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From: Jolly Roger <jollyroger@pobox.com>
Newsgroups: comp.sys.mac.system
Subject: Re: Any quick, easy way to compare two images?
Date: 27 Jan 2014 19:14:23 GMT
Organization: People for the Ethical Treatment of Pirates
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Message-ID: <bknpgfF22s8U1@mid.individual.net>
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On 2014-01-27, nospam <nospam@nospam.invalid> wrote:
> In article <bklkd7Fib1cU2@mid.individual.net>, Jolly Roger
><jollyroger@pobox.com> wrote:
>
>> > As explained elsewhere (in multiple ways, on multiple occasions, but 
>> > still somehow eluding DAMN NEAR EVERYBODY despite my efforts to be so 
>> > clear that no misunderstanding could be possible) my program is 
>> > snatching images from a webcam (AKA "pushing the button on the magic 
>> > box" of the analogy, AKA the original "assemble a stream of webcam 
>> > images" in my first post) that *NOMINALLY* updates the image on a 
>> > website every 60 seconds.
>> 
>> So rather than pulling images directly from a network camera, you are,
>> in fact, pulling images from a web site indiscriminately? That's quite a
>> different use case, as I see it. In that case, examining the
>> "Last-Modified" HTTP header will tell you if the image is in fact new,
>> which would allow you to refrain from pulling the same image more than
>> once.
>
> how hypocritical of you.
>
> apparently you don't understand that header may not always be correct
> and it's likely the file's modification date anyway. 

Maybe you don't have enough experience with network cameras to see
what's going on here. A common feature of network cameras is to
automatically upload snapshots to an ftp/web server. The OP has stated
that, for this particular camera, that upload happens at random
intervals. The OPs software downloads the image from the web server at
different intervals than the camera uploads them. Therefore when the OPs
software downloads an image from the web server, the image on the server
at the time may be the exact same image the OPs software got the last
time it downloaded an image from the server. Examining the last-modified
header / file modification date in this case will be sufficient to
refrain from downloading the same image.  If you can't wrap your little
brain around that, contact your local therapist for assistance.

You've proven yourself to be a complete jackass. Good work, Mary.

-- 
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I often ignore posts from Google. Use a real news client instead.

JR