!Jclean version 2.01


!Jclean is a desktop front end (or interface) for the
Independant JPEG Group utilities 'jpegtran' and 'wrjpgcom'.
It allows all operations available from these utilities to
be performed by clicking and drag-and-drop rather than
having to resort to the command line.

Click SELECT on the icon bar icon to open up the Jclean
action window. In previous versions of Jclean, JPEG files
were dropped on the icon bar icon. In version 2.00, JPEG
files (and text files - see below) must be dropped on a box
(icon) in the Jclean action window.

Full details of all the options are given below in this file
but you might find it easier to use an interactive help
application. where placing the pointer over an icon will
provide information pertinent to that icon.



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Why use Jclean?

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1. Because it can make many JPEGs smaller by optimizing the
encoding parameters or by stripping unwanted markers such as
text comments, embedded thumbnail images, or Photoshop
settings.

2. Because it can perform various useful transformations on
the image.

3. Because it can insert your comments into a JPEG file -
such as a copyright notice, or perhaps the date, location,
subject or other details of the photo.

4. Because it does any or all of reasons 1 - 3 without any
degradation of the image which would occur were you to
decode, change and re-encode the image e.g. by passing it
through ChangeFSI.



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SOME IMPORTANT POINTS

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The original JPEG file will be deleted and replaced by the
result file - so ensure you have a backup copy if you don't
want to lose information.

Jclean needs to write to a new output file before deleting
the input file and renaming the output to the same name as
the input. so, you must ensure that the directory containing
the file has fewer than the maximum number of files in it.
In versions of RISC OS prior to 4.00, ADFS allows only 77
files in any directory.

Errors may occur if e.g. there is not enough disc space, or
the medium is write protected. Please keep backup copies of
the JPEG files you pass through Jclean until you are certain
of an error free process.

Overlong pathnames (i.e. too deep a directory structure)
will probably cause problems. If this happens, move the
files nearer the root directory.

You are advised to read the files inside the 'doc' directory
inside !Jclean, particularly the sections on 'jpegtran' and
'wrjpgcom' in the file, 'usage'.

RISC OS ports of the other utilities by the Independant JPEG
Group (cjpeg, djpeg and rdjpgcom) are available (for command
line use) from Jrme Mathevet's website:

http://www.multimania.com/mathevet/jpegv6b.zip

The usual disclaimer: This software may be completely
unsuitable for any purpose to which you will put it so don't
blame me if it sets your house on fire. You use it at your
own risk. That said, you may use it freely and distribute it
provided no charge is made.

Bug reports: david@dacha.freeuk.com



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Jclean options

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The 'action' box ("Drag files to this box")

  (Not really an option...) Jclean will only acknowledge
  JPEG files and Text files (see the 'Add comment' option)
  which are dropped on this box.

  This is a safety measure: it is all too easy to drop files
  during a drag, so limiting the area of acceptance
  minimises the risk of changing a file in error. At the
  same time, the box is just less than eight times the area
  of the icon bar icon and so easier to hit for users with
  coordination difficulties.

  You may drop individual files or selected groups of files
  - in which case, Jclean will process them in alphabetical
  order (as sent by the Filer). Jclean will not accept
  directories and will not recurse through a directory
  structure. Again, this choice has been made for safety.


Cancel

  Close the Jclean action window.


Clean Options

  Set the options for a 'clean' JPEG. Basically, this is
  just Optimised.


Load Options

  This loads the options you've previously saved.


Save Options

  This saves all the options you've set.


Optimized

  This ensures the most efficient encoding parameters,
  usually producing a smaller file.


Progressive

  This produces a JPEG which decodes in a way similar to
  interlaced GIFs in that a full-size image of low quality
  is displayed quickly with more detail being filled in on
  each subsequent pass. It would be ideal for slow internet
  connections but for the fact that not all decoders
  recognise it - in particular, it causes RISC OS some
  problems!


Greyscale

  This removes any colour information in the image, leaving
  only luminance (i.e. a scale of black to white). You can
  use this option to convert a coloured image to monochrome
  or to remove erroneous colour channels from a grey image
  incorrectly encoded as coloured. The advantage is a
  quicker decoding time.


Transform

  This allows mirroring and 90 degree rotation of the image
  without image degradation. Such transformations can only
  be carried out on complete blocks so that anything up to
  15 pixels at an edge may not be transformed correctly.

Trim edge

  This removes edge pixels of incomplete blocks that cannot
  be transformed correctly. The information is lost and
  cannot be recovered but trimming is necessary if the
  transformed image is not to appear strange.

  The options for Transform are:
  
  Flip horizontally
  Flip vertically
  Transpose across upper left to lower right axis
  Transpose across upper right to lower left axis
  Rotate 90 degrees anticlockwise
  Rotate 180 degrees
  Rotate 90 degrees clockwise


Copy

  This copies 'markers' such as textual comments, embedded
  thumbnails and proprietary settings from the input to the
  output file.

  The options are:
  
  Copy text comments only
  Copy all markers
  Copy none (the action when 'Copy' is not selected)

  NOTE -   that if both 'Add comments' and 'Append' are
  selected, then 'Copy' will always copy comments to the
  output file even when not selected.


Add comment

  This option uses the 'wrjpgcom' utility (all the others
  use 'jpegtran') and so requires a second pass if any of
  the other options are selected.

  It allows you to insert text comments into JPEG files. The
  comment should be in a text file and Jclean must 'see' the
  text file before it 'sees' the JPEG file i.e. you must
  drop the text file on the 'action' box before dropping the
  JPEG file on it.

  Jclean will remember the path of the last text file
  dropped on it until it is quit. If you are inserting the
  same message (e.g. a copyright notice) into all JPEGs, you
  need only drop the text file on Jclean once.

  If you wish to insert different information into each JPEG
  (e.g. subject details), you might find it easiest to
  create your text files first, ensuring that each is
  alphabetically earlier than the corresponding image, then
  drag all text and JPEG files to Jclean (after setting the
  correct option).

  E.g. Image0      (Text)
       Image0/jpg  (JPEG)
       Image1      (Text)
       Image1/jpg  (JPEG)
       Image2      (Text)
       Image2/jpg  (JPEG)
       etc.

  The options for 'Add comment' are:
  
  Append - add your new comment after existing comments.
  Replace - remove existing comments, then insert yours.
  
  NOTE -   that if both 'Add comments' and 'Append' are
  selected, then you do not need to select 'Copy' as well.


Set restart markers

  This sets markers after every Nth row of blocks which
  allow decoders to resume correctly even if data on the
  previous row has become corrupt (e.g. during downloading
  on the internet) and would otherwise result in the rest of
  the image being unrecoverable. This is useful only if the
  decoder is known to recognise it. If selected, there seems
  little point in using a value of N other than 1.


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end of !Help file.
