0,0, 0,0, 0,0, 54,0,0,0};
unsigned char bmpinfoheader[40] = {40,0,0,0, 0,0,0,0, 0,0,0,0, 1,0, 24,0};
unsigned char bmppad[3] = {0,0,0};
bmpfileheader[ 2] = (unsigned char)(filesize );
bmpfileheader[ 3] = (unsigned char)(filesize>> 8);
bmpfileheader[ 4] = (unsigned char)(filesize>>16);
bmpfileheader[ 5] = (unsigned char)(filesize>>24);
bmpinfoheader[ 4] = (unsigned char)( w );
bmpinfoheader[ 5] = (unsigned char)( w>> 8);
bmpinfoheader[ 6] = (unsigned char)( w>>16);
bmpinfoheader[ 7] = (unsigned char)( w>>24);
bmpinfoheader[ 8] = (unsigned char)( h );
bmpinfoheader[ 9] = (unsigned char)( h>> 8);
bmpinfoheader[10] = (unsigned char)( h>>16);
bmpinfoheader[11] = (unsigned char)( h>>24);
f = fopen("img.bmp","wb");
fwrite(bmpfileheader,1,14,f);
fwrite(bmpinfoheader,1,40,f);
for(int i=0; i<h; i++)
{
fwrite(img+(w*(h-i-1)*3),3,w,f);
fwrite(bmppad,1,(4-(w*3)%4)%4,f);
}
fclose(f);
1
投票
投票
如果使用上述C ++函数在图像中间获得奇怪的颜色切换。一定要以二进制模式打开流出：imgFile.open(filename, std::ios_base::out | std::ios_base::binary);
否则，Windows会在文件中间插入不需要的字符！ （几个小时以来我一直在讨论这个问题）
0
投票
投票
我只是想分享Minhas Kamal代码的改进版本，因为尽管它对大多数应用程序都运行良好，但我仍然遇到了一些问题。要记住的两件非常重要的事情：
- 代码（在编写本文时）在两个静态数组上调用free（）。这将导致程序崩溃。所以我评论了那些线。
- 绝对假设您的像素数据的音高始终为（Width * BytesPerPixel）。最好让用户指定音高值。示例：在Direct3D中操作资源时，RowPitch永远不能保证是所使用的字节深度的偶数倍。这可能会导致生成的位图出错（特别是在奇数分辨率，如1366x768）。
在下面，您可以看到我对其代码的修订：
const int bytesPerPixel = 4; /// red, green, blue
const int fileHeaderSize = 14;
const int infoHeaderSize = 40;
void generateBitmapImage(unsigned char *image, int height, int width, int pitch, const char* imageFileName);
unsigned char* createBitmapFileHeader(int height, int width, int pitch, int paddingSize);
unsigned char* createBitmapInfoHeader(int height, int width);
void generateBitmapImage(unsigned char *image, int height, int width, int pitch, const char* imageFileName) {
unsigned char padding[3] = { 0, 0, 0 };
int paddingSize = (4 - (/*width*bytesPerPixel*/ pitch) % 4) % 4;
unsigned char* fileHeader = createBitmapFileHeader(height, width, pitch, paddingSize);
unsigned char* infoHeader = createBitmapInfoHeader(height, width);
FILE* imageFile = fopen(imageFileName, "wb");
fwrite(fileHeader, 1, fileHeaderSize, imageFile);
fwrite(infoHeader, 1, infoHeaderSize, imageFile);
int i;
for (i = 0; i < height; i++) {
fwrite(image + (i*pitch /*width*bytesPerPixel*/), bytesPerPixel, width, imageFile);
fwrite(padding, 1, paddingSize, imageFile);
}
fclose(imageFile);
//free(fileHeader);
//free(infoHeader);
}
unsigned char* createBitmapFileHeader(int height, int width, int pitch, int paddingSize) {
int fileSize = fileHeaderSize + infoHeaderSize + (/*bytesPerPixel*width*/pitch + paddingSize) * height;
static unsigned char fileHeader[] = {
0,0, /// signature
0,0,0,0, /// image file size in bytes
0,0,0,0, /// reserved
0,0,0,0, /// start of pixel array
};
fileHeader[0] = (unsigned char)('B');
fileHeader[1] = (unsigned char)('M');
fileHeader[2] = (unsigned char)(fileSize);
fileHeader[3] = (unsigned char)(fileSize >> 8);
fileHeader[4] = (unsigned char)(fileSize >> 16);
fileHeader[5] = (unsigned char)(fileSize >> 24);
fileHeader[10] = (unsigned char)(fileHeaderSize + infoHeaderSize);
return fileHeader;
}
unsigned char* createBitmapInfoHeader(int height, int width) {
static unsigned char infoHeader[] = {
0,0,0,0, /// header size
0,0,0,0, /// image width
0,0,0,0, /// image height
0,0, /// number of color planes
0,0, /// bits per pixel
0,0,0,0, /// compression
0,0,0,0, /// image size
0,0,0,0, /// horizontal resolution
0,0,0,0, /// vertical resolution
0,0,0,0, /// colors in color table
0,0,0,0, /// important color count
};
infoHeader[0] = (unsigned char)(infoHeaderSize);
infoHeader[4] = (unsigned char)(width);
infoHeader[5] = (unsigned char)(width >> 8);
infoHeader[6] = (unsigned char)(width >> 16);
infoHeader[7] = (unsigned char)(width >> 24);
infoHeader[8] = (unsigned char)(height);
infoHeader[9] = (unsigned char)(height >> 8);
infoHeader[10] = (unsigned char)(height >> 16);
infoHeader[11] = (unsigned char)(height >> 24);
infoHeader[12] = (unsigned char)(1);
infoHeader[14] = (unsigned char)(bytesPerPixel * 8);
return infoHeader;
}
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