Understanding Filtering Options

The Direct3DX utility library supports two type of filtering: bilinear (D3DX_FT_LINEAR) and point-sampling (D3DX_FT_POINT). For higher quality resizing and mipmap generation, choose bilinear filtering. For faster operation, choose D3DX_FT_POINT.

Note  To avoid blurring in images that have text in them, using point-sampling and disabling mipmapping may work better in some specific cases.