The "Download Now" link directs you to the iTunes App Store, where you must continue the download process. You must have iTunes installed in order to open the link, and you must have an active iTunes account to download the application. This download may not be available in some countries.
From Sandy McGuffog:
Got a JPEG that you wish you could convert into raw format? Colors came out just perfect in the JPEG, but you can't recreate them from the raw image? No problem!toDNG converts very nearly any bitmap file to a DNG (Digital Negative) file quickly and easily, with colors exactly like the original. Files supported include JPEG, TIFF, GIF, PNG, most raw formats, and even icon files. Once converted to DNG, you can easily edit the converted files in Adobe applications such as Photoshop and Lightroom, or any other application that supports "linear raw" DNG files.DNG files make it far easier to manage and keep track of your files, as they allow non-destructive editing. Non-destructive editing means that your original image data is never altered; any edits you make are stored as instructions in the DNG file, meaning that you can always go back to the original. So you don't need to keep track of multiple edited versions anymore - you always have just one file that you can revert back to its original form at the click of a button.toDNG is the easiest way to convert files to DNG; all you have to do is to drag-and-drop the files you want converted onto the toDNG application, and the files are immediately converted. And toDNG always converts your files exactly as they are - there aren't any adjustments tone curves or anything else applied. And, of course, toDNG is fully color managed, so image colors are always preserved exactly as in the original.What can't toDNG do? The DNG format itself doesn't support transparency , layers or masks, so any image that uses these features may not convert exactly as you'd expect.