Experimental BBS Explossion 3/Experimental BBS Explossion III.iso/os2/imarc101.zip/IMAGEARC.HLP

OS/2 Help File | 1993-04-15 | 22KB | 547 lines

ΓòÉΓòÉΓòÉ 1. Introduction ΓòÉΓòÉΓòÉ

                              Image Archiver v1.01

Image Archiver has been designed to facilitate the process of archiving JPEG
images. The current release has been built upon the Indepent JPEG Group's
version 4a JPEG compression/decompression software. This software currently
supports the following image formats:

o GIF
o PPM/PGM
o Targa

Files to be compressed must be of one of the above types. Decompression of JPEG
files can output to any of the above types also.

The only JPEG file format currently supported is the JFIF format. Support for
the TIFF 6.0 format will probably be added at some future date.


ΓòÉΓòÉΓòÉ 2. Main Dialog ΓòÉΓòÉΓòÉ

The Main Dialog presents top level information and functionality allowing
images to be compressed, decompressed, deleted and viewed. Select one of the
following sections for more information about a specific aspect of this dialog
box.

o JPEG Directory
o Change Dir...
o Deselect
o Delete
o JPEG File List
o Decompress
o Decompress Options...
o View
o View Options...
o Other Directory
o Other File List
o Compress
o Compress Options...


ΓòÉΓòÉΓòÉ 2.1. JPEG Directory ΓòÉΓòÉΓòÉ

This Entry Field shows the current drive and directory where JPEG files are
found.

 This field is Read Only.


ΓòÉΓòÉΓòÉ 2.2. Change Dir... ΓòÉΓòÉΓòÉ

Pressing this button opens up the Change Directory dialog where you select the
drive and directory to find the files for the file list.


ΓòÉΓòÉΓòÉ 2.3. Deselect ΓòÉΓòÉΓòÉ

Selecting this menu item will remove all of the selections from the file list.


ΓòÉΓòÉΓòÉ 2.4. Delete ΓòÉΓòÉΓòÉ

Selecting this menu item will show a message box asking for confirmation to
delete all of the selected files in the file list. Press OK to continue. Press
Cancel to abort the operation.


ΓòÉΓòÉΓòÉ 2.5. JPEG File List ΓòÉΓòÉΓòÉ

This is the pride and joy of Image Archiver. This window presents a list of all
of the JPEG files that were found in the JPEG Directory. Each entry in the list
shows the following important information about the file:

o File Name
o Image Width
o Image Height
o File Size
o Creation Date
o Creation Time

Multiple files can be selected for decompression or deletion with standard
selection techniques.

Clicking mouse button 2 will popup the context menu with all of the opitons
that are available for these files.

Double-Clicking mouse button 1 on one of the files in the list will open that
file for viewing. This is a much quicker way to view pictures that are in the
current directory than by pressing the View button and selecting a file.


ΓòÉΓòÉΓòÉ 2.6. Decompress ΓòÉΓòÉΓòÉ

Selecting this menu item will cause Image Archiver to start decompressing all
of the selected files in the JPEG file list. A progress monitor is provided to
keep track of the process. Pressing Cancel will abort the rest of the
conversion.


ΓòÉΓòÉΓòÉ 2.7. Decompress Options... ΓòÉΓòÉΓòÉ

Selecting this menu item will open up the Decompress Options Dialog dialog.
This dialog does not have to be closed to continue processing.


ΓòÉΓòÉΓòÉ 2.8. View ΓòÉΓòÉΓòÉ

Selecting this menu item will open up a standard file dialog letting you select
a JPEG image to view.


ΓòÉΓòÉΓòÉ 2.9. View Options... ΓòÉΓòÉΓòÉ

Selecting this menu item will open up the View Options Dialog dialog. This
dialog does not have to be closed to continue processing.


ΓòÉΓòÉΓòÉ 2.10. Other Directory ΓòÉΓòÉΓòÉ

This Entry Field shows the current drive and directory where Other supported
files are found.

