!Jcut version 3.01 (Sun 06th October 2002)

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  #  Please read Help Section 10 SOME IMPORTANT POINTS  #
  #  at the end of this file before using !Jcut.        #
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!Jcut supports interactive help. You may find it best to use
this until you are familiar with all the buttons.

!Jcut can be used merely as a fairly quick JPEG viewer, and
multiple copies can be run for image comparison.

!Jcut performs a limited set of operations on JPEGs without
having to decompress and recompress them. This avoids image
degradation. No guarantee is given that !Jcut will work
correctly, or at all, on every type of JPEG. It has worked
correctly on all JPEGs tested on it so far, including
paste/join builds from Mavica JPEGs up to over 3000 pixels
in both dimensions.

Help sections...

  1. JPEG BLOCKS, EXIFS & THE 'BANDING' PROBLEM
  2. THE ICON BAR ICON
  3. DISPLAY OPTIONS IN THE JCUT ACTION WINDOW (JAW)
  4. THE GRID - COLOUR, SIZE, SELECTION, SECTIONS & CHOPPING
  5. FULL IMAGE - CONTRAST AND COLOUR ADJUSTMENT
  6. FULL IMAGE - GREYSCALE, CROPPING, DELETING, TRIMMING
  7. FULL IMAGE - ROTATING, FLIPPING, TRANSPOSING
  8. SAVING - FULL JPEG, SELECTION, SECTIONS, OPTIONS
  9. PASTE MODE - PASTING AND JOINING
 10. SOME IMPORTANT POINTS




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1. JPEG BLOCKS, EXIFS & THE 'BANDING' PROBLEM

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All cut and paste operations done by !Jcut are limited to
the JPEG block boundaries (sample size) in which the JPEG
was compressed.

Common block sizes are...

16 by 16 pixels

  A common block size for coloured JPEGs, including those
  produced by ChangeFSI.

8 by 8 pixels

  Greyscale JPEGs, including those produced by ChangeFSI.
  Unfortunately, 8x8 block images cannot be pasted or joined
  to 16x16 block images.
  
  Photoshop coloured JPEGs may have 8x8 pixel blocks.

16 by 8 pixels

  JPEGs created by Sony Mavica digital cameras use this block
  size. It is problematic because rotated images cannot be
  pasted into non-rotated images. Nor can 16x16 block images
  be pasted into them.
  
  The Exif files created by other digital cameras contain
  JPEGs with 16x8 pixel blocks.

other sizes...

  It is possible to create JPEGs with a block size of 32 by 16
  pixels. Although the code in !Jcut itself can handle them,
  the JPEG SWI in SpriteExtend used to display the JPEG cannot
  (neither can !ChangeFSI, although !ImageMaster and !Fresco
  seem able to).

incomplete blocks...

  If the image is not an exact multiple of the block size,
  then the right hand edge and/or the bottom edge will have
  'incomplete edge blocks'. These incomplete blocks cannot be
  on the left side or the top, so if the image has incomplete
  blocks, some of the transformations available in !Jcut will
  not work on the complete image.


Exif warning...

  'Exif' files (usually digital camera images), which contain
  the main image JPEG, a thumbnail JPEG and various bits of
  information, will be converted by 'jpegtran' into JFIF
  JPEGs. None of the information will be lost unless you
  select the "Strip comments" option on saving but any
  applications which expect 'Exif' files may not be able to
  see the information in the resulting JPEG. You should keep a
  backup copy before doing any processing.


Banding problem...

  The JPEG SWI in SpriteExtend displays most rotated digital
  camera JPEGs (i.e. 8x16 pixels per block) incorrectly,
  producing banding. To the best of my knowledge, this is not
  a fault in the JPEG file. Other applications which use
  SpriteExtend to display the JPEGs (e.g. !Thump and !Draw)
  also show the banding but those applications which use their
  own code to decompress the JPEG (e.g. !Fresco, !ImgMaster
  and !ChangeFSI) display them correctly.




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2. THE ICON BAR ICON

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Menu...

  Info    : the usual "About this program".

  Help    : runs this file.

  Jcut... : opens the !Jcut Action Window (JAW) and also
            the image window if a JPEG is loaded.

  Clear   : removes any loaded JPEG from memory.

