PC Plus HelpDesk - issue 271
||This month, Paul Grosse gives you more
insight into some of the topics dealt with in HelpDesk.
From the pages of HelpDesk, I look at:
- Characters without keyboards;
- 3D cloning corrections;
- Running up to speed;
- Locate and format; and,
- Boot and Nuke.
Characters without keyboards
In the past, we've covered how to change your keyboard
so that you can input characters from different areas of
the utf-8 spectrum and you should all be typing using
Gurmukhi characters by now.
However, suppose you only need to input the occasional
character. It wouldn't be worth using a different
keyboard layout each time because there are so many. So,
what is the alternative?
You can use OpenOffice.org's 'Insert',
'Special Character' to put them on the clipboard and then
paste them into your image editor but you need to know
which font they are in and that means searching through
them until you find one (and then, it might not be the
one that you would be happiest with - correct weight or
style?). So, is there an easier way?
Gnome's Character Mapping program ('Utilities',
'Editor', 'Gnome Character Map' - screenshot on the right)
which will run equally well under KDE as Gnome will do
this job for you and being lightweight, takes about a
second to load.
One thing that you will find is that if a character is
not within a particular font, it will be displayed if it
is in any font that is installed on your system - this
gives you the advantage of being able to see what your
system has to offer, without having to search through
every font, looking for a 'Devanagari Candrabindu' or a
'Zhuyin Fuhao' ('Bopomofo') 'Eng'.
Double-click on the character (remember that this is a
Gnome program) and it will be copied to the text at the
bottom of the window.
With this character mapping program, you can edit the
text so if you make a mistake, you can delete the
unwanted parts and double-clicking on a character
actually places the character where the cursor is, rather
than only at the end of the test string.
|Once you are ready, just click on
the copy button. Pasting it into a suitable image editor
will make it select a font that contains those characters
- this is what happens with The GIMP.
If you have a
particular font already identified then just use that.
3D cloning corrections
Using a humble camera, you can create 3D images.
Instead of using a red and green system, you can place
the images side by side and then cross your eyes so that
the images superimpose (the alternative to this is to
relax the convergence on your eyes but this has
limitations on the image size and not everybody can do
So, take an image and then move to the side and take
another. Through the view finder, get the composition you
want and then rock to the left so that your weight is on
your left foot, take a shot and then rock to the other
side so that your weight is on your right foot and take
another shot. By doing this, you can hold the camera
rigidly so that you are not changing the angle or
direction of the shot. By doing that, you are avoiding
having to perform rotation and perspective corrections on
the image when you get it onto your image processor.
The distance you move between shots will determine how
much 3D effect you will get - move around 65mm (roughly
the distance between your eyes - look into a mirror,
holding a ruler up to your eyes and zero it using one eye
and read the distance using the other) and you will
get the same level of 3D effect that you normally see. If
you use a larger displacement, the effect will be
exaggerated. For views where there is little in the
foreground (say, nothing for 10 metres or so) then try
moving twice the normal distance and take another shot at
four times the normal displacement and see what effect
you get when you look at the pictures. One thing to be
aware of is that if you have reflective surfaces (such as
the red handrail in the bottom pairs of images in this
section), you can end up with sets of reflections that
are too different for you to look at comfortably.
You will learn a lot from playing around before you
use the only opportunity you will have to take your
So, this is what such an image pair looks like - this
is InfoSecurity 2008 which was held at Olympia at the end
Cross your eyes so that the images superimpose and
then focus them.
|If you look at the images above, they
seem at first to be identical but on closer inspection,
there are differences. The image on the right - the one
that you look at with your left eye - has a different
view point. The most obvious artefact of this is the 'D'
of 'AND' on the right of the top row in the advertisement
at the back of the hall. However, there are more such as
in the superstructure and so on.
With one image being
for the left eye and the other for the right, you can get
them the wrong way around. Look at the composite below
and you will see that the superstructure behind pokes out
|In the composite below, it is the right
way around. So, we have established that the images have
to be a particular way around and that lateral
displacement is the key to the perception of depth here.
|However, there is another point and that
is if you are using one camera to take two images at two
places, you can't take them at the same time (without an
attachment of some sort). So, anything that moves will
cause a displacement within the image pair that will put
it in the wrong place - a few people moving is manageable
but if you are taking pictures of a beach with waves, you
need to be careful (it's not impossible, just stretching
it a bit - large waves will be virtually impossible but a
small wave breaking should be correctable using the
method below). You will need to correct these differences
if they are too much and the way to do that is by using
the clone tool.
Most of us have used the clone tool to copy
from one part of an image to another but this tool is far
more powerful than that. Even as far back as Micrografx
Picture Publisher 7 (1997) and probably before that, you
could clone from one image to another without having to
make it one image.
On modern Image processors - PaintShop Pro, Photoshop
CS3 and The GIMP - nothing has changed that much. The
only real difference between Photoshop and The GIMP being
that on Photoshop, the layer you are copying from needs
to be made visible (layers dialogue box) in order to use
it as a source.
So, in The GIMP, assuming that you have your stereo
pair loaded up as two separate images. You can, if you
want, create several transparent layers over the top of
the base image so that you can clone onto them instead.
Make the layer in the destination image that you want to
clone to, the current layer. Make the image you want to
clone from in your source image its current layer.
Finally, make them the same magnification, align the two
windows side by side and make sure you can see the same
parts of each.
Next, click on the part of the source image you want
to copy over whilst pressing [Ctrl] and then [Alt][Tab]
to the other (destination) image of the pair.