 This field is Read Only.


ΓòÉΓòÉΓòÉ 2.11. Other File List ΓòÉΓòÉΓòÉ

This is the pride and joy of Image Archiver. This window presents a list of all
of the Other files that were found in the Other Directory. Each entry in the
list shows the following important information about the file:

o File Name
o Image Width
o Image Height
o File Size
o Creation Date
o Creation Time

Multiple files can be selected for compression or deletion with standard
selection techniques.

Clicking mouse button 2 will popup the context menu with all of the opitons
that are available for these files.


ΓòÉΓòÉΓòÉ 2.12. Compress ΓòÉΓòÉΓòÉ

Selecting this menu item will cause Image Archiver to start compressing all of
the selected files in the Other file list. A progress monitor is provided to
keep track of the process. Pressing Cancel will abort the rest of the
conversion.


ΓòÉΓòÉΓòÉ 2.13. Compress Options... ΓòÉΓòÉΓòÉ

Selecting this menu item will open up the Compress Options Dialog dialog. This
dialog does not have to be closed to continue processing.


ΓòÉΓòÉΓòÉ 3. Decompress Options Dialog ΓòÉΓòÉΓòÉ

The Decompress Options dialog box presents all of the settings that are related
to decompressing JPEG files. Select one of the following sections for
information about a specific setting.

o Output Format
o Colors
o Max Memory
o Quantize
o Two-Pass Quant
o Dither
o Cross-Block Smooth
o Grayscale


ΓòÉΓòÉΓòÉ 3.1. Output Format ΓòÉΓòÉΓòÉ

These radio buttons are used to determine the output format of the decompressed
images. There are three image formats to choose from:

o GIF -- Select GIF output.
o PPM/PGM -- Select PGM output if Grayscale is selected, PPM otherwise.
o Targa -- Select Targa output.


ΓòÉΓòÉΓòÉ 3.2. Colors ΓòÉΓòÉΓòÉ

This entry field specifies the number of colors to quantize the JPEG file to.
This number is ignored if Quantize

Valid ranges are 2 to 65536.


ΓòÉΓòÉΓòÉ 3.3. Max Memory ΓòÉΓòÉΓòÉ

This entry field specifies the maximum amount of memory in megabytes to
allocate. If the amount of memory that needs to be allocated exceeds this
value, then temporary files will be created for the excess. Generally, this
value should be kept as high as possible. The process will become slower as the
temporary files become larger.


ΓòÉΓòÉΓòÉ 3.4. Quantize ΓòÉΓòÉΓòÉ

Check this option to quantize the image to the number of colors specified by
the Colors entry field and produce a colormapped output file in the selected
format. If this option is not checked, then the output image will not be
colormapped.

Note that the GIF format requires this option to be checked and the number of
colors to be 256 or less.


ΓòÉΓòÉΓòÉ 3.5. Two-Pass Quant ΓòÉΓòÉΓòÉ

Check this option to quantize the input image in two passes. This method takes
more memory and more time than single pass quantizing, but it can result in
much better image quality.

This option is ignored if Quantize is not checked or if Grayscale is checked.


ΓòÉΓòÉΓòÉ 3.6. Dither ΓòÉΓòÉΓòÉ

Check this option to apply Floyd-Steinberg dithering when quantizing the input
image. On some images this may result in undesirable "grainyness" in the output
image.


ΓòÉΓòÉΓòÉ 3.7. Cross-Block Smooth ΓòÉΓòÉΓòÉ

Check this option to perform cross-block smoothing on the output image. This
process is slow, memory intensive, and seems to only have positive results on
images that were compressed with very low quality settings. In fact, this
option may reduce the quality of standard quality images.


ΓòÉΓòÉΓòÉ 3.8. Grayscale ΓòÉΓòÉΓòÉ

Check this option to force the output image to grayscale regardless of the type
of the input image.


