Datatid 2000 #1/Datatid-2000-01.iso/nyt/projpeg/PROJPEG FAQ.TXT

Text File | 1998-10-21 | 13.6 KB | 324 lines

ProJPEG FAQ - revision #2 - 10/21/98

BoxTop Software, Inc.
PO Box 2347
Starkville, MS, 39760
voice 601-263-5410
fax [phone]
http://www.boxtopsoft.com
ftp://ftp.boxtopsoft.com/pub
[e-mail]


Contents:

1: Why should I buy ProJPEG and not ImageReady or FireWorks?

2: Will ProJPEG work with PhotoPaint, Painter, Canvas, ColorIt!, etc.?

3: I installed ProJPEG, but I don't see it in my filters menu. What's up?

4: I installed ProJPEG for Windows and I'm looking for it in the right
place, but I still don't see it?

5: I was using ProJPEG and it said "The operation could not be completed
because there was not enough memory." What's wrong?

6: I opened a JPEG file saved with paths using ProJPEG and the paths
were gone, is this a bug?

7: Are ProJPEG files compatible with PageMill, etc.?

8: Can I batch process with ProJPEG?

9: When I go to save my document with ProJPEG, the option isn't
available in Photoshop's format's menu. It's grayed out. Why?

10: The size of the final file in ProJPEG's dialog isn't the same size
as I see in the Finder. Which one is right and why are they different?

11: I saved my file with ProJPEG and when I opened it back up in
Photoshop, it was the exact same size as before? I thought it was
supposed to make it be smaller. What am I missing?



1- Q: Why should I buy ProJPEG and not ImageReady or FireWorks?

A: To get smaller files faster with less effort and save yourself some
money doing it. There really is no better reason to chose ProJPEG than
the fact that ProJPEG is the best tool at the best price.

ImageReady and FireWorks are both good applications, but face it,
neither one compares to Photoshop for image editing and neither compares
to ProJPEG for making Web JPEG files. It doesn't make very much sense to
get another stand alone application just to save your JPEG files for the
Web when it can be done better and faster from Photoshop with ProJPEG.

- ProJPEG makes drastically smaller files
- ProJPEG is much easier to use
- ProJPEG is much faster to use
- ProJPEG is about 1/6th the price
- ProJPEG doesn't use 20 MB more RAM
- ProJPEG doesn't use 30 MB of your HD

There are many greatly compelling reasons to chose a plug-in solution
for your Web graphics needs despite the combined marketing budgets of
Adobe and Macromedia.



2 - Q: Will ProJPEG work with PhotoPaint, Painter, Canvas, ColorIt!,
etc.?

A: No. ProJPEG is a file format plug-in and as far as we know, no
non-Adobe applications support this type of plug-in. Only Adobe supports
file format plug-ins.

ProJPEG is just for Photoshop, but it should actually work with Adobe's
other image editing products, which generally also support file format
plug-ins.



3 - Q: I installed ProJPEG, but I don't see it in my filters menu.
What's up?

A: ProJPEG isn't a filter plug-in. It doesn't appear in your filters
menu. ProJPEG is a file format plug-in. File format plug-ins add new
opening and saving capabilities for files to Photoshop and appear as
menu items in the formats menu in Photoshop's dialogs for opening and
saving files - not in the filters menu.

You can tell if ProJPEG is installed correctly and being recognized by
Photoshop by looking in the "About Plug-ins" menu in Photoshop. If
ProJPEG is installed correctly and recognized you will see a menu item
named "BoxTop ProJPEG" in that menu.

When ProJPEG is installed you use it by saving files as "BoxTop ProJPEG"
(Mac version) or "ProJPEG" (Windows version) in Photoshop's save dialog
instead of just "JPEG", which is the name of Photoshop's own JPEG format
module.



4 - Q: I installed ProJPEG for Windows and I'm looking for it in the
right place, but I still don't see it?

A: The installer Wizard for the Windows version of ProJPEG 3.0 needs to
be told where your plug-ins directory is using the "Browse" button.
Apparently, this step is easy to miss. If you've installed ProJPEG
without designating where your plug-ins directory is, you should use the
included uninstal application to remove ProJPEG and then re-install
taking care to specify the location of your plug-ins directory.

