Re: [tlug] JPG & GIF Issue

[Matt Gushee <mgushee@example.com>]

Lyle (Hiroshi) Saxon wrote:
> bruno raoult wrote:

> I meant copying from the floppy to the hard drive.

Using the 'cp' command in the shell, or a graphical file manager? I've 
never heard of a file manager that won't copy files that it thinks are 
broken, but developers are doing all kinds of weird things these days in 
their efforts to make Linux more user-friendly. Anyway, 'cp' should work 
on anything that is identifiable as a file. So if you did use a 
graphical tool, I'd suggest trying 'cp' just to be sure.

> The strange thing 
> was that the half-downloaded file could be opened - but only half the 
> picture was there.

That's normal. What else would you expect?

> floppy.  Can different compression rates affect the ability to copy 
> files?

I can't give you a definite answer, but it seems extremely unlikely.

> It doesn't seem like they could, but that was the only thing 
> different about the file from the others (and it wasn't just a broken 
> file

Do you mean it wasn't *just* a broken file, or it wasn't a broken file 
at all? Don't know? Two utilities that will tell you:

   identify  (part of the ImageMagick suite--you probably have it
              already)
   jpeginfo

Personally, I prefer jpeginfo: it gives you all the info you're likely 
to need and is faster than identify. But it only works on JPEGs, and you 
probably have to install it. Identify (in verbose mode) tells you 
*everything* about an image, most of which you don't need to know. It 
works on many kinds of images, though.

>> More likely, the floppy could not be read for some reason.
> 
> Right.  But that "some reason" seems to have something to do with the 
> .jpg compression rate.....(?).....

Or the floppy has some bad sectors, and the odd JPEG was coincidentally 
saved to that part of the floppy. A fluke, yes, but not at all a 
far-fetched one. It seems much more likely than the compression ratio 
preventing copying.

In summary, I'd suggest:

  1) Attempting to copy the file with 'cp'.

  2) Testing it with one of the above-mentioned utilities.

  3) Trying a different floppy and/or some other means of moving the
     file.

By the way, why not use PNG? Even though the GIF patent problem is 
supposed to be over, GIF can make photos look crappy--gives them 
unnaturally sharp edges, for example. Whereas every PNG photo I've ever 
seen looked just as good as a JPEG. JPEG files are much smaller, of 
course, which is probably why they're still recommended for photos. But 
if for some reason JPEG isn't doing what you need ...

Some browsers still have problems with transparency in PNGs, but of 
course that's not relevant here. Is *anybody* still using browsers that 
just won't display PNGs? Maybe a couple dozen old curmudgeons up in the 
Pennsylvania hills (or the Japanese equivalent, wherever that is). 
Nothing to lose sleep over.

--
Matt Gushee
Englewood, CO, USA