[8] Macintosh

Most Mac JPEG programs rely on Apple's JPEG implementation, which is part of
the QuickTime system extension; so you need to have QuickTime installed.
To use QuickTime, you need a 68020 or better CPU and you need to be running
System 6.0.7 or later.  (If you're running System 6, you must also install
the 32-bit QuickDraw extension; in System 7, that is built in.)  The latest
version of QuickTime is 2.5, available from http://quicktime.apple.com/.

Mac users should keep in mind that QuickTime's JPEG format, PICT/JPEG, is
not the same as the Usenet-standard JFIF JPEG format.  (See part 1 for
details.)  If you post images on Usenet, make sure they are in JFIF format.
Most of the programs mentioned here can handle either format.

Another thing to be aware of is that QuickTime still does not handle
progressive JPEG, so Mac programs won't either unless they include their
own JPEG code.  Most of the programs suggested here do.

The two major Internet sites for Mac software are sumex-aim.stanford.edu and
mac.archive.umich.edu.  Unfortunately they are both very busy, so you may
have better luck getting files from a mirror site.  (In fact, these days
you *must* use a mirror site for sumex-aim; the primary archive only allows
mirror sites to log in!  The sumex-aim FTP pointers given below are
therefore useless as-is; you *must* substitute a mirror site name.)  See
"Introductory Macintosh Frequently Asked Questions" in the comp.sys.mac.*
newsgroups for the current locations of mirrors.

JPEGView is an excellent free program for viewing JFIF,PICT/JPEG,GIF,TIFF,
and other image files.  It can convert between the two JPEG formats and can
create preview images for files.  The current version is 3.3.1, available
from sumex-aim.stanford.edu:/info-mac/gst/grf/jpeg-view-331.hqx.  Requires
System 7; QuickTime is optional.  JPEGView is a fine viewer with an unusual
but well-thought-out design (no scroll bars, for example).  Unfortunately,
it hasn't been updated in a long time, and is starting to show its age.
There are reports of bugs under System 7.5.3, and it doesn't handle
progressive JPEG.

Jade is a new, very promising freeware viewer for JPEG, GIF, PICT, and
BMP images.  It's fast, simple to use, and has preview and slideshow
capabilities.  And it supports progressive JPEGs.  Since JPEGView is no
longer being updated, Jade will probably supersede it as the most popular
free Mac JPEG viewer before long.  Current version is 1.2, available from
sumex-aim.stanford.edu:/info-mac/gst/grf/jade-12.hqx.  Requires 68020
(or higher) or PowerPC, as well as System 7.5 (or later) or Thread Manager.

GIFConverter, a shareware ($40) image viewer/editor/converter, supports
JFIF,PICT/JPEG,GIF, and many other image formats.  Current release is 2.3.7,
mac.archive.umich.edu:/mac/graphics/graphicsutil/gifconverter2.37.cpt.hqx.
Newer beta versions are available at http://www.kamit.com/gifconverter.html.
Requires System 6.0.5 or later.  GIFConverter is not better than JPEGView as
a plain JPEG/GIF viewer, but it has much more extensive image manipulation
and format conversion capabilities.  Also, GIFConverter is your best bet
if your machine is too old to run System 7 and/or QuickTime.  Hint: if
GIFConverter runs out of memory while loading a large JPEG, try converting
the file to GIF with JPEG Convert, then viewing the GIF version.

GraphicConverter is another popular viewer/editor/converter.  It has even
more functionality than GIFConverter, but is correspondingly larger.  Great
if you like lots of options.  Shareware, $35.  Current version is 2.5,
sumex-aim.stanford.edu:/info-mac/gst/grf/graphic-converter-25.hqx.

Sam Bushell has prepared a couple of simple but nicely done drag-and-drop
converter applications, "To JPEG" and "Progressify".  To JPEG converts any
file format understood by QuickTime to regular or progressive JPEG;
Progressify converts losslessly between regular and progressive JPEG
formats.  Both are free and require System 7.0 or later.  Available from
sumex-aim.stanford.edu:/info-mac/gst/grf/to-jpeg-10.hqx and
sumex-aim.stanford.edu:/info-mac/gst/grf/progressify-10.hqx.

If you are still running a pre-7.0 system, another freeware alternative is
JPEG Convert, a Mac version of the IJG JPEG conversion utilities.  It's too
old to know about progressive JPEG, so I don't recommend it unless you can't
run any of the above choices.  Runs on any Mac, available from
sumex-aim.stanford.edu:/info-mac/gst/grf/jpeg-convert-10.hqx.

Photoshop 4.0 supports progressive JPEG.  If you have an older version,
you can get two different plugins that enable progressive JPEG support
(they also work in other applications that support Photoshop plugins).
One is ProJPEG, available from ftp.boxtopsoft.com:/pub/ProJPEGv2.1.sit.hqx
(shareware, $25).  The other is JPEG Transmogrifier's plugin version,
available from ftp.best.com:/pub/gyld/plugin.sea.hqx (shareware, $22).
ProJPEG is worthwhile even with PS 4.0, because it has a nifty preview
of the results of different compression settings.

HINT: You must set the file type code of a downloaded JPEG file to 'JPEG'
to allow Photoshop to recognize it.  Most of the other programs suggested
here are not so picky about file type codes.

HINT: if you use Fetch to retrieve files by FTP, make sure ".jpg" is in its
list of binary file types under Customize/Suffix Mapping.  Otherwise Fetch's
"automatic" retrieval mode will retrieve JPEGs in text mode, thus corrupting
the data.  Old versions of Fetch do not include ".jpg" in the default list.
Also, Fetch 3.0 is buggy; get 3.0.1.