  Quit    : ends !Jcut (see 'Quitting !Jcut' below)



Select...

  Clicking SELECT over the icon bar icon opens the JAW and/or
  image window, depending on whether a JPEG is loaded and on
  what windows were last open. This 'intelligent' opening
  ensures that the JAW needn't be opened when using !Jcut just
  for viewing JPEGs. If a JPEG is loaded, clicking SELECT a
  second time will ensure that both windows open.


Adjust...

  Clicking ADJUST over the icon bar icon closes all open
  windows.


Drag and drop...

  Drop a JPEG on the icon bar icon. If the file is not too
  large, and if it is not corrupt in any way, an image window
  will open. You can drop subsequent JPEGs directly into the
  image window. You can also load JPEGs by dropping the icon
  into the filepath box at the top left of the JAW, or just by
  double-clicking over a JPEG icon in a Filer window. If !Jcut
  is not running but has been seen by the Filer, it will be
  started by double-clicking over a JPEG file icon. (Other
  applications may interfere with this feature.)


Quitting !Jcut...

  When !Jcut quits, it saves the state of the options selected
  in the JAW. When you next run it, these options will be read
  and set as you left them.




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3. DISPLAY OPTIONS IN THE JCUT ACTION WINDOW (JAW)

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A. The top left area of the JAW has options for display and
for loading and saving the JPEG.

The top icon is a box showing part of the load-path (the
file address of the last JPEG dropped into !Jcut). You can
drag and drop a JPEG icon to this box and !Jcut will load
the JPEG.

The 6 button icons on the next (2nd) row are:

1. Save back (JPEG behind blue disc)...

  This saves the currently loaded JPEG back to the address
  shown in the load-path. None of the save options (in the
  right hand side of the JAW) are used. This is useful when
  making simple changes to JPEGs - e.g. rotating a digital
  photograph. The file date of the JPEG is unchanged when
  saved back using this button. (see part B at the bottom of
  this help section) ADJUST has the same action as SELECT.

2. Close (crossed out JPEG)...

  Clicking SELECT closes the JPEG image display window if it
  is open. Clicking ADJUST closes both the image window and
  the JAW. (Click SELECT on the icon bar icon to open them
  again.)

3. Open (JPEG)...

  This opens the JPEG image display window if a JPEG is
  currently loaded. If the image window is already open, this
  will bring it to the front. ADJUST has the same action as
  SELECT.

4. Help ('i' on blue background)...

  This is the same as the 'Help' option offered in the icon
  bar menu. It loads this file. ADJUST has the same action as
  SELECT.

5. Clear (bin)...

  This is the same as the 'Clear' option offered in the icon
  bar menu. Any loaded JPEG is removed from memory. It does
  not delete the JPEG from disc. ADJUST has the same action as
  SELECT.

6. Reload (JPEG in front of blue disc)...

  This attempts to reload the JPEG addressed by the load-path
  shown in the box just above the button. This will not be
  possible if the file has been deleted or if the JPEG was
  saved into !Jcut from another application (or, indeed, from
  !Jcut itself). If !Jcut is in Paste Mode, a reload will
  abort the paste operation. You will be given the opportunity
  to cancel the reload. ADJUST has the same action as SELECT.


The 2 buttons on the next row control zoom and dither:

1. Zoom (magnifying glass)...

  !Jcut allows half size (50%), normal size (100%) and double
  size (200%). The current zoom setting is shown in the box to
  the right of the button and can be set when no image is
  loaded. If an image is loaded, it takes immediate effect.
  SELECT cycles the zoom setting 50 > 100 > 200 > 50 and
  ADJUST cycles 200 > 100 > 50 > 200. From any of the three
  settings, either of the other two can be obtained by a
  single click.


2. Dither (dots)...

  Dither (error diffusion) is limited to that allowed by the
  SpriteExtend JPEG rendering module and has three settings
  which take immediate effect if an image is loaded. The
  dither can be set before loading an image. 'None' is the
  quickest to render but not recommended for less than 16
  million colour modes. 'Quick' uses either of two optimised
  methods, depending on the screen mode, which may not work
  correctly if the JPEG block size is not 16 by 16 pixels.
  'Full' error diffusion (for 256 colour modes) is the most
  accurate but far slower to render. SELECT cycles the dither
  setting 'None' > 'Quick' > 'Full' > 'None' and ADJUST cycles
  'Full' > 'Quick' > 'None' > 'Full'. From any of the three
  settings, either of the other two can be obtained by a
  single click.