ΓòÉΓòÉΓòÉ 4. View Options Dialog ΓòÉΓòÉΓòÉ

The View Options dialog box presents all of the settings that are related to
viewing JPEG files. Select one of the following sections for information about
a specific setting.

o Size Window to Picture
o Two-Pass Quant
o Dither
o Cross-Block Smooth
o Grayscale
o Max Memory


ΓòÉΓòÉΓòÉ 4.1. Size Window to Picture ΓòÉΓòÉΓòÉ

Check this option to optimally size the window to the size of the image being
viewed. This causes the window to be sized no larger than the screen if the
image is too big to fit. The window is also centered on the screen. If this
options is not checked, then the window will be restored to it's last size and
position.


ΓòÉΓòÉΓòÉ 4.2. Two-Pass Quant ΓòÉΓòÉΓòÉ

Check this option to quantize the input image in two passes. This method takes
more memory and more time than single pass quantizing, but it can result in
much better image quality.

This option is ignored if Grayscale is checked.


ΓòÉΓòÉΓòÉ 4.3. Dither ΓòÉΓòÉΓòÉ

Check this option to apply Floyd-Steinberg dithering when quantizing the input
image. On some images this may result in undesirable "grainyness" in the output
image.


ΓòÉΓòÉΓòÉ 4.4. Cross-Block Smooth ΓòÉΓòÉΓòÉ

Check this option to perform cross-block smoothing on the output image. This
process is slow, memory intensive, and seems to only have positive results on
images that were compressed with very low quality settings. In fact, this
option may reduce the quality of standard quality images.


ΓòÉΓòÉΓòÉ 4.5. Grayscale ΓòÉΓòÉΓòÉ

Check this option to force the output image to grayscale regardless of the type
of the input image. Checking this option provides a way to quickly preview an
image as no slow quantizing process takes place.


ΓòÉΓòÉΓòÉ 4.6. Max Memory ΓòÉΓòÉΓòÉ

This entry field specifies the maximum amount of memory in megabytes to
allocate. If the amount of memory that needs to be allocated exceeds this
value, then temporary files will be created for the excess. Generally, this
value should be kept as high as possible. The process will become slower as the
temporary files become larger.


ΓòÉΓòÉΓòÉ 5. Compress Options Dialog ΓòÉΓòÉΓòÉ

The Compress Options dialog box presents all of the settings that are related
to compressing JPEG files. Select one of the following sections for information
about a specific setting.

o Quality
o Restart
o Smooth
o Max Memory
o Grayscale
o Optimize
o Force Targa Input
o Add Comment


ΓòÉΓòÉΓòÉ 5.1. Quality ΓòÉΓòÉΓòÉ

This entry field specifies the quality of compression that is desired. The
default and recommend value is 75. This results in very good compression and
minimal loss in the compressed image.

The quality setting lets you trade off compressed file size against quality of
the reconstructed image: the higher the quality setting, the larger the JPEG
file, and the closer the output image will be to the original input. Normally
you want to use the lowest quality setting (smallest file) that decompresses
into something visually indistinguishable from the original image. For this
purpose the quality setting should be between 50 and 95; the default of 75 is
often about right. If you see defects at -quality 75, then go up 5 or 10 counts
at a time until you are happy with the output image. (The optimal setting will
vary from one image to another.)

A quality setting of 100 will generate a quantization table of all 1's,
eliminating loss in the quantization step (but there is still information loss
in subsampling, as well as roundoff error). This setting is mainly of interest
for experimental purposes. Quality values above about 95 are NOT recommended
for normal use; the compressed file size goes up dramatically for hardly any
gain in output image quality.

In the other direction, quality values below 50 will produce very small files
of low image quality. Settings around 5 to 10 might be useful in preparing an
index of a large image library, for example. Try -quality 2 (or so) for some
amusing Cubist effects. (Note: quality values below about 25 generate 2-byte
quantization tables, which are considered optional in the JPEG standard. Some
commercial JPEG programs may be unable to decode the resulting file.)


