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Re: xv

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On Sun, May 23, 2021 at 4:33 AM Thomas Schmitt <scdbackup@gmx.net> wrote:

> Hi,
>
> Dan Hitt wrote:
> > Thomas, that sounds awesome, please do post somewhere (and provide a link
> > here, if you would be so kind).
>
> So on popular demand by one potential user here it is
>
>   http://scdbackup.sourceforge.net/halve_jpeg.c
>
> SHA256SUM:
>   b4c9322cd7d20a09a5196ccbcec257bf363d9dea1284333afc9624ff6a05dcc0
>
> It needs installed libjpeg development header files and runtime library.
> To my theory that would be package "libjpeg62-turbo-dev" which brings
> the runtime as dependency.
> The tools for compilation get installed by meta-package "build-essential".
>
> Compile the program by
>
>   cc -g -Wall -o halve_jpeg halve_jpeg.c -ljpeg
>
> Test by converting some file
>
>   ./halve_jpeg -geometry 1280x1024 large_input_pic.jpg
> ermerging_small_pic.jpg
>
>   xv ermerging_small_pic.jpg
>
> The -geometry argument defines a frame into which ermerging_small_pic.jpg
> will fit while retaining its x:y ratio.
>
> For permanent use, copy the file ./halve_jpeg to a directory where the
> shell
> will find it.
>
> It is not very good with enlarging images. My motivation was to condense
> JPEGS with zillions of pixels to screen size without blasting my RAM which
> was only 2 GB at that time.
>
>
> Have a nice day :)
>
> Thomas
>
>
Thanks Thomas for posting it.

On xubuntu 20.2 i was able to compile it after installing some jpeg
packages:
sudo apt-get install jpeginfo libjpeg-dev libjpeg-progs libjpeg-tools

I think some of these names may be generic and point to the turbo code, i'm
not sure.  I tried just installing all jpeg packages but got conflicts, so
i pared down the list until i could install.

The code compiled quickly.

It was unwilling to deal with a non-color image that i had ("Unsuitable
JPEG format with 1 components per pixel"), but on color images it works and
is very fast.  And since you were so nice to provide the source code, if i
need to deal with non-color images, i can try to modify it.

Thanks again!

dan

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Re: xv Dan Hitt <dan.hitt@gmail.com> - 2021-05-23 03:30 +0200
  Re: xv Dan Hitt <dan.hitt@gmail.com> - 2021-05-23 19:30 +0200
    Re: xv "Thomas Schmitt" <scdbackup@gmx.net> - 2021-05-23 22:30 +0200
      Re: xv Dan Hitt <dan.hitt@gmail.com> - 2021-05-24 00:40 +0200
  Re: xv "Thomas Schmitt" <scdbackup@gmx.net> - 2021-05-23 13:40 +0200

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