Re: [S] binary _to_jpg

Prof Brian Ripley (ripley@stats.ox.ac.uk)
Thu, 23 Jul 1998 16:04:47 +0100 (BST)


> From: srosenfeld@nesdis.noaa.gov
> Date: Thu, 23 Jul 98 10:29:23 -0500
> Subject: [S] binary _to_jpg
> To: s-news@wubios.wustl.edu
>
> Dear S'ersPLUS!:
>
> Many thanks to Thomas Schmugge, Prof. Brian Ripley and especially to Bob
Henery
> for fast response. Now I inderstand that the obstacle for transition from
binary
> to JPG is that S_plus does not handle one-bite data (so far, of course!)

byte, I hope. Svr4 and therefore S-PLUS 5 has a raw data type, but
I still would not use S-PLUS.

>
> Therefore, I want to slightly simplify the task. I transform binary matrix
into
> the 3-digits integer matrix outside S-plus (using, say, a FORTRAN module
> launched from S-PLUS). How to proceed from this point?
> What I need is an entirely automatic procedure without any keyboard
> interventions (INPUT: a million of binary files, OUTPUT: a million of
JPG(BMP?)
> files)
>
> I work with S+3.3/4.5 on Pentium2/400MGz/128RAM under W95/98

As I said before privately I think the solution is just to launch an
external convertor. Why re-invent the wheel? ImageMagick's convert
program will convert

GRAY Raw gray bytes.
to
GIF CompuServe graphics interchange format; 8-bit color.
GIF87 CompuServe graphics interchange format; 8-bit color (version 87a).
JPEG Joint Photographic Experts Group JFIF format; compressed 24-bit color.

and many others. And it is available for Windows NT (runs on 95).
http://www.wizards.dupont.com/cristy. (You don't need Xwindows to run convert,
so do not be put off by the docs.)

If it really is a million, I would not go near S-PLUS unless you are
very very confident of no memory build up. And at 2 sec/image it will
take a month. And even small examples (32 x 32, rather small for JPEG)
take a gigabyte of input. And does your Windows 9x machine stay up that long?

-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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