B. The bottom left area of the JAW displays the time and
date of the JPEG file. It is placed here so that it is
against the 'Stamp' option in the 'Save' section of the JAW.
(see Help Section 8) The file date display is useful if
it is the date on which a digital photograph was taken.




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4. THE GRID - COLOUR, SIZE, SELECTION, SECTIONS & CHOPPING

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The left upper centre of the JAW shows the !Jcut grid and
has buttons for preset divisions.

The JAW grid represents the actual grid drawn on the JPEG
image when both it and the JAW are open.

With some images, the right hand and/or bottom image grid
lines may be drawn beyond the edges of the actual image.
This occurs when the width and/or height of the image is not
an exact multiple of the block size. (see Help Section 1)
The image grid lines keep to the full block positions as a
visual indication that the edges are incomplete blocks. The
figures above and to the left of the corresponding JAW grid
sections do give the actual pixel sizes.


Grid line colour...

  The top left button allows you to select the colour used for
  displaying the grid lines on the image window. Any of the 16
  Desktop Palette colours may be used and this colour is
  exclusive-OR'd with the underlying image colour. This is the
  quickest method of drawing these movable lines but the
  actual colour of the grid lines on the image varies with the
  image colour and the screen mode. Clicking SELECT on the
  button cycles through the 16 colours to let you find the
  best for any particular image. ADJUST cycles in the reverse
  direction. A Desktop colour with all zero bits (usually
  black) will produce 'invisible' grid lines.

Image size...

  The box next to the grid colour button shows the full size
  in pixels (width by height) of the currently loaded JPEG. If
  you delete part of the JPEG (see Help Section 6), the
  figures will change to reflect the new size.

  The !Jcut grid lying under the size box represents the
  position of the grid lines in the JPEG image window. The
  figures along the top and down the left hand side provide
  the pixel width and height of all 9 possible sections.


The following explanation may be more easily followed with a
sample JPEG loaded into !Jcut.

Selection...

  On loading a new JPEG, the image grid lines are set to the
  edge and the central part of the JAW grid becomes very dark
  grey. This very dark section is the selected section or
  'selection'.

  By dragging with SELECT over the JPEG image window, the
  gridlines form a box over the dragged area. This box
  corresponds to the 'selection' in the JAW grid. If the lines
  are not quite in the right place, you can adjust their
  position by dragging them using the ADJUST button. The lines
  will seem 'jerky' in their movement since they can only be
  set to the boundaries of the JPEG block sizes (usually 16 by
  16 pixels). You can select any area of the JPEG in this way
  to save out as a new JPEG. (see Help Section 8)

Sections...

  Now that the image grid lines have moved from the edge, some
  or all of the other sections in the JAW grid will have
  turned dark grey. The figures along the top and left edges
  show the sizes of these sections. You can click in any of
  the dark grey sections of the JAW grid to make it the
  'selection' for saving - or you can save out in one go all
  the sections as separate JPEGs. (see Help Section 6)

Chopping...

  6 of the 7 buttons below the JAW grid automatically section
  off the image into 1, 2, 3, 4, 6 or 9 nearly equal sections.
  Where the grid pattern shown on the button is not the same
  vertically as horizontally, clicking the button with ADJUST
  will swap the vertical and horizontal divisions.

  These sections will be represented in dark grey on the JAW
  grid. You can adjust the sections by dragging the lines on
  the JPEG image window using ADJUST. A major use of
  sectioning the image in this way is to save out all the
  sections as separate JPEGs (chopping it) for use on a web
  site. (see Help Section 8) You can also use it to delete
  parts of the image (see Help Section 6) or for pasting part
  of the image back onto itself (see Help Section 9).

  The 7th (rightmost) button sets the grid lines to section
  off any incomplete edge blocks. You can use this to see
  which part of an image may not transform correctly, or to
  trim off the edge.




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5. FULL IMAGE - CONTRAST AND COLOUR ADJUSTMENT

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The left lower centre of the JAW has buttons to adjust the
contrast and/or colour intensity of the JPEG; convert it to
a monochrome grey; crop or delete parts of it; or rotate,
flip or transpose it.

