The UltraISO program is one of the most powerful and functional in terms of working with images of many known types. However, this application, despite all its advantages, when opening some files, is not immune from an error with a message about an unknown image format. UltraISO, in theory, recognizes almost everything that is possible. But why then crashes like this? Let's try to figure out what this is connected with and how to fix the problem in the simplest ways.
Error in the UltraISO program "Unknown image format": causes of occurrence
Let's start, of course, by considering the reasons for this phenomenon. In the most general case, it can be noted that in a sense, this application (however, like its analogues) works somewhat similar to archiver programs, which also seem to determine the type of file associated with it and sometimes see its contents, but cannot open it. The main reasonThe fact that UltraISO gives a message about an unknown ISO image format even for registered file types is considered incorrect creation of the image initially, which in a sense resembles incorrect data packaging or problems with underloaded archives. It may very well be that the application in which the image was originally created did not exit correctly, or the image creation was not fully completed. The same can be said about downloading images from the Internet when the desired file was damaged or not completely downloaded.

It also happens that an error is thrown for unsupported formats (for example, DMG), which are designed for other operating systems other than Windows.
UltraISO: Unknown iso image format. What to do first?
Now let's look at troubleshooting. First of all, if we are talking about underloaded or damaged files, just repeat the download from another resource. Further, pay attention at that moment that, despite the icon of association of the opened object with the program present in the file manager, such a file may not always be supported by it.

In order to make sure of full support, in the same "Explorer" turn on the display of extensions or first launch the UltraISO application itself, and only then use the file opening through the appropriate menu, at the same time viewing the list of supported formats. If the type to be opened is not there, produce someor you don't even have to try to act with the object.
Using archiving programs
If UltraISO gives a message about an unknown image format even for registered and fully supported file types, try opening the search object in any archiver available on your computer.

WinRAR and 7-Zip programs are best suited for such purposes. In addition to the main tools, they have the ability to use file-by-file extraction of components, which allows you to save important files on your hard drive for further repacking into an image.
Opening IMA and WIC images
Another common situation with the appearance of a message about an unknown image format in UltraISO may be related to the cloning of data originally stored on removable media, when at the output, without user intervention, an IMA file that seems to be associated with the program is created, but subsequently it is not opened by the main application or similar programs.

In this case, oddly enough, the almost forgotten Win32 Disk Imager utility helps. But with its help, you can extract data from the image, so that later you can create a new image or the same bootable flash drive from them.
As for the UltraISO package itself, just in case, it is recommended to download and install its latest version. Sometimes you can still try to open the image in another similar programor even restore the archive via WinRAR. It is possible that this approach will get rid of the problem.