If you don't use the un-installer first sometimes it doesn't want to
work right installing the second time.

With ProJPEG 3.1 for Windows, there is no installer Wizard, because the
Wizards seemed to cause more problems than they solved. It is in a zip
archive and installation is as simple as copying the plug-in to
\Photoshop\Plugins\Formats



5 - Q: I was using ProJPEG and it said "The operation could not be
completed because there was not enough memory." What's wrong?

A: There's not enough memory available to ProJEPG to complete the
operation - exactly what the error message says.

Memory availability with Photoshop plug-ins is a tricky business because
they can only use what Photoshop isn't already. Under ideal conditions,
which never really happen, ProJPEG is able to use at most 1/3 of the RAM
allocated to Photoshop. That means if you have 25MB of memory allocated
to Photoshop, then ProJPEG can use at most about 8MB, and more likely it
can only use about 6MB with Photoshop set to a 25MB application
partition.

6 - 8MB is plenty of RAM to save 90% of the images you would ever want
to put on a web page, but it's not enough for a large or hi-res image.
ProJPEG has a very high memory overhead from the interactive previews.
It needs twice the size of the original RGB image just for those two
previews, and then about a MB of fixed overhead to be able to save a
baseline JPEG. Saving the image as progressive further increases the
memory overhead considerably.

The reason ProJPEG can take such liberties with memory requirements is
because the average size of images for the web is well under a MB of
uncompressed RGB data. For instance, a large 640 x 480 pixel image is
only 900K of uncompressed RGB data.

However, an apparently smaller (in dimensions) hi-res image that's 4 x 5
inches at 220ppi is 3 times larger at 2.8MB in size, and could cause a
memory error in ProJPEG easily if you haven't increased Photoshop's
default memory partition of 16MB. The same is true of any large image,
because it takes more memory than you think to save an image with
ProJPEG and less memory than you think is available for ProJPEG to use.

To improve ProJPEG's and Photoshop's performance, you should increase
Photoshop's RAM to as much as you can. (Photoshop can never have too
much RAM.) You can also clear undo information, clear the clipboard,
clear snapshots, and close extra documents to improve memory conditions
for ProJPEG and other plug-ins.

If all else fails and you simply don't have enough physical RAM
available for that huge image you just have to have - against all
practical advice - on your web page, you can always save with
Photoshop's built in JPEG. Photoshop's JPEG is quite different from
ProJPEG in that it's not implemented as a plug-in and not subject to the
same memory related limitations, which is presumably why Adobe chose to
abandon their own plug-in interface for most of their file format
support. Photoshop's JPEG is optimized for hi-res print images, and will
not achieve the same level of compression as ProJPEG, but it is able to
save tremendous files because it doesn't have the memory constraints of
plug-ins and it doesn't have an interactive interface that requires a
high memory overhead.



6 - Q: I opened a JPEG file saved with paths using ProJPEG and the paths
were gone, is this a bug?

A: Nope. It's not a bug. Paths are proprietary to Photoshop, and ProJPEG
simply doesn't support them. It won't save them. It won't read them.
However, it will read JPEG files that have paths, and other kinds of
application specific, proprietary information in them, it will just
ignore it reading only the image information.

Should you need to open a JPEG file with paths, you should use the Open
menu in Photoshop and select "JPEG" as the format to read the file.



7 - Q: Are ProJPEG files compatible with PageMill, etc.?

A: Yes. ProJPEG saves ordinary JPEG files that comply fully with the
JFIF specification. (JFIF is the actual file format. JPEG is a popular
misnomer.)

By default ProJPEG saves non-progressive JFIF JPEG files, which are
compatible with nearly every application that has any sort of "JPEG"
support. However, ProJPEG can save progressive JPEG files, which are a
less supported variation of the JFIF format that some applications do
not support, like PageMill and several other current versions of popular
WYSIWYG editors.

This isn't a problem with ProJPEG's files, and not really an issue to
worry about at all. All of the current browsers support progressive JPEG
files now, but if you want JPEGs that anyone and any application can
open, just don't turn the progressive option on in ProJPEG.