This help section deals with contrast and colour adjustment.
These are recoverable operations.

It is possible to adjust contrast and colour in JPEGs
without changing the data - and so without incurring the
image degradation that results from decompressing and
recompressing the JPEG. It is done by substituting standard
quantization tables other than those used for the original
compression. In general, if the original table is changed to
one normally used for a higher Q setting, the contrast or
colour intensity is reduced. If a table normally used for a
lower Q setting is substituted, the contrast or colour is
increased.

Table Q values:

  When a JPEG is first loaded into !Jcut, the Q values of the
  luminance (contrast) and chrominance (colour intensity)
  tables are determined and displayed in the boxes next to the
  contrast button (half moon) and colour button (RGB cube).


What you may see in the contrast and colour boxes:

Values 1 to 100...

  This is the Q value of the table as found by !Jcut. It might
  not be that originally used for creating the JPEG but !Jcut
  will be able to adjust it.

A dash (-)...

  If the JPEG is monochrome greyscale, it does not have colour
  information and a dash (-) is shown in the colour box.
  Colour cannot be changed in this case.

  A dash (-) will also appear in the colour box if the JPEG
  has separate tables for the three colour components. !Jcut
  can only determine the Q value and adjust colour for single
  tables and so colour cannot be changed in this case.

  If a dash (-) appears in the contrast box, the JPEG has very
  unusual tables which !Jcut cannot determine or adjust.

  Standard quantization tables have 64 single byte values but
  when JPEGs are created with Q<24, double byte values are
  sometimes (but not always) used. !Jcut will load these JPEGs
  but will display a dash (-) to show that you can't adjust
  the contrast and colour settings. (Subsequent versions of
  !Jcut may be able to adjust the tables of this type of
  JPEG.)

An 'X'...

  This is used by !Jcut to indicate that the values in the
  table are zero (0) resulting in no contrast (displaying all
  middle grey) or no colour (displaying as a greyscale image).
  It is the next step after Q=100.

A dark grey background...

  If the JPEG tables are of the usual format but contain
  non-standard values, !Jcut finds the nearest standard tables
  which approximate the JPEG's tables. The Q value is given as
  normal in the contrast and colour boxes but in this case,
  the background is changed from light grey to dark grey.

  Any adjustment away from the original setting of contrast or
  colour replaces the original table by standard table values.
  If the adjustment returns to the original Q value, the
  original non-standard table values are replaced.


Adjusting contrast and colour by the 2 buttons:

Contrast (half-moon)...

  Click or hold down SELECT on the contrast button to increase
  contrast. Click or hold down ADJUST on the contrast button
  to decrease contrast. If you also hold down the Shift key
  while doing this, the values change by +/- 10.

  The contrast box now shows the original Q value, a forward
  slash (/), then the new Q value (e.g. [ 75/71 ]). Remember
  that increasing the contrast uses a LOWER Q VALUE and
  decreasing it uses a HIGHER Q VALUE.

  If you adjust the contrast back to the original setting,
  only the original Q value will be shown.

Colour (RGB cube)...

  Click or hold down SELECT on the colour button to increase
  colour intensity. Click or hold down ADJUST on the colour
  button to decrease colour intensity. If you also hold down
  the Shift key while doing this, the values change by +/- 10.

  The colour box now shows the original Q value, a forward
  slash (/), then the new Q value (e.g. [ 75/71 ]). Remember
  that increasing the colour intensity uses a LOWER Q VALUE
  and decreasing it uses a HIGHER Q VALUE.

  If you adjust the colour back to the original setting, only
  the original Q value will be shown.


Lossless greyscale conversion:

  By decreasing the colour intensity to zero (Q=100+1, shown
  in the colour box by an 'X'), the JPEG is displayed as a
  greyscale image but the colour information is not entirely
  lost. It can be retrieved by re-processing the JPEG in !Jcut
  and increasing colour to a suitable level.


Suitability:

  JPEGs created with a high Q setting (more than about 85-90)
  and those with tables containing non-standard values are not
  very forgiving of table adjustment. Substituting tables of
  more than 1 or 2 difference in Q will probably show a
  noticeable reduction in image quality. JPEGs created with a
  medial Q value (e.g. about 75) using standard tables can
  usually be adjusted across a very wide range.


