Acorn User 13/AUCD13.iso/argonet/creator.spk/!Creator_Docs_Guide

Text File | 1993-05-31 | 18.4 KB | 491 lines

>Guide

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This program is SHAREWARE. It is *not* free software. You may evaluate it for
a two-week trial period. After this, you are required to register for further
usage, or else destroy your copy. Refer to the end of this guide for details.
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This application is based in part on the Independent JPEG Group's JFIF coding
and decoding software, version 4 (Dec 1992), used for writing the JFIF format.

_______________________________________________________________________________

Creator 1.41                                       ---------------------------
                                                    This program is SHAREWARE
Version date : 31 May 1993                         ---------------------------

----------------
- Introduction -
----------------

Creator can create several foreign graphics formats, using either Archimedes
sprite files (filetype &FF9) or !Translator's Clear files (filetype &690) as
input. For more information on !Translator, refer to the end of this guide.

Currently Creator can create the following graphics formats :

- GIF (Graphics Interchange Format) files
- TIFF (Tag Image File Format) files
- AIM (Archimedes/Amiga/Atari Image Manager) files
- PBMPlus (Portable Bit Map toolkit) files
- JPEG (Joint Photographic Experts Group) 'JFIF' files


---------------
- The formats -
---------------

The formats that Creator is currently able to create will be briefly introduced
below.

- GIF

GIF is a general file format for raster graphics data, devised by and trademark
of Compuserve Inc., which uses a variation of LZW data compression to reduce
the file's size drastically.

GIF files are common to encounter on bulletin boards. GIF readers and writers
are available on a very large variety of computer systems.

- TIFF

TIFF is a general file format for graphics (and related) data, devised by Aldus
Corporation and Microsoft Corporation. It can contain a wide variety of
graphics data, and there is support for several compression schemes to reduce
the file's sizes.

The TIFF format has been adopted by several companies and programs (and more
will follow in the future) as the way to output and exchange graphics data.

TIFF readers and writers are available on a large variety of computer systems.

- AIM

AIM is the graphics format supported by the !AIM (Archimedes Image Manager)
application. It is a simple format with no support for compression.

The !AIM application can perform reasonably powerful image processing on
greyscale images.

- PBMPlus

PBMPlus is an intermediate format for graphics used by the famous(?) Portable
Bit Map toolkit suite of C programs for Unix machines, created by Jef
Poskanzer. It is an extremely simple format, with no support for compression.

The PBM formats (pbm for bilevel, pgm for greyscale and ppm for colour images)
serve as an intermediate between a very large range of other graphic formats.
The PBMPlus package includes utilities for manipulating the PBM formats in
several ways (scaling, colour quantization, etc.).

- JPEG

JPEG is a true-colour or greyscale format that uses a 'lossy' compression
technique based on a Discrete Fourier Transform (DCT). The algorithm is
called 'lossy' because it loses colour information in the compression process,
but the loss is usually hardly noticable (if at all), while the compression
ratio is much greater than can be achieved with lossless compression methods.
The amount of loss can be influenced by specifying a 'quality' factor,
expressed as a percentage, which (theoretically) may lie between 1% (very high
compression ratio, low quality) and 100% (lowest compression ratio, highest
quality). In reality, factors between around 30 and 95 are usable (even 100%
loses colour information, while yielding very low compression ratios, 95% is a
good maximum value to use).

JPEG (or JFIF) files are not created directly by Creator : the input image is
first converted to PBMPlus by Creator, and then fed to a seperate executable
(by the Independent JPEG Group) which converts the PBMPlus file to a JPEG file.

You can also use the executables (cjpeg, the compressor, and djpeg, the
decompressor) yourself. Documentation is provided in the Docs directory.


-------------------------
- Using the application -
-------------------------

To start up Creator, double-click on the '!Creator' icon.

It will install itself on the icon bar, and clicking MENU on Creator's icon
pops up the main menu, giving the usual 'Info' and 'Quit' options, and others,
which will be discussed further on.


-----------------
- The main menu -
-----------------

This menu, popped up by clicking MENU on Creator's iconbar icon, contains a
number of icons (some of which lead to submenu's/windows). The functions of the
icons will be discussed below.