ΓòÉΓòÉΓòÉ 5.2. Restart ΓòÉΓòÉΓòÉ

The restart option inserts extra markers that allow a JPEG decoder to
resynchronize after a transmission error. Without restart markers, any damage
to a compressed file will usually ruin the image from the point of the error to
the end of the image; with restart markers, the damage is usually confined to
the portion of the image up to the next restart marker. Of course, the restart
markers occupy extra space. A restart value of 1 is recommended by the
Independent JPEG Group for images that will be transmitted across unreliable
networks such as Usenet.


ΓòÉΓòÉΓòÉ 5.3. Smooth ΓòÉΓòÉΓòÉ

The smooth option filters the input to eliminate fine-scale noise. This is
often useful when converting GIF files to JPEG: a moderate smoothing factor of
10 to 50 gets rid of dithering patterns in the input file, resulting in a
smaller JPEG file and a better-looking image. Too large a smoothing factor will
visibly blur the image, however.


ΓòÉΓòÉΓòÉ 5.4. Max Memory ΓòÉΓòÉΓòÉ

This entry field specifies the maximum amount of memory in megabytes to
allocate. If the amount of memory that needs to be allocated exceeds this
value, then temporary files will be created for the excess. Generally, this
value should be kept as high as possible. The process will become slower as the
temporary files become larger.


ΓòÉΓòÉΓòÉ 5.5. Grayscale ΓòÉΓòÉΓòÉ

Check this option to produce a grayscale JPEG file from a color input file. You
must check this option if the input file is a grayscale GIF because the
software can't distinguish a grayscale GIF from a color GIF. Checking this will
produce a JPEG file that is smaller and quicker to decompress.


ΓòÉΓòÉΓòÉ 5.6. Optimize ΓòÉΓòÉΓòÉ

Check this option to perform optimization of the entropy encoding parameters.
This usually makes the resulting JPEG file a little smaller, but it takes more
time and a lot more memory. This setting does not affect the image quality or
the decompression time of the JPEG file produced.


ΓòÉΓòÉΓòÉ 5.7. Force Targa Input ΓòÉΓòÉΓòÉ

Check this option to force the input files to be treated as Targa files. This
is useful when the Targa file has an "identification" field because that field
is not automatically recognized by the software. Most Targa files should not
need this setting.


ΓòÉΓòÉΓòÉ 5.8. Add Comment ΓòÉΓòÉΓòÉ

Check this option to cause Image Archiver to prompt you for a comment to be
inserted into any JPEG file that it is creating.

This feature is only available in the registered version.


ΓòÉΓòÉΓòÉ 6. Viewing Window ΓòÉΓòÉΓòÉ

This window allows the image to be scrolled, scaled to the size of the window,
and zoomed in and out. The View menu option provides access to the
functionality available with the mouse. Keyboard accelerators are also
available. Select one of the following sections for more specific information.

o View Menu and keyboard commands
o Zooming with the mouse.


ΓòÉΓòÉΓòÉ 6.1. View Menu and Keyboard Commands ΓòÉΓòÉΓòÉ

In the current OS/2 2.1 beta, there are some significant bugs in the Palette
Manager. First of all, any part of the image that is over-written with a menu
or a dialog box will not be redrawn with the correct colors on Trident or
ET4000 video cards. I believe that only the XGA palette manager works properly.
(I'm not too sure about that one.) The other problem is that the image will
only be properly rendered if it is drawn at it's actual size. This bug kind of
limits the use of zooming and scaling, but hopefully the bug will be fixed with
the release of 2.1 GA.

