bmpxx

A c++ library for reading and writing bitmap / BMP files

Why?

I needed a bmp library for another project and I couldn't find any that supported enough parts of the bmp specification. So I just wrote my own, and hopefully it will be of use to some other people as well.

If it helped you, don't forget to leave the repo a star.

Support

Decoding

• All NT (Windows NT) headers
• 1, 2, 4, 8 bit rgb palette images
• 16, 24, 32 bit rgb/rgba images
• Alpha channel
• Any sane combination of pixel masks
• Correct bit mapping using floats
• BI_RGB, BI_BITFIELDS, BI_ALPHABITFIELDS compression
• 8 bit color depth (so no 10 bit)

Encoding

• 56 byte NT header
• 24 and 32 bit rgb/rgba images
• Alpha channel
• BI_RGB, BI_BITFIELDS compression
• 8 bit color depth

Api

Functions

namespace bmpxx {

// Decodes a bmp file into either an RGB or RGBA pixel array
// Returns the width, height and channel count of the image
std::pair<std::vector<uint8_t>, BmpDesc> bmp::decode(std::vector<uint8_t> inputImage);

// Encodes an RGB or RGBA pixel array into a bmp file
// Returns the encoded bmp file
std::vector<uint8_t> bmp::encode(std::vector<uint8_t> input, BmpDesc desc);

}

Structs

struct BmpDesc
{
  int32_t width;
  int32_t height;
  uint8_t channels;
}

Example

For an example see the test program.

This program can convert between bmp and the raw rgb/rgba pixel arrays.

Helping

This library also does not support all the bmp features, so if you are missing something, feel free to submit a pull request.

License

This code is licensed under the GNU General Public License v3.0, so any changes or additions to this code will have to be made public under the same license.