Possible problems:

  Adjusted table values may cause overflow in the decoded
  values. How the image is displayed will depend on how the
  decoding software handles this. !Fresco 1.73a will display
  some blacks and dark greys with greatly increased contrast
  as white. !ChangeFSI and the SpriteExtend JPEG renderer keep
  them black.


Loss of original settings:

  The JPEG format does not provide a secure way of storing
  information about the original Q settings. This information
  is lost in the saved JPEG (but not from the JPEG still held
  in !Jcut's memory). The best you can hope for when
  re=processing a JPEG is to adjust the contrast and colour
  until it 'looks right'.




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6. FULL IMAGE - GREYSCALE, CROPPING, DELETING, TRIMMING

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The left lower centre of the JAW has buttons to adjust the
contrast and/or colour intensity of the JPEG; convert it to
a monochrome grey; crop or delete parts of it; or rotate,
flip or transpose it.

This help section deals with conversion to greyscale JPEGs,
cropping edges or deleting parts of the JPEG. These are all
non-recoverable operations and if you make a mistake, you
will need to reload the JPEG.


Greyscale (shaded black to white)...

  Clicking on this button converts a coloured JPEG to a true
  monochrome greyscale JPEG. This uses the Independent JPEG
  Group utility 'jpegtran' to remove all colour information
  from the JPEG. The block size of the JPEG is also set to 8
  by 8 pixels. Although the file size of the converted JPEG is
  less than a coloured JPEG, the lost colour information
  cannot be restored. ADJUST has the same action as SELECT.

  Coloured JPEGs can have their colour tables adjusted so that
  they display as greyscale images without the colour
  information being entirely lost. (see Help Section 5)


Crop (grid with all outer sections in light blue)...

  'Cropping' is the term used to describe trimming off
  unwanted borders or edges of a picture, to give the size or
  balance required. Adjust the grid on the JPEG image so that
  the central part covers just the area you wish to keep. (see
  Help Section 4) Clicking on the crop button will remove
  everything outside this section. ADJUST has the same action
  as SELECT.


Delete

1. (grid with light blue horizontal central band)...

  This lets you delete any number of rows (of blocks) from the
  JPEG by setting the grid so that the central row of grid
  sections covers the area you wish to remove (see Help
  Section 4) and then clicking the delete button. ADJUST has
  the same action as SELECT.

2. (grid with light blue vertical central band)...

  This lets you delete any number of columns (of blocks) from
  the JPEG by setting the grid so that the central column of
  grid sections covers the area you wish to remove (see Help
  Section 4) and then clicking the delete button. ADJUST has
  the same action as SELECT.


Trim

'Trimming' refers to the removal of incomplete edge blocks
(see Help Section 1) which may not transform correctly (see
Help Section 7). The position of the grid lines are ignored
in this case; just click on the appropriate button:

1. (grid with light blue bottom edge)...

  This trims off any incomplete blocks along the bottom edge
  only. ADJUST has the same action as SELECT.

2. (grid with light blue right edge)...

  This trims off any incomplete blocks along the right-hand
  edge only. ADJUST has the same action as SELECT.

3. (grid with light blue bottom & right edges)...

  This trims off any incomplete blocks along both the bottom
  and right-hand edges. ADJUST has the same action as SELECT.


Remember that !Jcut has no 'Undo' facility as such. If you
delete something in error, you will have to reload the
original image. (see Help Section 3)




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7. FULL IMAGE - ROTATING, FLIPPING, TRANSPOSING

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The left lower centre of the JAW has buttons to adjust the
contrast and/or colour intensity of the JPEG; convert it to
a monochrome grey; crop or delete parts of it; or rotate,
flip or transpose it.

This help section deals with rotating, flipping and
transposing the full image. These are recoverable
operations.

Rotate

1. (arrow 90 degrees anticlockwise)...

  This uses the Independent JPEG Group utility 'jpegtran' to
  rotate the whole image anticlockwise by 90 degrees. If the
  JPEG has any incomplete blocks on the right-hand edge, they
  cannot be rotated to the top edge and cannot remain on the
  right-hand side, so 'jpegtran' moves them to the bottom
  edge. See Help Section 6 on how to trim the edge. ADJUST
  rotates in the opposite direction (see Rotate 3)

2. (arrow 180 degrees)...