The main purpose of the main menu is to provide access to Creator's control
window (via the 'Control' icon), which contains (in groups) most of the
available options and controls.

-----------
| Control |
-----------

Gives access to Creator's control window, which contains most of Creator's
options and controls, divided into groups.

Clicking on this icon will make this window permanent (but it can be closed
again by clicking on its close icon).

One type of icon appears in the control window :

- Radio icon sets. Icons in these sets are diamond shaped, and act like the
  toggle icons, but only one of them may be on. Switching any one on will
  switch off all the others in the same set (hence the name 'radio' icons).

The functions of the icons in the control window are discussed below. Icons are
identified by giving their 'path', i.e. group name (name on the border
surrounding the group), if appropiate followed by sub-category (medium grey
heading), followed by the icon's own name, seperated by '|'s.

\\\\\\\\\\\\\\\
 Output format  ***
///////////////

This radio icon set enables selection of the output format.

\\\\\\\\\\\\\\\\\\\\\
 Output format | GIF
/////////////////////

A GIF (Graphics Interchange Format) file will be created.

NOTE : The GIF standard only supports 'paletted' images, up to 8 bits per
pixel. You therefore cannot use >8 bit (i.e. pure RGB) Clear files as input.

The created GIF file conforms to the 'GIF87a' standard.

The Translator filetype for GIF files is &695.

\\\\\\\\\\\\\\\\\\\\\\\\\\
 Output format | TIFF xxx
//////////////////////////

A TIFF (Tag Image File Format) file will be created.

The 'suffix' determines the compression scheme that should be used in the TIFF
file. When using any of the compression schemes, bear in mind that the 'target'
machine's TIFF reader must be able to handle it. Consult the TIFF reader's
manual first.

None
----
No compression. This ensures that all TIFF readers can handle the resulting
TIFF file, but relatively big files will result.

Packbits
--------
TIFF PackBits compression. This simple compression scheme works well on most
images (usually worst on digitised images, and best on 'drawings').

LZW
---
TIFF LZW compression. This is the most powerful (and complex) compression
scheme, and will usually yield the highest compression ratio. It works well on
almost any kind of image. When your target TIFF reader can handle LZW
compression, obviously this is the preferred setting.

NOTE : The TIFF files created conform to Revision 5.0 of the TIFF standard. For
'paletted' input (<=8 bits per pixel), only 1, 2, 4 and 8 bits per pixel files
are accepted.

The exact TIFF subformat produced is as follows :

For >8 bit per pixel files (which currently only Clear can carry), TIFF Class R
images (24-bit RGB colour) is produced.

For 8, 4 and 2 bit per pixel files (either sprite or Clear can carry these),
TIFF Class P (Palette colour) is produced.

For 1 bit per pixel (again from either sprite or Clear), either TIFF Class P
(Palette colour) is produced, or TIFF Class B (Bilevel, i.e. no palette, always
one colour black and the other white). Class P is produced if the 'TIFF
Bilevel' flag is OFF. Class B is produced if the 'TIFF Bilevel' flag is ON,
*regardless* of the actual colours in the image (the Class B variant with white
(colour 0) on black (colour 1) is chosen if colour 0 in the image is lighter
than colour 1, and Class B with black (colour 0) on white (colour 1) is chosen
if colour 1 is the lighter colour. Obviously, with this scheme, black & white
input always comes out right anyway, and others are converted to the closest
sensible variant.

The Acorn reserved filetype for TIFF files is &FF0.

\\\\\\\\\\\\\\\\\\\\\
 Output format | AIM
/////////////////////

An AIM (Archimedes Image Manager) format file will be created, including a
header file '<file>+'.

This format contains 8 bits per pixel (greyvalues from 0 (black) to 255
(white)). The main file size is always X*Y bytes, the header file contains
further information (format, resolution, etc.).

NOTE : As AIM processes raw greyscale data, not 'pretty pictures', avoid using
dithering in the input image (i.e. when scaling or converting to grey with
Translator) as this messes up the true greyvalues of the pixels and may hinder
correct processing by AIM.

