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MacWorld 1998 February
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Macworld (1998-02).dmg
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Comms & Internet
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A Smaller GIF 1.07 (680x0)
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Reference Manual
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1997-06-05
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This is a very brief reference manual for A Smaller GIF†. It can be found online at
http://www.peda.com/smaller/man.html. The manual has two sections. The first
section describes the menus; the second section describes the windows.
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We begin with an overview of the menus available while using A Smaller GIF.
Apple Menu
* About A Smaller GIF... displays the start-up screen. It may be
dismissed by pressing any key. The start-up screen shows the program's
version number on the left and the registered user's name on the right.
File Menu
* Open... allows you to open an animated GIF to work with. After opening
a file, three windows will open (a preview window, an animation
controls window, and a frame controls window). The windows are
described in the Windows section of this manual. An additional work
window (the range controls window) may be opened via Range Controls...
in the Animation menu.
* Close Window closes the foremost window. Closing any of the windows for
a particular animated GIF will close all of the windows associated with
that animated GIF.
* Save saves the current document after trying to minimize the amount of
disk space the animation uses. A Smaller GIF can reduce the amount of
space an animation uses without changing its appearance in any way, as
GIFs are stored using a lossless compression format. Many of the GIF
utilities available do not maximally compress GIF files when they are
saved. Even A Smaller GIF is not guaranteed to fully compress a GIF
file. Currently, the program uses a number of techniques to reduce the
size of the resulting GIF file. Later versions of this program may
incorporate additional compression techniques. Some techniques may
produce files that are not compatible with viewers that do not fully
implement the GIF standard - you have some control over the techniques
employed via the preferences window.
* Save As... is similar to Save, but allows you to save the file using a
new name, so that you may keep your original file intact.
* Test Compression compresses the GIF file without actually saving it.
After compression, it will report the file size that would have been
acheived if the file was actually saved.
* Register... is used to register the program. For more registration
information, please see our registration page.
* Preferences... opens the preferences window, which allows you to
control the compression techniques used. You may also edit your own
standard GIF comment by using the preferences. See the section on
preferences for more information.
* Quit exits the program.
Edit Menu
The edit menu allows you to cut, copy, and paste text into the various text
fields used.
Animation Menu
The animation menu is available after you have opened an animation.
* Add Standard Comment prepends the exit comment with your standard
comment. You may modify your standard comment via the preferences
window.
* Remove All Comments removes all GIF comments from the animation.
* Standardize Comments first removes all GIF comments from the animation,
and then adds your standard comment.
* Deinterlace All Frames deinterlaces all of the frames of the animation.
On many platforms, Netscape Navigator (versions 2 and 3) flickers
considerably when displaying the first frame of an animated GIF which
is interlaced. Subsequent interlaced frames don't cause flicker, but do
slow updating. On both the Macintosh and Windows platforms, Microsoft
Internet Explorer (version 3) handles interlaced animated GIFs well.
* Range Controls... opens a range controls window for the animation. The
range controls window allows you to easily apply operations to every
frame within a selected range of frames.
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We illustrate the remainder of the program by discussing what happens when
you open the provided "GrafEq Ad.gif" file that is supplied as part of the
download package. The file has already been processed by a utility which
claims to shrink your GIF files.
Preview Window
The preview window, entitled "GrafEq Ad.gif Preview", displays a preview of
the animated GIF. If you enlarge the window, you will see the entire window
title. The preview image will be centered within the larger window, and
surrounded by the GIF's background colour.
The keyboard's arrow keys may be used to navigate, as described below:
* Press the right arrow key to advance the preview by one frame. Hold the
right arrow key down to fast-forward through the animation.
* Press the left arrow key to rewind the preview by one frame. Hold the
left arrow key down to rewind through the animation.
* Press the down arrow key to play the animation forward, at normal
speed. Press the key again to fast-forward through the animation.
* Press the up arrow key to play the animation backward, at normal speed.
Press the key again to repidly rewind through the animation.
* Press the space bar to toggle preview playback. If the preview is
playing, the space bar stops the preview. If the preview isn't playing,
the space bar starts playing the preview forward, at normal speed.
* Press the escape key to stop the preview from playing.
If the preview reaches the end of the animation while playing forward, it
will resume from the beginning. If the preview reaches the beginning while
playing backward, it will resume from the end.
Animation Controls Window
The animation controls window, entitled "GrafEq Ad.gif Animation Controls",
is used to control the overall animation. Although you often can't see the
entire title, the window's visual appearance sets it apart from the other
windows.
* Size: 140x60 (6.1K) displays the size of the animation. In this case,
it is 140 pixels wide, 60 pixels high, and uses approximately 6.1
kilobytes of disk space.