  This uses the Independent JPEG Group utility 'jpegtran' to
  rotate the whole image by 180 degrees. If the JPEG has any
  incomplete blocks on the bottom and right-hand edges, they
  cannot be rotated to the top and left-hand edges and so
  'jpegtran' leaves them unmoved. See Help Section 6 on how to
  trim the edges. ADJUST has the same action as SELECT.

3. (arrow 90 degrees clockwise)...

  This uses the Independent JPEG Group utility 'jpegtran' to
  rotate the whole image clockwise by 90 degrees. If the JPEG
  has any incomplete blocks on the bottom edge, they cannot be
  rotated to the left-hand edge and cannot remain on the
  bottom, so 'jpegtran' moves them to the right-hand edge. See
  Help Section 6 on how to trim the edge. ADJUST rotates in
  the opposite direction (see Rotate 1)


Flip

1. (double arrow, left to right)...

  This uses the Independent JPEG Group utility 'jpegtran' to
  mirror the image about the vertical axis. If the JPEG has
  any incomplete blocks on the right-hand edge, they cannot be
  flipped to the left-hand edge and so 'jpegtran' leaves them
  unmoved. See Help Section 6 on how to trim the edges. ADJUST
  has the same action as SELECT.

2. (double arrow, up to down)...

  This uses the Independent JPEG Group utility 'jpegtran' to
  mirror the image about the horizontal axis. If the JPEG has
  any incomplete blocks on the bottom edge, they cannot be
  flipped to the top edge and so 'jpegtran' leaves them
  unmoved. See Help Section 6 on how to trim the edges. ADJUST
  has the same action as SELECT.


Transpose

1. (double arrow, bottom-left to top-right)...

  This uses the Independent JPEG Group utility 'jpegtran' to
  mirror the image about the diagonal axis running from
  top-left to bottom-right. If the JPEG has any incomplete
  blocks on the bottom and right-hand edges, they will be
  cross-transposed to the right-hand and bottom edges and do
  not require trimming. ADJUST has the same action as SELECT.

2. (double arrow, bottom-right to top-left)...

  This uses the Independent JPEG Group utility 'jpegtran' to
  mirror the image about the diagonal axis running from
  top-right to bottom-left. If the JPEG has any incomplete
  blocks on the bottom and right-hand edges, they cannot be
  cross-transposed to the left-hand and top edges and so
  'jpegtran' leaves them unmoved. See Help Section 6 on how to
  trim the edges. ADJUST has the same action as SELECT.




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8. SAVING - FULL JPEG, SELECTION, SECTIONS, OPTIONS

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When !Jcut starts up, the JAW is not open to its fullest
extent. If you click over the TOGGLE SIZE icon at the
extreme top right of the window to open the JAW fully, you
will see that the entire right half of the JAW is a normal
RISC OS save box with many options.

Types of Saving:

The 'Save' button and save-path...

  When a JPEG is loaded (see Help Section 2), its address is
  copied into the save-path writable icon, approximately 1/3
  the way down the JAW save area. You can change the file name
  or address in the icon by clicking in it, then typing. Click
  on the 'Save' button at the bottom of the JAW save area to
  save the JPEG (or JPEGs) to the adddress in the save-path
  box.

File extension (/jpg)...

  The button marked '/jpg' just above the save-path box can be
  used to add or remove the PC-style file extension. Click
  SELECT to add the extension. Click ADJUST to remove any
  extensions.

Reload (JPEG in front of blue disc)...

  The Reload button just below the save-path box can be used
  to reload a JPEG you have just saved - or, if you type an
  address into the save-path box, it can be used to load a new
  JPEG. 

Drag and Drop...

  Alternatively, you can drag the JPEG icon to a Filer window
  or to an application which will load JPEGs. You can even
  drag the JPEG icon back into the grid part of the JAW if you
  wish to paste the current loaded JPEG into itself. (see Help
  Section 9)

  One of the options offered by !Jcut is to chop up the JPEG
  and save all the sections in one go. In this case, the JPEG
  icon is replaced by a Directory folder icon. You can drag
  this to a Filer window but not to an application with any
  expectation of it being loaded.


