Dynamic Web TWAIN holds the images in buffer in memory as Bitmap format.
From version 9 of Dynamic Web TWAIN, two new APIs called IfAllowLocalCache and BufferMemoryLimit are available to store images in encrypted local cache file. The default value of BufferMemoryLimit is 800 - which means Dynamic Web TWAIN uses 800MB of memory space to store images. When the total size of images exceed the limit, images will then be cached to local encrypted files.
The new feature makes it possible to scan thousands of pages at a time without running out computer memory.