* 31 Frames (0:07.20) displays the length of the animation. In this case,
it contains 31 frames. If the animation is played at normal speed, on a
machine capable of playing the animation at normal speed, it will last
7.2 seconds.
* Loop forever controls the looping aspects of the animation. This
animation is set to loop forever. Other possibilities include playing
once, or looping a fixed number of times, from once to 65,535 times.
* 24 colours displays the number of colours used in the animation.
* Background Colour FFFFFF displays, visually and textually, the
background colour of the animation. Web browsers tend to ignore this,
and opt to use the web page background instead of the background
specified here. As the background given here is used in the preview,
this control allows you to see the effects of different page
backgrounds. The textual description is given using HTML syntax - the
colour is given as <red><green><blue>, with each component given as a
two digit hexadecimal number.
* Starting Comment displays the GIF comment(s) that precede the frames of
the animation. You may edit the comment. Normally, one chooses to put
comments after the animation frames, by using the next control.
Starting comments will delay the arrival of the first frame.
* Ending Comment displays the GIF comment(s) that follow the frames of
the animation. You may edit the comment.
Frame Controls Window
The frame controls window, entitled "GrafEq Ad.gif Frame Controls", is used
to control the current frame of the animation. Although you often can't see
the entire title, the window's visual appearance sets it apart from the
other windows.
* Frame 1 0:00.00 identifies the current frame. In this case, the current
frame is the first frame, which also starts at 0 seconds into the
animation. You may jump to any frame in the animation by entering a
frame number.
* The frame slider appears next. It visually displays your position in
the animation. You may position yourself to any frame by dragging the
thumb with the mouse.
* The seven playback controls are displayed next. The edgemost controls
rapidly rewind and fast-forward the preview through the animation. The
next pair plays the animation, at normal speed, backwards and forwards.
The innermost pair rewind and advance the preview through the animation
one frame at a time. The center control halts automatic playback.
* Duration 0:01.00 controls the duration of the current frame. In this
case, the current frame lasts 1 second.
* User Input specifies if the user, by giving some sort of input, may
cause the animation viewer to advance to the next frame before this
frame's duration has expired. If checked, and the user gives input
while this frame is displayed, the viewer should immediately advance to
the next frame. If this frame has a duration of zero seconds and the
control is checked, the viewer should not advance until user input is
given. A Smaller GIF ignores this feature of GIF animations, as do most
other viewers.
* Interlaced controls whether the current frame is interlaced.
* Comment shows the comment(s) that immediately precede the current
frame. Normally, comments are put at the end of the animation by using
the Exit Comment control in the animation controls window.
Range Controls Window
The range controls window, entitled "GrafEq Ad.gif Range Controls", allows
you to work with frames as a group. With this window, you may apply an
operation to every frame within a range of frames without manually
performing the operation on each frame yourself. Although you often can't
see the entire title, the window's visual appearance sets it apart from the
other windows.
The range controls window can be in one of several modes. The individual
modes will be discussed later. We will first focus on the controls that are
common to all modes.
* Scale Durations is a popup menu that lets you control which mode the
window is in.
* Frames 1 to 31 (inclusive) displays the selected range of frames. You
may select a new range of frames by either typing in a new frame range
or using the slider below. The arrow keys may also be used to select a
range of frames: the left and right arrow keys change the selection's
lower endpoint, while the up and down arrow keys change the selection's
upper endpoint. Whenever an action is applied using this window, it
will only affect the frames within the selected range of frames.
We will now go over the controls in each of the available modes.
Scale Durations
This mode allows you to change the duration of many frames at once. The
duration of each frame in the range is multiplied by the specified
scaling factor.
o Scaling Factor: 1.00 specifies the scaling factor to be used. You
can enter a new scaling factor or select a scaling factor between
0.1 (ten times faster) and 10.0 (ten times slower) by using the
slider below.
o More Choices lets you have more control over the process. Click
this button to reveal more controls.
o Scale scales the duration of the selected frames.
o After Scaling: specifies the minimum and maximum duration of each
frame, after scaling has been applied. This control is shown by
selecting more choices. To make all of the selected frames have
the same duration, enter the same value for minimum and maximum
duration. A non-zero minimum duration is advised, as a frame with
zero duration may not be displayed by some viewers.
o Fewer Choices removes the advanced controls from display, after
reseting them to their default values.
Remove Comments
This mode allows you to remove comments from a range of frames.
o Remove Comments removes all comments from the selected range of
frames.
Deinterlace
This mode allows you to deinterlace a range of frames.
o Deinterlace deinterlaces all of the selected frames.
Preferences Window
The preferences window, opened by selecting Preferences (under File), is
used to
* control which GIF compression techniques are tried, as well as to
* edit your standard comment.