Select one of the following selections for more specific information.

o Zoom In (+)
o Zoom Out (-)
o Actual Size (=)
o Scale to Window (F8)
o Size to Image (F9)
o Refresh (F10)


ΓòÉΓòÉΓòÉ 6.1.1. Zoom In (+) ΓòÉΓòÉΓòÉ

Select this menu item or press the + key to zoom in on the image by another
25%. The image starts out at 100% zoom. Repeatedly selecting this item will
zoom in on the image in 25% increments, first to 125, then to 150, then to 175,
etc. There is no zoom in limit.

BETA  The image is reset to the top left corner each time this is pressed.


ΓòÉΓòÉΓòÉ 6.1.2. Zoom Out (-) ΓòÉΓòÉΓòÉ

Select this menu item or press the - key to zoom out of the image by another
25%. The image starts out at 100% zoom. Repeatedly selecting this item will
zoom out from the image in 25% increments, first to 75, then to 50, then to 25.
25 percent is the zoom out limit.

BETA  The image is reset to the top left corner each time this is pressed.


ΓòÉΓòÉΓòÉ 6.1.3. Actual Size (=) ΓòÉΓòÉΓòÉ

Select this menu item to return the image to its actual size. This returns the
image to 100% zoom.


ΓòÉΓòÉΓòÉ 6.1.4. Scale to Window (F8) ΓòÉΓòÉΓòÉ

Select this menu item to scale the image so that it fits entirely with in the
window. The image's aspect ratio is kept, both the width and height of the
image is scale by the same factor.


ΓòÉΓòÉΓòÉ 6.1.5. Size to Image (F9) ΓòÉΓòÉΓòÉ

Select this menu item to size the window to fit as much of the picture within
it as it can. If the picture is larger than the maximum size of the window,
then the window is set to the largest size possible, still keeping all borders
on the screen. The window is not maximized. This can be set to happen
automatically with the Size Window to Picture option.


ΓòÉΓòÉΓòÉ 6.1.6. Refresh (F10) ΓòÉΓòÉΓòÉ

Select this menu item to refresh the image. This option is required because of
the few significant bugs in the 2.1 beta's Palette Manager.


ΓòÉΓòÉΓòÉ 6.2. Zooming with the mouse ΓòÉΓòÉΓòÉ

Image Archiver provides a very powerful method of zooming into an arbitrary
area of an image. Follow thses simple instructions to zoom in to any part of
the image to any detail level.

 1. Move the mouse pointer to approximately the top left corner of the part of
    the image that you wish to zoom into.
 2. Press and hold down mouse button 1.
 3. Continue to hold down mouse button 1 and drag the mouse pointer to
    approxiamtely the bottom right of the area. A tracking rectangle will
    follow the pointer showing the area that will be zoomed into.
 4. Release mouse button 1 to see the selected area.

This option only works when the image is being viewed in it's Actual Size.

BETA  There are still a few bugs in this zooming system. I recommend selecting
Actual Size and Size to Image before attempting any arbitrary zoom operation
with the mouse.


ΓòÉΓòÉΓòÉ 7. Acknowledgements ΓòÉΓòÉΓòÉ

Image Archiver is based in part on the work of the Independent JPEG Group. This
work includes both code and documentation.

I'd like to pass on my thanks to Tom Lane and the others of IJG on the work
they have done to provide very functional code to the rest of us in the
programming world. Good job people!

I'd also like to thank the following people for their contributions to my
sanity:

o Guy Scharf, president of Software Architects.

  Thanks for the wonderful and very helpful articles on both container and
  slider controls.

o Peter Nielsen, author of PMView (check it out, it's a great viewer).

  Thanks for help with the Palette Manager and all it's wonderful little quirks
  in the OS/2 2.1 beta incarnation.

o Everyone else on the Internet.

  Thanks for all the answered questions, sample code, moral support, etc. Image
  Archiver wouldn't exist without you all.

"The Graphics Interchange Format(c) is the Copyright property of CompuServe
Incorporated. GIF(sm) is a Service Mark property of CompuServe Incorporated."