Is it true that the theoretical maximum size PDF file is larger than Germany?
One of the internet memes scattered on the Internet is that ``A PDF file with maximum page size is larger than the land area of Germany.'' Software developer Alex Ulchan explained whether this is really true.
Making a PDF that's larger than Germany – alexwlchan
The meme in question is below. The theoretical maximum size PDF file would be 381 kilometers square, which is claimed to be larger than Germany. However, there is no support or explanation for this claim, and we do not know why the upper limit is 381 kilometers.
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Some people have pointed out that this is due to the upper limits of PDF file readers, and have pointed out the specifications of Adobe Acrobat, saying, ``Adobe Acrobat has a maximum size of 15 million inches x 15 million inches, or 225 trillion square inches (225 trillion square inches). This figure is due to the restriction of 381 kilometers x 381 kilometers or 145,161 square kilometers). In fact, the same thing is said in the PDF 1.6 specifications .
I found out that the largest PDF file size seems to be larger than Germany, but Mr. Ulchan decided to try it out to see if ``381 km square'' is really the largest.
Mr. Urchan first learned the internal structure of PDF files and understood how to edit PDF directly, and understood that the 'Page' object determines the size of the page.
For example, if '/MediaBox [0 0 300 300]' is specified in the Page object, the dimensions will be a 300 x 300 square. The default unit size is 1/72, so one page is 300 x 72 = 4.17 inches (10.59 cm). You can make the page even larger by changing the value of this 'MediaBox'.
However, when I increased the MediaBox value to 14,400 x 14,400, the maximum allowed by Adobe Acrobat, it displayed that the page was now 200.00 x 200.00 inches, and that a warning would appear if I tried to exceed this limit. thing. 200 inches is only 5 meters, which is far from 381 kilometers.
According to Mr. Urchan, this is because the default unit of 1/72 inch is used, and by changing the value of UserUnit, it is possible to increase the unit and break through the limit. However, when Mr. Urchan raised the UserUnit to the maximum value of 75,000, Adobe Acrobat displayed that the page size was 15 billion inches x 15 billion inches (381 kilometers x 381 kilometers), and even if the size is larger than this, Even if it was created, the display of '15 billion inches' no longer changed.
Therefore, Mr. Urchan used the macOS application 'Preview.app', which has no upper limit on MediaBox. When I increased the dimensions dramatically, it seems that I was able to create a file with a page size of 35,277,777,777.78 cm x 10.59 cm. This width is approximately the same as the distance between the Earth and the Moon.
This number can still be increased, and it seems that they were able to create a PDF of approximately 37 trillion light years square (1 light year is approximately 9.5 trillion kilometers). This file (PDF file) can be accessed from this link , but Mr. Urchan cautioned, ``Please do not print it.''
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• Discord | 'Have you ever encountered a PDF file that was too large? What type of document and how much space did it have?' | GIGAZINE
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