You may save to either a Windows Bitmap (bmp) file, or an OGF file. The BMP format is 24 bits per pixel in Windows format. When saving to an OGF file, a new OGF file is created with the selected texture as the only one in the new file.
A new blank texture is then added with the size you selected. To fill in the texture, use the Generate Mipmap... or Replace Mipmap... commands.
To select the file to read, click the Browse button in the Replace dialog. A file dialog is displayed allowing you to choose an image file from your file system. File formats that can be read are Window Bitmap files (BMP), JPEG Files (JPEG) and GIF Files (GIF).
Transparency information is how the application works out which pixels are transparent in the loaded image. Currently, only one option exists, which loads transparency information from the file. This does not apply to Bitmaps of JPEG Files, only GIF files.
If the loaded image file has different dimensions than the texture being replaced, it has to be scaled (resized). Choose smooth to give a high quality resize, or fast for a worse-looking one. The scaling option will be disabled if no scaling is required for the loaded image.
A dialog is displayed allowing you to choose the image you want to generate the mipmap from, and the type of scaling. For type, choose Best for a high quality resize, or Fastest for a worse looking one!