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Creating monochrome BMP with bit set

I may need help to figure out how to submit the process below. I need to write a monochrome BMP file. The code below (its from: How to save a monochrome image as bmp in Windows C ++? ) Looks like to be able to do this. I am now fixated on how to convert, std::bitsetor preferably boost::dynamic_bitsetinto this format byte*. All my attempts so far have failed, I could not write something like an 8x8 validation pattern in BMP. The process creates a BMP and is readable in Photoshop, but the content is a mess. Therefore, any suggestions on how to solve this problem are appreciated!

Save1BppImage(byte* ImageData, const char* filename, long w, long h){

    int bitmap_dx = w; // Width of image
    int bitmap_dy = h; // Height of Image

    // create file
    std::ofstream file(filename, std::ios::binary | std::ios::trunc);
    if(!file) return;

    // save bitmap file headers
    BITMAPFILEHEADER fileHeader;
    BITMAPINFOHEADER * infoHeader;
    infoHeader = (BITMAPINFOHEADER*) malloc(sizeof(BITMAPINFOHEADER) );
    RGBQUAD bl = {0,0,0,0};  //black color
    RGBQUAD wh = {0xff,0xff,0xff,0xff}; // white color


    fileHeader.bfType      = 0x4d42;
    fileHeader.bfSize      = 0;
    fileHeader.bfReserved1 = 0;
    fileHeader.bfReserved2 = 0;
    fileHeader.bfOffBits   = sizeof(BITMAPFILEHEADER) + (sizeof(BITMAPINFOHEADER));

    infoHeader->biSize          = (sizeof(BITMAPINFOHEADER) );
    infoHeader->biWidth         = bitmap_dx;    
    infoHeader->biHeight        = bitmap_dy;
    infoHeader->biPlanes        = 1;
    infoHeader->biBitCount      = 1;
    infoHeader->biCompression   = BI_RGB; //no compression needed
    infoHeader->biSizeImage     = 0;
    infoHeader->biXPelsPerMeter = 0;
    infoHeader->biYPelsPerMeter = 0;
    infoHeader->biClrUsed       = 2;
    infoHeader->biClrImportant  = 2;

    file.write((char*)&fileHeader, sizeof(fileHeader)); //write bitmapfileheader
    file.write((char*)infoHeader, (sizeof(BITMAPINFOHEADER) )); //write bitmapinfoheader
    file.write((char*)&bl,sizeof(bl)); //write RGBQUAD for black
    file.write((char*)&wh,sizeof(wh)); //write RGBQUAD for white

    int bytes = (w/8) * h ; //for example for 32X64 image = (32/8)bytes X 64 = 256;

    file.write((const char*)ImageData, bytes);

    file.close();
}

-edit -

my naive approach was something like this

    byte test[64];
for(unsigned int i=0; i<64; ++i)
    if(i % 2)
        test[i] = 0;
    else
        test[i] = 1;

Save1BppImage(test, "C:/bitmap.bmp", 8, 8);
+4
3

, , . , .

bfOffBits .

fileHeader.bfOffBits   = sizeof(BITMAPFILEHEADER) + (sizeof(BITMAPINFOHEADER)) + 2*sizeof(RGBQUAD);

0 1 , , . , , , , .

4- . 32, .

BMP , , .

, :

int bytes_in = (w + 7) / 8;
int bytes_out = ((w + 31) / 32) * 4;
const char * zeros[4] = {0, 0, 0, 0};
for (int y = h - 1;  y >= 0;  --y)
{
    file.write(((const char *)ImageData) + (y * bytes_in), bytes_in);
    if (bytes_out != bytes_in)
        file.write(zeros, bytes_out - bytes_in);
}
+2

- ...

  • BMP. , , 4.

  • . RGB, .

  • , .

.

void createBitmap( byte * imageData, const char * filename, int width, int height )
{
    BITMAPFILEHEADER bitmapFileHeader;
    memset( &bitmapFileHeader, 0, sizeof( bitmapFileHeader ) );
    bitmapFileHeader.bfType = ( 'B' | 'M' << 8 );
    bitmapFileHeader.bfOffBits = sizeof( BITMAPFILEHEADER ) + sizeof( BITMAPINFOHEADER );
    bitmapFileHeader.bfSize = bitmapFileHeader.bfOffBits + width * height * 3;

