Is there none that can supply some "trade" information regarding the methods, file formats etc - of modern books / manuscripts? I expect, if the graphics was ever available as such - or designed so by the publisher - they would be stored as vector graphics, unrendered or uncompressed original formats. Complex images though, aren't impossible to do by vector - but extremely time consuming.
As have nicely been informed by the other users here - with older, "analog" media (video and audio), the primary function of the "Master" was to branch out a handful of copies, and duplicate further from those - due to physical wear and tear during the copy process. Books were "set" manually, and the letters separated after the print was run. Original manuscripts were usually print or writing on paper, depending on age.
In modern day - the "Master" still serves as an unadulterated original (and this is usually duplicated several times) - but not primarily due to wear and tear during a copy process. A straight 1:1 digital copy does not pose any wear on the original, or detoriation of the new copy. Its all 1s and 0s. Most data transfer processes have data corruption control. The "recieving" end will let the "sender" know what it actually got. If the data don't match the original, the "sender" will send that package again. This will loop util it "gets it right" or a defined limited set of times (whatever occurs first) - this "limit" can be indefinite.
Don't confuse this with the actual manufacturing of "digital media" like CDs, DVDs and Blu-Ray discs. The actual transfer process from the "manufacturing master", is physical pressing. Any physical pressing procedure, is actually very much analog - and thus both long-time wear or a foreign object like a speck of dust, can introduce detoriation (resulting in data corruption).
There are 2 other important aspects of "Digital Master Copies" to keep in mind.
First off - most of todays digital storage media, will be detoriate with time. This is mostly down to physical properties of the materials the storage media is manufactured from. Paper and cellulose film will deteriorate too. 111
So will modern polyester film eventually, but its designed to last for hundreds of years given ideal circumstances. But the good thing about digital media, is that its fairly easy and little work - to replicate and migrate to a new "Master Copy". It is also fairly easy to make it automated, if you administer hundreds or thousands of "Masters".
Second: A digital master copy is usually completely without compression. Which means, its VERY, VERY, VERY large. If the format is 24 frames per second - then thats what this copy will be: 24 full uncompressed images per second of "film". A "standard" Blu-Ray disc (double layer) may hold up to 50 Gigabyte of data. Special triple layer discs may hold as much as 128 Gigabytes, although these are rare.
Now consider a modern, HQ shot 3D movie like The Hobbit: The Desolation of Smaug . This was shot in 48fps, 3D 5K resolution. Now lets do the math for the uncompressed, RAW digital video data (without sound). (Some numbers are theoretical likeliness, as I couldn't find those filming details) :
24 (bit color depth) * 5120 (pixels horiz.) * 2700 (pixels vert.) * 48 (frames per second) * 2 (for 3D, stereo (2 images "per frame")). Without ANY compression, that is <PHONE_NUMBER> bits per second of film - or 3,7 Gigabytes. Per second of film. Thats almost 50 Terrabytes for a 3 and a half hour movie.
Now, even a FullHD (1080p), 24 fps movie at this bit depth would be ~142 Megabytes per second, ~1.8 Terrabyte for 3.5 hours. It goes without saying - you can't store that Digital Master spread over a thousand (or 35 in the "1880p/24fps case") Blu-Ray discs - some other storage media must be used. And to squeeze this raw digital movie footage onto a Blu-Ray disc, is actually going to require some very serious compression. 896