ziriax / bmp-sharp

Simple .NetStandard C# library for handling BMP files

BMP# (bmp-sharp)

Simple .NET fully managed .NetStandard C# library for handling Bitmap (BMP) files.

Description

This is simple Bitmap library that helps you wrap binary data (pixels) into BMP header for saving into file and vice versa.

It supports only 24 bits BGR and 32 bits BGRA byte arrays.

Library supports x86 (little-endian) and ARM (big-endian).

Documentation on wiki pages.

Why this library

I'm working on a library that will help me parse CIFAR 10 dataset and I wanted to simply display binary image data. Problem was that I couldn't find any .NET library that will take byte[] and with few parameters display it as image (without conversion into float or use Windows.System.Forms/WPF) so I wrote this simple library to help me out.

Also usefull for exporting [SkiaSharp] SKBitmap data (SkiaSharp doesn't supprot this Check issue #320).

var outputImage = SkiaSharp.SKBitmap.Decode( imageFile );
if (!(outputImage.BytesPerPixel == 3 || outputImage.BytesPerPixel == 4))
	throw new Exception( $"Unsupported Bits per image ({outputImage.BytesPerPixel}) for BmpSharp" );

var bitsPerPixel = outputImage.BytesPerPixel == 4 ? BmpSharp.BitsPerPixelEnum.RGBA32 : BmpSharp.BitsPerPixelEnum.RGB24;
var bmp = new BmpSharp.Bitmap( outputImage.Width, outputImage.Height, outputImage.Bytes, bitsPerPixel );
return bmp.GetBmpBytes(flipped:true);	// returns BMP File as byte[] array

Samples

In sample folder.

public static byte[] GenerateRedGreen24BitGradient() {
	var width = 256;
	var height = 256;
	var bytesPerPixel = (int) BmpSharp.BytesPerPixelEnum.RGB24;
	var framebuffer = new byte[width * height * bytesPerPixel];

	for (var row = 0; row < height; row++) {
		for (var column = 0; column < width; column++) {
			long offset = ( row * height * bytesPerPixel ) + ( column * bytesPerPixel );
			framebuffer[offset] = 0; // blue
			framebuffer[offset + 1] = (byte) column; // green
			framebuffer[offset + 2] = (byte) row; // red
		}
	}
	return framebuffer;
}
var redGreenGradient = GenerateRedGreen24BitGradient();
var redGreenGradientBitmap = new Bitmap( 256, 256, redGreenGradient, BitsPerPixelEnum.RGB24 );
System.IO.File.WriteAllBytes( $"{nameof( redGreenGradient )}.bmp", redGreenGradientBitmap.GetBmpBytes() );

Result:

Out of scope

• All different headers formats
• Image filtering
• Compression support (use PNG)
• 1/4/8 bits per pixel support (i'm open for pull requests)

History

0.2.0 Bugfixes & RGBA32 Support

• Bug fixes and Code refactoring (there are code breaking changes from version 0.1.0).
• Added RGBA (alpha channel) support (32 bits)

0.1.0 Initial release

• Added support of saving byte[] to BMP
• Should support reading/saving of little/big endian platforms (x86 / ARM)