No, you can't open the MLB file format. The software supports the following file formats: EPS, PCX, WMF, TIFF, BMP, EMF, DIB, WPG, IMG, JPG, & PCD. There is nowhere mentioned about MLB which means it doesn't have support for this file type. You can check by yourself on the official website of the product. Visit the page, then click on Features link to expand the category. You will see the supported file types listed on the page.