There is some advantage to using progressive JPEG files because they
appear to load faster to the viewer because of incremental display
similar to interlaced GIFs and usually are smaller, but this has to be
weighted against some compatibility concerns. ProJPEG leaves that choice
up to you, but progressive isn't the default anymore because too many
people asked why files wouldn't display in PageMill.



8 - Q: Can I batch process with ProJPEG?

A: Yes. ProJPEG (Version 3.1) fully supports actions and can be scripted
for batch processing of images in Photoshop 4 and 5.



9 - Q: When I go to save my document with ProJPEG, the option isn't
available in Photoshop's format's menu. It's grayed out or missing all
together. Why?

A: Photoshop disables format options when there is information in the
working document file that the individual format module isn't able to
save. In ProJPEG's case it is because:

- Your document isn't in RGB or Grayscale mode. ProJPEG can only save
documents that are in RGB or Grayscale mode.

- Your document contains layers. The file format plug-in API doesn't
have access to layers in Photoshop and no file format plug-in can save
documents using layers because of it.

- Your document has alpha channels. ProJPEG doesn't support saving alpha
channels.

When ProJPEG (or another format) is disabled in the format menu in the
"Save as..." dialog, you can use "Save a Copy..." instead with "Flatten
Image" and "Don't Include Alpha Channels" checked to save with a
previously disabled format, except when it was disable because of the
document's color mode.



10 - Q: The size of the final file in ProJPEG's dialog isn't the same
size as I see in the Finder. Which one is right and why are they
different?

A: First, the final size shown in ProJPEG's dialog is the right one.
That is exactly how big your JPEG file will be after you hit the OK
button and ProJPEG writes the file to disk. It's already compressed it
in RAM to know the exact final size, so it is accurate to the last byte.

That's only the JPEG file, though. It doesn't count any application and
Mac specific resource information that Photoshop will save in the
resource fork of your Macintosh "file" such as custom icons, previews,
printer settings, etc.

For technical reference, the Macintosh file system uses two files, one
called the data fork and one called the resource fork for every "file"
you see on the desktop. Your JPEG file is the data fork of that Mac
file, and whatever is in the resource fork of that Mac file is extra
fluff that doesn't count as far as the Web or JPEGs are concerned. When
you upload the file to your server the resource fork is never sent and
even if your Web server happens to be a Mac, the resource fork is never
sent in response to a request. It's just extra Mac info that other
computers don't understand.

The difference comes in because the Finder shows the combined size of
the data fork and the resource fork in the Get Info window, and there is
no way from the Finder to just see the size of the data fork, which is
what you want to know for GIF and JPEG file purposes.

You don't really need to worry about what the Finder says, as long as
you're happy with the file sizes in ProJPEG. The extra information in
the resource fork will take up a little extra room locally on your hard
disk, but it won't effect your Web page at all. The custom icons and
previews are worth keeping because they make sorting through images much
easier.

However, if you want the size you see in ProJPEG to agree with the size
you see in the Finder, you can download GIF Prep from the BoxTop
Software, Inc. Web site and use it to strip the resource forks from your
GIF and JPEG files. GIF Prep is free. We pretty much wrote it to help
answer this question that is asked too often.



11 - Q: I saved my file with ProJPEG and when I opened it back up in
Photoshop, it was the exact same size as before? I thought it was
supposed to make it be smaller. What am I missing?

You're missing the difference between a compressed file on disk and an
open image document of uncompressed pixel data. That's a big difference.
An RGB image of the same dimensions is always going to be the same size
based on a simple formula of 3 bytes per pixel of data. That isn't the
same thing as a JPEG file, but that is what Photoshop reports the size
of - the open document, which is in that state just a bunch of
uncompressed pixel data abstracted from any file format.




ProJPEG is Copyright 1995-98 BoxTop Software Inc. All rights reserved.
ProJPEGis a Trade Mark of BoxTop Software Inc., which may be registered
in certain jurisdictions. All other trademarks are recognized as the
properties of their respective holders. ProJPEG is based in part on the
work of the Independent JPEG Group.

Document published: 10/21/98

Copyright 1998 BoxTop Software, Inc. All Rights Reserved.