Align the mouse so that the detail you clicked on in
the source image is in the same relative place in the
image as its depth requires - a static part of the top of
the stairs was used in the InfoSec 2008 image - and then
Remember that for different depths within the image
pair, you need to use a different lateral displacement
so, for the man that is half way up the steps on the
first landing, you need to use a different offset. This
is where using different layers comes into its own. You
can clone to a layer that is below the top (nearest)
layer without overwriting it so that your image remains
Another advantage of cloning to a transparent layer
(as opposed to directly into the base image) is that you
can play around with pixel-sized displacements so if you
make a tiny error in selecting which pixel to clone to,
you can correct it without messing up your image.
If you have a good picture, it is worth the effort.
|Here, you can see the difference between two
images, being the time take between them (one had an EXIF
time stamp of 55:42 and the other of 55:43 so somewhere
between just over one and just under three seconds).
|And, here is the same image after the
You can access these images to have a
play around with them by clicking here (a new window will open up).
Running up to speed
have installed two different pairs of DDR400 memory
sticks, you might have found that even though it says
that each of the sets is capable of working at a data
rate of 400MHz, the BIOS tells you that they are instead
working at a lower rate - in this case, the system thinks
that they are better off running at 333MHz.
The test that we ran in PC Plus last month showed a
measurable increase in speed when they were configured in
a particular way but DDR400 chips running at 333MHz?
This is not what they were bough for.
|So, reboot the machine and press [Del] to
get into the BIOS CMOS Setup utility.
Chipset Features' and press [Enter] for 'DRAM
|Set 'Timing Mode' (the top parameter) to
Manual' by pressing [Enter], selecting 'Manual' and
pressing [Enter] again.
The 'MemClock index value' is
set to 166MHz here so press [Enter] and change the
frequency to 200MHz, remembering this is doubled (DDR
stands for Double Data Rate - the clock is tripped on the
rise and the fall of the 200MHz clock signal so that you
get effectively a 400MHz frequency).
|Reboot the machine and this time, you can
see that it is set for DDR400 (previously, this read
|Everything else in the configuration menu is
set at 'Auto' so nothing should come to any harm - the
memory sticks can work at 400MHz quite easily.
if you feel that you need to tweak the other settings, go
ahead - remember that if you don't actually break it, you
can turn it back.
Locate and format
be familiar with this scenario or something like it ...
You (or a friend at work, a relation, et cetera) tried
installing an OS onto a USB flash drive but it installed
it on the external USB hard drive instead.
The external USB hard drive partitions were deleted
using Darik's Boot and Nuke and now, you (someone else)
can't find the drive on the system anywhere when it is
It refuses to recognise the drive sda. Have you (you
know who) got to buy a new disc?
Well, Darik's Boot and Nuke ( http://dban.sourceforge.net/
) appears to have done a rather good job. However, not
all is lost (although the data certainly is).
The following is for SuSE but you can do the same on
First of all, you need to see which drive you are
using so either press [Ctrl][Alt][F10] to get you to the
message screen or open up a terminal, su to root and type ...
tail -f /var/log/messages
... which will do pretty much the same thing on any
system. Next, plug in the USB drive. With a normal drive
that is formatted and recognised by the system, you
should get something like the output in the screenshot
|However, if you have nuked it, you
should get a message that looks like ...
Apr 29 15:03:02 zircon kernel: sda: test WP failed, assume Write Enabled
Apr 29 15:03:02 zircon kernel: sda: assuming drive cache: write through
... repeated. You now know for certain that your drive
(in this case) is sda - this is important.
If, instead of using a terminal, you used the messages
screen, press [Ctrl][Alt][F7] to get back to your session
(may be a different function key on different systems).
select 'KDE', 'System', 'YaST (Administrator Settings)',
enter your root password. In Control Center, select
'System' and then 'Partitioner'. Click 'Yes' on the
Warning dialogue box. The Expert Partitioner loads.
Select 'sda' and click on the 'Create' button. Select
your drive - '/dev/sda' - and then click on 'OK'. Select
the partition type - 'Primary Partition' - and then the
create dialogue opens.
Select the file system to format the drive with and,
for the reason that it is a removable drive, make sure
the 'Mount Point' is empty (you don't want it searching
for this drive on boot up and then failing to find it).
Click on 'OK'.
Finally, click on 'Apply' and then in the green
warning box, click on 'Apply' and watch it work. For a
120GB USB, formatted with ext3 it can take just a couple
of minutes. Remember that whilst it might look as though
it has stuck at some percentage point of the job, the
busy light is still flickering on the drive.
|Last of all, click on 'Quit' and the job is
done. You might have to unplug it and plug it in again to
see it, depending upon your hardware configuration but
now you have your drive back.
Boot and Nuke
many programs for deleting partitions on hard drives but
most of them need you to have a specific OS or type of OS
installed in the first place. Darik's Boot and Nuke
(www.dban.org) runs from a live CD so that the installed
OS is completely irrelevant.
The dban version 1.0.7 ISO file is only 2.0MB and
version 2.0.0 is 5.7MB - the intention being that it can
be run from a floppy diskette or a USB drive if
To run it from a floppy diskette, download the
dban-1.0.7_i386.exe file and then unzip it using the
unzip command. Next, copy the image file to the floppy
diskette by typing ...
dd if=dban-1.0.7_i386.ima of=/dev/fd0
... and when the light has gone out on the drive, you
can reboot and run the program - remembering that the
floppy diskette should be on your boot list in your BIOS.
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