RISC DISC 3/RISC_DISC_3.iso/resources/jpeg/_imagebank/_help

Text File | 1996-10-30 | 13.0 KB | 381 lines

ImageBank
=========

ImageBank is a simple RISC OS compliant application to package up a number
of JPEG images with browser + cataloguer + compressor + decompressor.

An image can be:-

 - added to the archive by dropping on the browser window.
 - exported by dragging from the browser window.
 - decompressed in to a window by double-clicking on it.
 - deleted from the archive.
 - renamed.

Non-bitmap images can also be added to the archive in the usual manner.
They will be compressed using the Squash module (typically giving a 2:1
compression ratio) rater than JPEG and so will suffer no degradation in
quality.

Currently Draw files are the only non-bitmap format supported.

In addition a fuller description of the image can be saved and displayed
along with the browse image.

Online help is provided via the Acorn !Help application.

This application will only run on RISCOS 3.10 or later.

This software is based in part on the work of the Independent JPEG Group.
Version 4 release 10-Dec-92.

The fast JPEG decompression code was implemented by W.Stoye of
Acorn Computers Ltd.

StrongARM
=========

This is a special StrongARM release of ImageBank. It can be used to
view other !ImageBank archives without having to move directories or
set paths. Having run it just double-click on another !Imagebank
and its contents will be loaded.

If you click on a second !Imagebank then a second copy of this new
Imagebank will be run to display its files.

If you wish to disable this behaviour then hold down the control key
whilst double-clickkng on the new copy of !ImageBank and it will run
as usual.

ICON BAR
========

Clicking on the ImageBank icon will open the root browser window.

Dragging a JPEG file to the icon will decompress it and display it in a
window (but won't add it to the catalogue).

MENU

 - Info
Opens a standard application information box.

 - Choices.Use fonts
If this is selected then the Homerton.Medium font will be used in the
browser windows, otherwise the system font will be used.

 - Choices.Browse size
This allows you to set the maximum size of the browse images created when a
new image is imported.

 - Choices.Quality
This allows you to choose the quality level at which to compress. 100 is the
highest value, 25 the practical lowest. A value of 75 usually gives good
compression without any degradation being noticeable.

 - Choices.Optimise entropy
If this is selected then extra time will be taken in compression. It will
give an identical picture when decompressed but the compressed file size
will be slightly smaller.

 - Choices.Input Smoothing
If you are importing dithered 256 colour sprites then this option can be
used to smooth out the effect of the dithering before compression, improving
the compression factor. Sensible values are from 10-50. It shouldn't be used
when importing Clear files or true-colour sprites. To use you should set a
value in the dialogue box and ensure that the menu entry is ticked.

 - Choices.Fast decompress
When enabled the fast decompression code is used. When in this mode optimised
sprite output is not available. If you require optimised sprites or ImageBank
does not appear to recognise a JPEG file then try disabling this option.

 - Choices.Block smoothing
This smooths the output when a file is decompressed. It can improve picture
quality when an image was compressed with a low quality level (ie below 50).
It shouldn't be used with higher quality images as may make the image worse.

 - Choices.Table matching
By default, when finding the best colour for 256 colour standard palette
sprites, an algorithmic approach is used. This gives very good results but
takes quite a while (longer than the actual time to decompress the image).
If this option is enabled then the best colour is found by a table lookup,
this is much faster but gives a slightly lower quality final image.

 - Save choices
This saves the above choices plus some defaults for the browser windows
(such as save type and sprite type).

BROWSER
=======

Operation of the browser windows is closely modelled on that of the filer.
So

 - Click SELECT
      to select a single item.
 - Click ADJUST
      to toggle an item in and out of the selection.

 - Double click SELECT
      on an image to decompress it and display it in a window.
      on a directory to open a browser onto it.
 - Double click ADJUST
      as SELECT but closes the browser window afterwards.

 - SHIFT Double click SELECT
      on a directory to close the directory browser.
 - CTRL Double click SELECT
      to open the info window for an object.

 - Click ADJUST on the close icon to close the browser and open its parent.
 - SHIFT click ADJUST on the close icon to open the parent only.

 - Drag SELECT
      between browser windows moves the selection from one browser to the
other. Note that directories cannot be moved, however you can create a new
directory (with the same as necessary) in the destination browser and copy
all the images.
      to a directory display or to another application will attempt to save
the image to disc or to the application. The filetype used will be the one
shown ticked in the Save submenu, and in the case of sprites the sprite type
used will be that shown ticked in the Sprite submenu.

 - Drag ADJUST does the same as above but closes the browser wdinow
afterwards.

Files can be dragged to the browser window also. Acceptable types are JPEG,
Sprite (8 bit and above), Clear and Draw file.

If a JPEG file is dropped onto a browser window it ic copied into the
catalogue store and decompressed to create a browse sprite which is then
displayed in the browser.

If a Sprite or Clear file is dropped on a browser window then they will be
compressed (using the options set in the iconbar Choices submenu) and a
browse sprite created.

If a Draw file is dropped on then it is compressed using the Squash module
and a browse sprite created.

After decompression or compression the Info window will be opened so that
you can enter a longer description of the image.

Note that if multiple files are dropped onto the browser window only the
first one will be added to the archive. If you hold down the control key
whilst the images are compressing then the Info window will not be popped
up and multiple image can be compressed in one go.

MENU

 - Display.Icons
 - Display.Full info
Choose between two display methods as for a standard directory display.

 - Display.Sort by name
 - Display.Sort by size
 - Display.Sort by date
Choose the sort method for this browser.

 - Image.Save JPEG
This will save out the compressed image.

