AWeb JFIF plugin
General
The awebjfif plugin for AWeb allows you to view all JFIF images.
Features include:
- Optional progressive display of loading images
- Support for scaling
- Support for CyberGraphics
Installation
Follow these steps to install the AWeb JFIF plugin.
-
Run the supplied Installer script. It will copy the necessary files to a
drawer
AWebPlugins
in the drawer where the AWeb program is
located.
The installer script might ask you for a location to store temporary swap
files during decoding of large images. You should select a drawer on your
hard disk.
-
Manual Installation
If, for some reason, you don't want to install the plugin automatically, you
can install it by hand.
-
Copy the file named
awebjfif.awebplugin
to a location of your
choice. The recommended location for plugins like this is a drawer
AWebPlugins
in the drawer where the AWeb program is located.
- Select a drawer on your hard disk for the temporary swap files. These files
may be needed during decoding of large images. Add the following assign to
your
S:User-Startup
file if it isn't already there:
assign JPEGTMP: swap_drawer
where swap_drawer is the drawer you selected.
-
Start AWeb, open the browser settings and bring up the Viewers page.
Select the entry for MIME type
IMAGE/JPEG
and change the following
settings:
- Action: "AWeb Plugin (A)"
- Name: the location where you copied the file
awebjfif.awebplugin
- Arguments: leave blank or supply optional parameters, see below
-
Don't forget to save your settings.
Repeat steps 3 and 4 for the MIME type IMAGE/PJPEG
The awebjfif plugin supports some optional parameters. You can type the chosen
parameters in the "Arguments:" field of the settings window. Separate the
parameters by a comma or space, if you specify more than one.
PROGRESS=0|number
- Specifies the number of image scan lines to decode before the display is
updated. A higher number is faster but results in chunkier building of the
image. PROGRESS=1 gives the smoothest progressive display but is relatively
slow. The default value is 4, which is a good compromise between speed and
visual attractiveness.
If you specify PROGRESS=0, progressive display is disabled. The image is
not displayed until decoding is ready.
MULTIPASS=0|1
- Specifies if progressive JPEG images should be rendered progressively.
MULTIPASS=1 (the default) will display progressive JPEGs in multiple passes,
each with increasing quality.
Use MULTIPASS=0 to disable rendering in multiple passes, and only display
the final image. This may be faster when reading from fast connections or
from local files.
DITHER=0|1|2
- A number specifying the dither mode if colourmapped images are generated.
This option takes only effect on screens with 256 colours or less. On
CyberGraphics screens with more than 256 colours, true colour images are
produced and no dithering is performed.
The number specifies the type of dithering as follows:
number | dither mode
|
0 | No dithering (fast but low quality)
|
1 | Ordered (compromise between no dithering and Floyd-Steinberg)
|
2 | Floyd-Steinberg (best quality but slow).
This is the default.
|
GRAYSCALE
- Produce grayscale images. This is faster than colour images.
MAXMEM=number
- Specifies the maximum amount of scratch memory (in kB) to be used for the decoding
process of each image. Large images may take quite a lot of memory during
decoding. If an image needs more memory than the specified maximum, a virtual
memory system is used. After the image has been decoded, the scratch memory
is released, even if the image is still displayed.
Default for this parameter is 1024 (= 1 megabyte). Note that the maximum
is used on a per-image basis, not for all images together.
LOWPRI
- The LOWPRI argument will run the decoder at a lower priority than default.
If you are using your Amiga for other tasks while AWeb is downloading images,
this feature helps you to keep the GUI responsive when many images are being
decoded.
However, if you are running CPU intensive tasks this argument could stop
images from being processed alltogether.
Note that the LOWPRI argument might not be effective when you use a custom task
scheduler like Executive. Use task name "AWebJFIF decoder" to configure the
decoder task in custom schedulers.
DEBUG=0|1
- The DEBUG argument switches on or off output of errors and warnings from the
underlying JPEG Library to standard out.
DEBUG=0 no debug output (default)
DEBUG=1 output debug info.
Support
This distribution of AWeb comes with no support, however the AWeb Mailing list has many users and you are encouraged to subscribe if you haven't aleady done so.
Disclaimer
This software is provided "as is". No warranties are made, either
expressed or implied, with respect to reliability, quality, performance,
or operation of this software. The use of this program is at your own risk.
Yvon Rozijn assumes no responsibility or liability for any damage or
losses resulting from the use of this software, even if advised of the
possibility of such damage or loss.
Copyright
Copyright © 2002-2007 by the respective contributers of The AWeb Open Source Project. All rights reserved.
Any code or files that remain in their original, unmodified form are
Copyright © 2002 by Tom Parker, and copyright © 1998-2000 by Yvon Rozijn. All rights reserved.
It uses code from the JPEG library that was written by the Independent JPEG Group (IJG).
History
awebjfif.awebplugin 1.10 (14-01-2002)
- Removed low memory bug
- Removed minor bug with LOWPRI option
- Fixed and compiled by Tom Parker
awebjfif.awebplugin 1.9 (1-12-2000)
- Added support for scaling after completion, necessary for percentage scaling.
awebjfif.awebplugin 1.8 (5-9-1999)
- Cleaned up the code a bit.
awebjfif.awebplugin 1.6 (19-10-1998)
- Added support for proportional scaling (only one of WIDTH and HEIGHT specified).
- Added MULTIPASS argument.
awebjfif.awebplugin 1.3 (01-03-1998)
awebjfif.awebplugin 1.2 (25-02-1998)
- Removed possible decoder stalls.
- Much faster progressive display of scaled images.
awebjfif.awebplugin 1.1 (14-02-1998)
- Didn't support progressive JPEGs (used old library version)
- Didn't support grayscale JPEGs.
awebjfif.awebplugin 1.0 (11-02-1998)