---
title: "BMP File Format"
canonical: https://www.graphicsmill.com/docs/gm5/BMPFileFormat.htm
product: "Graphics Mill 5.5 for .NET"
---

This documentation is for the old version. [Go to the latest Graphics Mill docs](https://www.graphicsmill.com/docs/gm/)

# BMP File Format
 
BMP (Bitmap) is a standard image format mainly used on the Microsoft Windows platform. BMP images can range from black and white (1 bit per pixel) up to 32 bit color (16.7 million colors), so the bitmap image format can store both indexed and true color images. There are two main BMP formats exist: Windows bitmap formats and OS/2 bitmap format. All of these formats support RLE-type compression for 4 and 8 bits per pixel palette images.
 
## Format Name
  
BMP
 
## MIME Type
  
image/bmp
 
## File Extensions
  
\*.bmp, \*.dib.
 
## Supported Pixel Formats
  
|  Description |  Read |  Write |
| --- | --- | --- |
 |  1 bit palette-based (Windows) |  Yes |  Yes |
 |  1 bit palette-based (OS/2) |  Yes |  No |
 |  4 bit palette-based (Windows) |  Yes |  Yes |
 |  4 bit palette-based (OS/2) |  Yes |  No |
 |  8 bit palette-based (Windows) |  Yes |  Yes |
 |  8 bit palette-based (OS/2) |  Yes |  No |
 |  24 bit RGB (Windows) |  Yes |  Yes |
 |  24 bit RGB (OS/2) |  Yes |  No |
 |  32 bit RGB (Windows) |  Yes |  Yes |
 |  32 bit RGB (OS/2) |  Yes |  No |
 
## Encoder Options
  
|  Name |  Default Value |  Comments |
| --- | --- | --- |
 |  [BmpEncoderOptions.Compression](https://www.graphicsmill.com/docs/gm5/P_Aurigma_GraphicsMill_Codecs_BmpEncoderOptions_Compression.htm.md) <br> [BmpFrame.Compression](https://www.graphicsmill.com/docs/gm5/P_Aurigma_GraphicsMill_Codecs_BmpFrame_Compression.htm.md) |  [CompressionType.None](https://www.graphicsmill.com/docs/gm5/T_Aurigma_GraphicsMill_Codecs_CompressionType.htm.md) |  The compression type of the BMP file. It can be either uncompressed or use RLE compression for 4-bit and 8-bit bitmaps. |
 
## Examples
  
### Loading BMP Files
 
The simplest way to load the BMP file is to pass its name to the constructor:
 
```
Dim bitmap As New Aurigma.GraphicsMill.Bitmap("c:\Mountain.bmp")
```
 
```csharp
Aurigma.GraphicsMill.Bitmap bitmap = new Aurigma.GraphicsMill.Bitmap(@"c:\Mountain.bmp");
```
 
Alternatively, if you already have an instance of the [Bitmap](https://www.graphicsmill.com/docs/gm5/T_Aurigma_GraphicsMill_Bitmap.htm.md), you can use the [Load](https://www.graphicsmill.com/docs/gm5/O_T_Aurigma_GraphicsMill_Bitmap_Load.htm.md) method:
 
```
Dim bitmap As New Aurigma.GraphicsMill.Bitmap
bitmap.Load("c:\Mountain.bmp")
```
 
```csharp
Aurigma.GraphicsMill.Bitmap bitmap = new Aurigma.GraphicsMill.Bitmap();
bitmap.Load(@"c:\Mountain.bmp");        
```
 
### Saving BMP Files
 
This code example saves the BMP image with RLE compression:
 
```
Dim bitmap As New Aurigma.GraphicsMill.Bitmap("c:\Mountain.gif")

bitmap.Save("C:\Mountain.bmp", New Aurigma.GraphicsMill.Codecs.BmpEncoderOptions( _
    Aurigma.GraphicsMill.Codecs.CompressionType.Rle))

bitmap.Dispose()
```
 
```csharp
using (Aurigma.GraphicsMill.Bitmap bitmap = 
           new Aurigma.GraphicsMill.Bitmap(@"C:\Mountain.gif"))
{
    bitmap.Save(@"C:\Mountain.bmp", new Aurigma.GraphicsMill.Codecs.BmpEncoderOptions(
        Aurigma.GraphicsMill.Codecs.CompressionType.Rle));
}
```
 
You can also use [BmpWriter](https://www.graphicsmill.com/docs/gm5/T_Aurigma_GraphicsMill_Codecs_BmpWriter.htm.md) class instead of the [Save](https://www.graphicsmill.com/docs/gm5/O_T_Aurigma_GraphicsMill_Bitmap_Save.htm.md) method of the Bitmap. In particular it enables you to save the image asynchronously.
 
The BmpWriter class usage is demonstrated below:
 
```
Dim bitmap As New Aurigma.GraphicsMill.Bitmap("c:\Mountain.jpg")

Dim writer As New Aurigma.GraphicsMill.Codecs.BmpWriter("C:\Mountain.bmp")

Dim frame As New Aurigma.GraphicsMill.Codecs.BmpFrame( _
    Aurigma.GraphicsMill.Codecs.CompressionType.None)

frame.SetBitmap(bitmap)

bitmap.Dispose()

writer.AddFrame(frame)

frame.Dispose()

writer.Dispose()
```
 
```csharp
using (Aurigma.GraphicsMill.Bitmap bitmap = 
           new Aurigma.GraphicsMill.Bitmap(@"c:\Mountain.jpg"))
{
    using (Aurigma.GraphicsMill.Codecs.BmpWriter writer = 
        new Aurigma.GraphicsMill.Codecs.BmpWriter())
    {
        writer.Open(@"C:\Mountain.bmp");

        using (Aurigma.GraphicsMill.Codecs.BmpFrame frame = 
                   new Aurigma.GraphicsMill.Codecs.BmpFrame())
        {
            frame.Compression = Aurigma.GraphicsMill.Codecs.CompressionType.None;
            frame.SetBitmap(bitmap);

            writer.AddFrame(frame);
        }
    }
}
```