    BITMAPINFOHEADER bitmapInfoHeader;
    memset( &bitmapInfoHeader, 0, sizeof( bitmapInfoHeader ) );
    bitmapInfoHeader.biSize = sizeof( BITMAPINFOHEADER );
    bitmapInfoHeader.biWidth = width;
    bitmapInfoHeader.biHeight = height;
    bitmapInfoHeader.biPlanes = 1;
    bitmapInfoHeader.biBitCount = 24;

    std::ofstream file( filename, std::fstream::binary );

    file.write( reinterpret_cast< char * >( &bitmapFileHeader ), sizeof( bitmapFileHeader ) );
    file.write( reinterpret_cast< char * >( &bitmapInfoHeader ), sizeof( bitmapInfoHeader ) );

    // the pixels!
    file.write( imageData, width * height * 3 );

    file.close();
}

int main( int argc, const char * argv[] )
{
    int width = 12; // multiple of 4
    int height = 12;

    byte imageData[ width * height * 3 ];

    // fill imageData the way you want, this is just a sample
    // on how to set the pixel at any specific (X,Y) position

    for ( int y = 0; y < height; ++y )
    {
        for ( int x = 0; x < width; ++x )
        {
            int pos = 3 * ( y * width + x );

            byte pixelColor = ( x == 2 && y == 2 ) ? 0x00 : 0xff;

            imageData[ pos ] = pixelColor;
            imageData[ pos + 1 ] = pixelColor;
            imageData[ pos + 2 ] = pixelColor;
        }
    }

    createBitmap( imageData, "bitmap.bmp", width, height );

    return 0;
}

X = 2, Y = 2.

BMP , Y .

( ), imageData. , myByte >> position & 1, position - , 0 7.

0

Only for the archive, below the working version. Bit storage boost is required as input pixel storage.

void bitsetToBmp(boost::dynamic_bitset<unsigned char> bitset, const char* filename, int width, int height){
//write the bitset to file as 1-bit deep bmp
//bit order 0...n equals image pixels  top left...bottom right, row by row
//the bitset must be at least the size of width*height, this is not checked

std::ofstream file(filename, std::ios::binary | std::ios::trunc);
if(!file) return;

// save bitmap file headers
BITMAPFILEHEADER fileHeader;
BITMAPINFOHEADER * infoHeader;
infoHeader = (BITMAPINFOHEADER*) malloc(sizeof(BITMAPINFOHEADER) );
RGBQUAD bl = {0,0,0,0};  //black color
RGBQUAD wh = {0xff,0xff,0xff,0xff}; // white color


fileHeader.bfType      = 0x4d42;
fileHeader.bfSize      = 0;
fileHeader.bfReserved1 = 0;
fileHeader.bfReserved2 = 0;
fileHeader.bfOffBits   = sizeof(BITMAPFILEHEADER) + (sizeof(BITMAPINFOHEADER)) + 2*sizeof(RGBQUAD); 

infoHeader->biSize          = (sizeof(BITMAPINFOHEADER) );
infoHeader->biWidth         = width;    
infoHeader->biHeight        = height;
infoHeader->biPlanes        = 1;
infoHeader->biBitCount      = 1;
infoHeader->biCompression   = BI_RGB; //no compression needed
infoHeader->biSizeImage     = 0;
infoHeader->biXPelsPerMeter = 0;
infoHeader->biYPelsPerMeter = 0;
infoHeader->biClrUsed       = 2;
infoHeader->biClrImportant  = 2;

file.write((char*)&fileHeader, sizeof(fileHeader)); //write bitmapfileheader
file.write((char*)infoHeader, (sizeof(BITMAPINFOHEADER) )); //write bitmapinfoheader
file.write((char*)&bl,sizeof(bl)); //write RGBQUAD for black
file.write((char*)&wh,sizeof(wh)); //write RGBQUAD for white

// convert the bits into bytes and write the file
int offset, numBytes = ((width + 31) / 32) * 4;
byte* bytes = (byte*) malloc(numBytes * sizeof(byte));

for(int y=height - 1; y>=0; --y){
    offset = y * width;
    memset(bytes, 0, (numBytes * sizeof(byte)));
    for(int x=0; x<width; ++x)
        if(bitset[offset++]){
            bytes[x / 8] |= 1 << (7 - x % 8);
    };
    file.write((const char *)bytes, numBytes);
};
free(bytes);
file.close();

}

I wonder if theres a simpler / faster way to put a bit in a file? All bits can instead be overloaded as an array of strings to skip the extraction of a subset.

0
source

Source: https://habr.com/ru/post/1568936/

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