The options in the JAW save area fall into 3 types:

A. Save Options (3)

At the top of the JAW save area are three radio-icon options
used to determine which type of save !Jcut performs:

full JPEG...

  Select this option if you want to save the complete JPEG,
  regardless of the grid settings.

selection...

  Select this option if you want to save out only the selected
  part of the JPEG as shown in the JAW grid. Of course, if the
  grid lines are set to the edges, this will be the full JPEG.
  (see Help Section 4)

n sections...

  The option states how many sections will be saved.

  If you select this option, the JPEG icon, top right, will
  change to a Directory folder icon. When you save with this
  option, !Jcut will create a directory of the name shown in
  the save-path and will then save all the sections of the
  JPEG represented in dark grey in the JAW grid (see Help
  Section 4) as separate JPEGs named 0, 1, 2, etc., inside the
  directory. Each of these numbered JPEGs will have the same
  PC-style file extension as you give to the Directory name in
  the save-path box.


B. JPEG ('jpegtran') Options (5)

Below the save-path box are 5 tick-icon options used to
determine what actions are performed by the Independent JPEG
Group utility 'jpegtran' during the save process. The
selected operations will be carried out on all saved
sections. (The currently loaded JPEG kept in !Jcut's memory
will not be affected.):

Greyscale...

  With this option ticked, 'jpegtran' will convert a coloured
  JPEG to a monochrome greyscale JPEG during the save process.
  All colour information will be lost. (see Help Section 6)

Optimised...

  With this option ticked, 'jpegtran' will optimize the
  entropy encoding parameters during the save process. This
  results in a slightly smaller file size.

Progressive...

  With this option ticked, 'jpegtran' will convert the JPEG to
  a 'progressive' type during the save process. In this type
  of JPEG file, the data is stored in multiple scans of
  increasing quality, so that the decoder can use the first
  scan to display a low-quality image very quickly, and can
  then improve the display with each subsequent scan. This may
  be useful over slow internet connections but not all JPEG
  viewers may be able to decode progressive JPEGs.

Strip comments...

  With this option ticked, 'jpegtran' will remove all embedded
  comments during the save process, including all text
  comments and thumbnails. Do not tick this option if the JPEG
  is a digital camera image containing vital information.

Transformed...

  With this option ticked, 'jpegtran' will transform the JPEG
  during the save process. Below this option are 7 radio-icon
  options allowing you to choose which transformation is
  carried out:

    1. rotate 90 degrees anticlockwise
    2. rotate 180 degrees
    3. rotate 90 degrees clockwise
    4. flip left-right
    5. flip up-down
    6. transpose bottom-left to top-right
    6. transpose bottom-right to top-left

  See Help Section 7 for a description of these
  transformations and the problems with incomplete edge
  blocks.


C. File Options (3)

Below the transformation options are 3 tick-icon options
dealing with files:

Warn on overwrite...

  With this option ticked, !Jcut will issue a warning if a
  file is going to be overwritten, giving you the chance to
  abort the save. Even with it not ticked, !Jcut will not
  overwrite files that are locked or marked as 'read-only'.

Lock...

  With this option ticked, !Jcut will lock the saved file. If
  it is not ticked, the saved file will be unlocked.

Stamp...

  When this option is ticked, !Jcut will stamp the saved file
  with the current time and date. If it is not ticked, !Jcut
  will use the time and date of the loaded JPEG file (shown in
  the date box to the left of the 'Stamp' option) for the
  saved file.




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9. PASTE MODE - PASTING AND JOINING

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!Jcut's Paste Mode allows you to join an imported JPEG to
any of the 4 edges of a currently displayed JPEG or to paste
it into the current JPEG.

Suitability

  Some JPEGs cannot be pasted or joined and !Jcut performs an
  initial check for suitability before loading a JPEG intended
  to be pasted or joined.

  Obvious considerations are the comparative JPEG block sizes
  and image pixel sizes. Not so obvious is the existence of
  incomplete edge blocks. Images with incomplete blocks on the
  right-hand edge cannot have imports joined on the right.
  Those with incomplete blocks along the lower edge cannot
  have imports joined on the bottom. The presence of
  incomplete edge blocks also limits the extent of the area to
  which an import can be pasted.

  Any JPEG pasted or joined to another will be decoded using
  the tables of the main JPEG. If the tables of the pasted and
  main JPEG differ, this will affect the contrast and colour
  of the pasted JPEG.