Creator transforms colours in the input image to greyvalues by using greyvalue
weights 0.300, 0.586 and 0.114 for red, green and blue respectively. Thus, the
greyvalue of a colour becomes R*0.300+G*0.586+B*0.114.

The filetype for AIM files is &004, the header file has filetype &010.

Always copy the header file along with the image file. When the image's
resolution is is 256x256 pixels, this is not strictly necessary, as AIM assumes
images without a header file to be 256x256 pixels.

\\\\\\\\\\\\\\\\\\\\\\\\\
 Output format | PBM xxx
/////////////////////////

A PBMPlus (Portable Bit Map) format file will be created.

The 'suffix' determines what kind of pixel value format is used in the PBMPlus
file.

Decimal
-------
This creates the decimal-value (or ASCII) versions of the pbm, pgm and ppm
formats. Every pixel is stored as a decimal value (in ASCII), seperated by
spaces and newlines, and thus resulting files waste a lot of space.

Packed
------
This creates the packed (or binary) versions of the pbm, pgm and ppm formats.
Pixels are packed in bytes 8 at a time for pbm, 1 byte per pixel for pgm and 3
bytes per pixel (red, green and blue components) for ppm. These formats are
processed easier and faster by the PBMPlus package and are quite a bit more
compact than their decimal equivalents.

The format actually created is automatically determined as follows :

- The pbm formats P1 (decimal) or P4 (packed) are created for black & white, 1
  bit per pixel input. Thus, the palette must have one colour black, and one
  white (white being a bit more flexible : a range of 240-255 (&F0-&FF) is
  accepted for the (identical) red, green and blue components of the grey
  shade).
- The pgm formats P2 (decimal) or P5 (packed) are created for grey-scale input
  that does not fit pbm. 1-8 bits per pixel are accepted, and the palette must
  consist entirely of grey shades.
- The ppm formats P3 (decimal) or P6 (packed) are created for all other input,
  i.e. >8 bits per pixel or non-pbm/pgm colour input.

The Translator filetype for PBMPlus files is &69E.

\\\\\\\\\\\\\\\\\\\\\\
 Output format | JPEG
//////////////////////

A JPEG (Joint Photographic Experts Group) 'JFIF' format file will be created.

The quality factor may be specified in the icon behind the JPEG switch (1-100).

\\\\\\\\\\\\\\\\\\\\\\\\
 Options | TIFF Bilevel  ***
////////////////////////

See 'Output format | TIFF'. In short, for 1-bit per pixel input, a TIFF Class B
image is output if this flag is set flag is set. If it is not set, a TIFF Class
P image is written out.

----------
| Status |
----------

This icon gives access to a submenu of status handling functions.

Creator's status consists of the items marked with ***.

- Save

Clicking on this icon will save the current status in Creator's status file.

This file (when present) is always loaded on startup, or may be explicitly
loaded by using the 'Load' option (to override the current status).

- Load

Clicking on this icon explicitly (re-)loads the status file, overriding the
current status.

- Default

Clicking on this icon selects the default status settings.

- Kill

Clicking on this icon will remove the status file. 'Standard' defaults will
be used when Creator is next started up.


-------------------
- Creating a file -
-------------------

To create a file of the selected graphics format, simply drag your input file
to the iconbar icon.

A 'Save as' window will pop up, in which the leaf filename for the resulting
file may be entered (by default it is the leafname of the input file). The
filetype icon should then be dragged to a filer window, as usual.

The hourglass is displayed during processing. The percentage displayed in the
hourglass indicates how much of the input file has been processed. The top and
bottom 'LED's of the hourglass are 'on' when image data is being loaded/saved
respectively.


----------------
- Memory usage -
----------------

Creator always runs in a minimum amount of memory.

When an image is to be created, Creator grabs all available memory for (among
others) in- and output file buffers, and releases it immediately after
processing.

In general, larger in- and output file buffers speed up processing. It is
therefore recommended to ensure that a reasonable amount of free memory is
available.


----------------
- Sprite input -
----------------

Only the first sprite encountered in a sprite file will be included in the
output file. One reason for this is that, although GIF and TIFF files may
contain more than one image, the standards do not require readers to do
anything with images beyond the first one encountered.