 - Image.Save sprite
This leads to a further submenu giving the five different sprite types that
can be saved. They are described in more detail below. Clicking on one of
the menu items will select that as the default sprite save type.

 - Image.Save clear
This will decompress the image to a Clear file.

Clicking on any of the save menu items will select that type as the default
filetype to be used when saving images by dragging directly out of the
browser window.

 - Image.Save draw
If the image dropped in was a draw file then use this entry to save out as
a draw file.

 - Image.Save read only
This will save a copy of the ImageBank application containing the selected
images. This saved version will be read only and may be freely given away
as long as it is not further modified in any way.

 - Image.Rename
Change the 10 character name displayed in Icon view and used as a default
when saving.

 - Image.Info
This leads to a dialogue box giving full information about the image or
directory and allowing the long description to be altered.

 - Edit.Copy
Copy a selected image to the clipboard. From here it may be imported by any
application that supports the clipboard protocol. The image can be exported
as a JPEG, Sprite or Clear file depending on what the receiving application
supports. If a sprite file is exported then the exact type of sprite file is
determined by what is ticked in the sprite save submenu.

 - Edit.Paste
Import an image from the clipboard.

 - Edit.Delete
This will delete a selection of images and directories. Note directories can
only be deleted when empty.

 - Edit.Select all
Select all objects in the browser.

 - Edit.Clear selection
Clear the selection.

 - New directory
This will create a new directory in the browser with the given short name.

 - Open parent
This will open the parent of this browser.


IMPORT
======

Import options.

               Bitmap  ptr / jpeg / squash
  JPEG           yes    opt   opt      no
  Sprite/Clear   yes    opt   opt     opt
  DrawFile        no    opt   no      opt
  others         opt  y opt   opt     opt
                      n opt   no      yes


DISPLAY
=======

 - Save image
Saves the image as displayed as a sprite file.

 - Zoom
Allows you to zoom in and out of the image.

Click ADJUST on close icon to open parent browser (or filer window if
displaying a JPEG file dropped on the iconbar) as with browser windows.

Note that the sprite displayed in this window is not affected by the default
sprite type set in the menus. It will either be a standard palette 256
colour, 32 thousand colour or 16 million colour sprite depending on the
current screen mode.

CATALOGUE INFORMATION
=====================

Information on each image stored in the catalogue is as follows

 - Original filename of image imported (or task that exported it if it was
saved directly from another application).
 - Time and date image was imported.
 - Dimensions of image.
 - Resolution of image (pixels per inch). Note that JFIF files don't store
any resolution or aspect ratio information. This means that a file created
from a sprite with non-square pixels (eg MODE 15) will appear squashed
vertically if decompressed by another application that didn't know this.
ImageBank stores this information so that it can recreate the appropriate
sprite type.
 - Short name for Icon displays and saving.
 - Long description for Full info displays.
 - Quality factor used in compression. Again this value is not stored in a
JFIF file so it is only known from images compressed by ImageBank.

MEMORY
------

When compressing decompressing images, memory is temporarily allocated from
the Wimp Free pool. If there is not enough then temporary files are created
in a location given by the value of the system variable <Wimp$ScrapDir>. If
you get messages about not being able to create temporary files then check
that you have a !Scrap directory. In all cases it will need approx 200K
above its wimpslot to run.

DECOMPRESSED IMAGES
-------------------

Images can be decompressed to 6 different types of file from the Browser
menu.

For a 24 bit RGB JPEG file the possible choices are :-

Standard:    This is a MODE 15 or 28 sprite with the standard 256 colour
palette and can be viewed correctly in any 256 colour screen mode.

Grey:        This is a MODE 15 or 28 sprite with a palette consisting of 256
levels of grey. Although all the detail cannot be viewed on a standard
Archimedes it can be printed on a monochrome printer with more detail than a
standard palette sprite.

Optimised:   This is a MODE 15 or 28 sprite with a palette optimised to use
the most common colours in the image to give the best possible 8 bit image.
Unfortunately the only current way to view it correctly is with a 3rd party
enhanced graphics card. It may however give better printed results on a
colour printer than the standard palette sprite.

32 thousand colours: This is a new format sprite and is a useful trade off
between quality and file size.

16 million colours:  This is a new format sprite and gives the best possible
image that can be created.

Clear:       This is a 24 bit Clear file and cannot be viewed in this form.
Clear files are a common interchange format for 24 bit graphics files on the
Archimedes and most applications that can deal with 24 bit colour will be
able to load a Clear file.

For an 8 bit grey scale JPEG file the possible choices are :-

Standard:    As above
Grey:        As above

Optimised:
32 thousand colours:
16 million colours:

Selecting any of these three formats will produce the same as selecting the
256 grey option as that will give the best quality that is available.

Clear:       This is an 8 bit clear file with a 256 greyscale palette attached.

VERSIONS
--------

This application comes in two forms.

Full version    - features as described above.
Limited Edition - cannot save new format sprites or create directories.
Read Only       - cannot save Clear or new format sprite files and cannot
                  import images.

The Read Only version is freely distributable as long as the following
conditions are abided by.

1) NONE of the files within the application are removed or altered in any
   way. This includes all images, code and data files.

2) No charge is made.

The Full version is only available from:-

Irlam Instruments Ltd.
Brunel Institute for Bioengineering
Brunel University
Uxbridge
Middlesex
UB8 3PH
0895 811401

All software © Irlam Instruments Ltd. 1994-1996 except those portions provided by
the Independent JPEG Group.

Written by Simon Middleton for Irlam Instruments Ltd. Apr 1993 - Mar 1994.

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