The popup control in the top left corner of the window selects which
preferences you wish to review. Preferences are stored on disk in the
registration file. Comments on each of the available preferences follow:
* GIF Optimization
The GIF optimization controls allow you to trade off compatibility
against file size. Maximum compression is usually achieved by keeping
all controls checked and to pick transparencies from an ultralow band.
For good compatility with browsers you can uncheck Omit frame
terminators, uncheck Use a small rectangle for the first frame, and choose
transparencies from the superlow band. Doing so will normally increase file
size slightly and keep compatibility with older versions of the common
browsers. To see expected compatibility, click on the Compatiblity... button
to bring up an interactive window which will let you see the interaction
between the compression options and browser compatibility. Small, simple
animations are more generally compatible than long, complex animations
since small, simple animations are less likely to expose a bug in a
browser.
We would like to thank users for keeping us informed of bugs in the
browsers out there so we can add ways to avoid the problems that may
occur. The good news is that with each release, the browsers are
usually getting better at displaying animated GIFs.
o Omit frame terminators specifies whether frame terminators may be
omitted. Most GIF viewers ignore frame terminators and opt to
determine the end of a frame by counting the number of pixels
decoded. Viewers are forced to do this since a moderate number of
GIFs do not include frame terminators. With this option selected,
the files are slightly smaller, but do not follow the GIF
specification strictly. Internet Explorer for Windows (and other
Windows-based Microsoft software) requires frame terminators.
o Exclude (0,0) from frame rectangle specifies whether the top left
corner of encoded frames must be the top left corner of the
animation. A Smaller GIF only encodes differences between frames,
so the upper left corner is often not included by default.
Checking this will generate smaller GIFs. Produced GIFs will not
be compatible with version 2 of Internet Explorer for the
Macintosh if this control is checked.
o Use interframe transparency specifies whether transparency may be
used to encode pixels that do not change from one frame to the
next. Many GIF utilities do not deal with transparency very well,
so unchecking this may allow you to edit the GIF before putting a
final version up for people to view.
As an example, GifBuilder for the Macintosh will display, when
looking at a particular frame of an animation, transparent areas
as being transparent (rather than taking into account the previous
frame, as a simple viewer would). If you were to play the
animation back in GifBuilder however, the animation will be
properly displayed. Many other GIF utilities behave similarly.
o Pick a transparency index from the ultralow A band partially
specifies which index should be used for transparency. This
control is provided so that you may work around display bugs in
various browsers. The general rule is that the higher bands will
produces larger GIFs. Netscape Navigator 2 and 3 for the Macintosh
both have some trouble displaying GIFs that use transparency.
Picking transparency indices from the superlow band (which
increases file size slightly) will usually avoid such problems for
GIFs that use transparency mainly for interframe compression. A
higher band is sometimes needed for GIFs that use transparency
visually (so that you may see moving objects against a web page's
background). There is a rumour going around the Netscape Navigator
3 for the Macintosh cannot display such animations (regardless of
which tool is used to create them), but we have had success with
such animations by using transparencies from higher bands.
o Compatibility... opens up the Compatibility window, which lets you
interactively see the interplay between the compression options
and browser compatibility. With the compatibility window, you may
control the compression options indirectly by controlling the
compatibility directly (or vice-versa). Note that the
compatibility reported is pessimistic, as it is for long, complex
GIFs. Small, simple GIFs will likely be compatible regardless of
the compression options, as such animations are unlikely to expose
bugs in the browser. The estimated audience figure comes from
statistics gathered from the www.peda.com web site. More Info...
displays information regarding the Compatibility window.
* GIF Comments
o Standard GIF Comment shows your standard GIF comment. You may
quickly add your standard comment to an animation by selecting Add
Standard Comment from the Animation menu.
The default comment is "Shrunk by NAME on DATE, using A Smaller
GIF vVERSION."
+ "NAME" expands to the registered user's name,
+ "DATE" expands to the current date, and
+ "VERSION" expands to the current version of the program.
* Startup
o When appropriate, show depth warning on startup controls whether A
Smaller GIF will warn you when you start up on a display with 256
or fewer colours. If checked, A Smaller GIF will warn you that
animation previews may be inaccurate with the current display
settings, and that image processing is not affected.
For more information visit the program’s web page at http://www.peda.com/smaller/.
______________________
†The Graphics Interchange Format© is the Copyright property of Compuserve Incorporated.
GIF(sm) is a Service Mark property of Compuserve Incorporated.
†A Smaller GIF™ is a trademark of Pedagoguery Software.
†Netscape Navigator is a trademark of Netscape Communications Corporation.
†Internet Explorer is a trademark of Microsoft.
All other displayed trademarks are the property of their respective holders.