There's an interpretation problem concerning a sprite's palette. Because Acorn
decided to register the R, G and B components of colours as 8-bit values, but
only uses the top 4 bits (because VIDC's DACs are only 4 bits), strictly
speaking there is no way of telling if the R, G and B values are to be
interpreted as 4-bit or 8-bit. For 4-bit values, the higher nibbles should be
copied to the lower nibbles to get the correct 8-bit value, as a value of, say,
15 for each of R, G and B actually means 'full white' (i.e. &FF), and not &F0,
as it is recorded.

Because there *may* be non-standard sprites around that already do use the
lower nibble (i.e. full 8-bit values), or already had the higher nibbles
copied to the lower, Creator first checks if all lower nibbles are zero, and,
only if so, copies the higher nibbles to the lower.


---------------
- Clear input -
---------------

It is strongly recommended that you use Clear files as input for Creator when
converting from one graphics format to another, as the Clear format always
preserves the exact colour content of the original image.


-------------------------
- Translator & GreyEdit -
-------------------------

These applications, which were also written by me, are essential companions to
Creator.

Translator reads a very large number of (mainly foreign) graphics formats, and
can perform colour processing, dithering, scaling, rotate, etc.. It outputs
either sprite or Clear files. All graphic formats accepted by Translator may be
converted by Creator to GIF, TIFF, etc. by using the Clear format as an
intermediate.

GreyEdit can process and edit 256-level greyscale (digitized) images. In
addition it can grab video images from the Zeridajh Video Digitiser podule,
when this is present. Several extremely fast filter algorithms, histogram
equalization, range expansion and inversion may be applied to whole images. In
addition, noise pixels may be edited by hand, and sides of images may be cut
off, optionally aided by zoom functions for precise editing.

Translator and GreyEdit are available from the address mentioned below and are
part of my shareware image processing package.


-----------
- The end -
-----------

This application is Shareware, and part of the image processing package
consisting of !Translator, !Creator and !GreyEdit.

I have put a lot of effort and time into these programs. Therefore, if you find
any of them useful, I kindly ask you to register yourself as a user of these
programs. The registration fee is just 35 dutch guilders. You will receive a
free disc with the latest versions of Translator, Creator, GreyEdit, and most
of my other applications.

You may not use or have this software in your posession beyond a two-week trial
period without registering.

Services that offer software for download (BBSses, mail servers, ftp sites,
etc.), and PD/Shareware libraries and the like, may *not* store this software
without my approval.

If you want to register, or if you have praise, complaints, comments, bugs(!),
or anything else to offer me, do not hesitate to write to

John Kortink
Nutterbrink 31
7544 WJ Enschede
The Netherlands

or try email to [e-mail].

Payment NOTE
------------
Payment in CASH ONLY PLEASE, in any currency, for the equivalent of 35 dutch
guilders (England £10). The only exceptions may be (in order of preference) :

a) A Eurocheque, for 35 dutch guilders, *with* pass-number on the back
b) Postal exchange for 35 dutch guilders
c) Any other form of payment, which gets charged by the bank, but which I'm
   happy to accept if I end up with 35 dutch guilders after bank charges.
   Typical bank charges are £8 on any non-a) payment.

Updates NOTE
------------
If you want Translator or Creator to handle a new format, always send me full
information, and several example files.

For registered users, new versions of the applications are available from the
same address : just send £1 to cover postage and a self-addressed envelope
containing a formatted 3.5" disc. You will receive the latest versions. Discs
will always be returned immediately, and will not be put 'on hold' awaiting
new versions.

NOTE : I will *not* send new versions to unregistered users. Ask yourself if
you wouldn't be better off registering, if only to get new versions easily.

Happy imaging !!!

_______________________________________________________________________________

!!! NOTE !!!

You may NOT change this application or use ANY part of it in other products
without my approval. You may spread it freely (with *ALL* files included), but
not for any profit. This software is provided 'as is'. Using it is entirely at
your own risk.

This application may NOT be distributed as an 'extra' in commercial products.
You are kindly invited to contact me to discuss financial details, should you
want to do so.

_______________________________________________________________________________