ISM files are associated with Image System and they most likely contain a bitmap image that was created a long time ago. A similar image format associated with Image System is ISH, which contains high-resolution images, while ISM contains multicolor images. Opening both formats might pose difficulties when using a regular image viewer, so converting them to more accessible formats is probably the best solution for easier opening and transferring.
The quick and simple way to handle your files is to get a quality piece of software, such as reaConverter. This software is extremely efficient in managing a wide range of batch conversions. As you will soon realize, reaConverter will help you avoid spending countless hours trying to figure out how to convert multiple ISM files as once.
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