GDI+ FAQ: Creating Images in memory

GDI+ FAQ: Creating images from files

Creating a new blank image is accomplished with the Bitmap constructor.

[C#]

Bitmap myImage = new Bitmap(<xsize>,<ysize>);

[VB]

Dim MyImage = new Bitmap(<xsize>,<ysize>)

This method creates an image with the default color depth parameters. To specify a color depth, you can also specify a pixel format parameter in the constructor.

[C#]

Bitmap myImage = new Bitmap(<xsize>,<ysize>,PixelFormat.<format>);

[VB]

Dim MyImage = new Bitmap(<xsize>,<ysize>,PixelFormat.<format>)

Note that indexed color images, for example 8 bits per pixel with a color palette may not be created in this way. An exception will be thrown and the image will be null or Nothing. This is either a bug or an intended shortcoming.

The Pixel Formats valid for the creation of a bitmap image are:

Format16bppArgb1555

Format16bppGrayScale

Format16bppRgb555

Format16bppRgb565

Format24bppRgb

Format32bppArgb

Format32bppPArgb

Format32bppRgb

Format48bppRgb

Format64bppArgb

Format64bppPArgb

When created, the images memory area is cleared to 0. This means that images may appear black and be completely transparent if the image is one capable of storing per-pixel alpha values.

Images may be loaded from disc in any of the standard formats (JPEG, GIF, TIFF or Windows Bitmap)

This is performed with the Image static or shared method Image.FromFile

[C#]

Bitmap bm = (Bitmap)Image.FromFile("<filename>");

[VB]

Dim bm as Bitmap = CType(Image.FromFile("<filename">),Bitmap)

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