Linearizing PDF scans

Peter Corlett abuse at
Sun Aug 15 13:36:48 CDT 2021

On Sun, Aug 15, 2021 at 01:29:37AM -0400, J. David Bryan via cctalk wrote:
> On Sunday, August 15, 2021 at 12:55, Kevin Parker wrote:
>> ...but on my limited understanding it required support from the web
>> server to actually give effect to this.
> I believe that's right. At least all of the servers I used seemed to
> support this option.

The option in question is called "range requests" and is documented in the
original HTTP/1.1 standard from way back in 1997. Any web server worth its
salt should support it automatically when serving static files. It's used
for resuming downloads, for example.

> Assuming one only looks at a few pages, it would certainly reduce the
> amount of data served, though, of course, if one requested the entire
> file, it would actually be a slight disadvantage.

A larger disadvantage is the pause to download the next page when leafing
through a PDF, which can be quite distracting to people who can read without
moving their lips.

> As you say, it requires server support, and to be honest I've not checked
> recently to see if servers bother byte-serving anymore. [...]

If a server lacks support for range requests, it is either very old or a
small hobby project, and shouldn't be let anywhere near the public Internet.

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