Sending pictures - technical
Daniel Kropveld (KROPVELD@AMC.UVA.NL)
Wed, 10 Apr 1991 16:31:00 MET
there have been some questions on this list on how to send pictures.
Maybe I can help.
Sending pictures is not easy, but it can be done if you are aware of the
1) Pictures are in binary format. (8 bit bytes)
Networks and software connected to networks often don't like binary.
You will find that when you send binary files they often get misformed:
8th bit stripped off, unwanted record seperators added, or even complete
bytes mangled (because of ASCII-EBCDIC (vv) translations).
A solution is to convert the picture-file to a 7 bit code, send it over
the network, and at the receiver convert the 7 bit code back to binary.
The tools to do this job is UUENCODE and UUDECODE:
UUENCODE converts the file to a format that the network likes to
handle. You can send the file just like it were a piece of plain text, by
eMAIL. (Actually it *is* plain text). The receiver can extract the
message to a file, strip the header off (that may not even be needed)
and decode the file back to binary. The penalty you pay is that the file
increases its size of about 20% - 30%.
UUDECODE is the tool to reconvert the file to binary.
There are UU*CODE programs available for just any type of computer.
2) Picture-files are mostly big.
And mostly needlessly big, when there are large areas of the same shade.
There are many tools to compress pictures. These programs are called
Archivers. Archivers not only compress (picture-)files, but also can
also store a whole set of pictures into one archive-file.
PkZip was mentioned on this list. There are others too.
ARC - very popular on PC's, and widely available on other computer
ZOO - compresses better, and is more tolerant on exotic filenames.
LHARC - IMHO the best, but I have seen it only on UNIX systems and AMIGA
ZIP, ZAP... and lots of others. These may be very fancy and advanced
stuff, and it may be fine if you have this software, but one may run
into trouble if the receiver has an other computer than the one you have.
3) Picture files have different formats.
Pixel-size (ie 320x200) or number of colors (ie 16) is generally not a
problem because changing sizes is easy, but the way a picture is stored
in a file *is*.
Every drawing program has its own way of storing the picture, which is
mostly incompatible with the other drawing program. There are hundreds
of picture file formats now, and new ones coming out regulary.
Two popular standarized picture formats are GIF and TIFF. The TIFF
format, (I think) is the better one, but GIF is far more used.
(GIF stands for Graphics Interchange Format)
And the converters to and from ( my-file-format2GIF and
GIF2my-file-format) are available for every system, and for almost
every picture-file format. Look around on your local BBS.
So here is my suggestion if you want to distribute a picture over the
1) Convert your picture into GIF format.
2) Archive your picture into an ARC archive.
3) Run your ARC file through UUENCODE
4) Send the UUencoded file off. Mention in the subject line that this is
a UUencoded picture file.
1) Extracts the Mail into a file.
2) Runs UUDECODE on it.
3) Extracts the files from the ARC-archive.
4) Converts the GIF-format into the format of his/hers favorite viewer.
5) Displays the picture.
Note that the resulted UUencoded files should not be too big.
The network, nor the receiver with limited quota may not like big Mails.
Send only one picture per Mail. The network is better with handling several
Personally I picked up the Order of the Arrow archive from the
LISTSERVer, and it took me quite a lot of effort to convert the
MacIntosh-format picture files to my own Amiga's IFF-file format.
But I succeeded - the only problem I have now is that I do not know what
all these symbols mean (I am not a member of the BSA). Maybe someone can
In return I can send these IFF-files to any AMIGA user, who requests them
in a personal Mail to me. They will be in a ZOO archive (Amiga's standard)
I like to receive pictures (see procedure above) about scouting.
Although I am not involved in Dutch Scouting either, I do like
to return digitized pictures (about Dutch Scouting), if requested.
Yours in ... Youth-Work
Daniel Kropveld, Amsterdam.
Excuses for my English, I wrote this in a hurry.
Terry Howerton Sakima Group, Inc. SCOUTER Magazine Kansas City