Starting Paste Mode

  Drop any JPEG onto the JAW grid (including a selection from
  the JPEG being pasted into) and !Jcut will check it for
  suitability. If it is suitable, !Jcut will go into Paste
  Mode. The grid lines in the JPEG image window will be turned
  off and you will not be able to save, nor carry out any
  process which would change the current JPEG.

  The imported JPEG will not be shown if it is suitable only
  for joining but not for pasting. If it can be pasted, it
  will appear (usually but not always at the top-left) in the
  JPEG image window.


In Paste Mode, the JAW grid becomes the Paste/Join/Abort
interface. The dark greys will all be changed to light grey,
and letters will appear in some of the grid sections:


            -----------------------------
            |       |    JA    |        |
            -----------------------------
            |  JL   |    P     |    JR  |
            -----------------------------
            |       |    JB    |        |
            -----------------------------


      (Don't worry if all the letters don't appear)


Blank grid section...

  Click in any blank grid section to abort Paste Mode.

JA...

  If 'JA' is shown, you can click in that section to join the
  import to the top of the main JPEG.

JL...

  If 'JL' is shown, you can click in that section to join the
  import to the left side of the main JPEG.

JR...

  If 'JR' is shown, you can click in that section to join the
  import to the right side of the main JPEG.

JB...

  If 'JB' is shown, you can click in that section to join the
  import to the bottom of the main JPEG.

P...

  If 'P' is shown, you can click in that section to Paste the
  import into the main JPEG but before you do that, you will
  probably want to position it...


Positioning and Pasting

Because direct rendering of JPEGs is slow, moving the import
image in real time is nigh impossible without flickering or
worse. !Jcut draws a 2-pixel wide border around the import
image and this rectangle can be dragged quickly, the image
being redrawn within the rectangle when the dragging button
is released.

The imported JPEG image is shown initially as near as
possible to the top-left corner of the current JPEG image.
The initial position indicates any restrictions on the area
of the current JPEG to which the import can be moved, i.e.

Case 1: appearing top-left.

  The import has no incomplete edge blocks. It can be moved
  anywhere except over any incomplete edge blocks in the
  current JPEG.

Case 2. appearing top-right.

  The import has incomplete edge blocks on the right-hand side
  matching those of the current JPEG. Movement is restricted
  to the right-hand side and possibly may not include the
  bottom-right corner.

Case 3. appearing bottom-left.

  The import has incomplete edge blocks along the bottom edge
  matching those of the current JPEG. Movement is restricted
  to the bottom edge and possibly may not include the
  bottom-right corner.

Case 4. appearing bottom-right.

  The import has incomplete edge blocks on both right-hand
  and bottom edges matching those of the current JPEG.
  Movement is not possible.

If movement is possible, placing the pointer anywhere in the
allowed area and holding down SELECT will cause the import
outline to jump to the pointer, and moving the pointer
without releasing the SELECT button will drag the outline
around. The image will be drawn within the outline when
SELECT is released. Alternatively, place the pointer
anywhere within the import outline and drag with ADJUST.

The positioned import may be viewed without the outline by
closing the JAW or by changing the grid to the invisible
colour. (see Help Section 4)

When you are happy with the position, click on the JAW grid
section marked 'P' to paste the import into the current
JPEG. The display window will be redrawn to show the new
image.


Remember...

Click a blank JAW grid section to abort Paste Mode.




##############################################################

10. SOME IMPORTANT POINTS

##############################################################


!Jcut works correctly on all standard JPEGs that it has
been tested on. I can't guarantee that it will work on any
strange format JPEGs.

Since !Jcut uses one of the JPEG SWIs in SpriteExtend 0.99
or later, it will not work on RISC OS versions prior to 3.6.

Errors may occur if e.g. there is not enough disc space, or
the medium is write protected. Remember to keep backup
copies of your JPEG files in case you accidentally overwrite
them with a saved out selection.

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

!Jcut uses  the Independent JPEG Group utility 'jpegtran'.

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

RISC OS ports of the other utilities by the Independent JPEG
Group (cjpeg, djpeg, wrjpgcom 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

Web site: http://www.dacha.freeuk.com/




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end of !Help file.
