Steerable filters generated with hypercomplex wavelets

27 Nov 2007

The publication Steerable Filters Generated With the Hypercomplex Dual-Tree Wavelet Transform is available for download on the Digital Commons Repository of Sheffield Hallam University.

Hornetseye-0.20 released

02 Oct 2007

I have released version 0.20 of the Ruby extension HornetsEye. The new release comes with an implementation of the Dual-Tree Hypercomplex Wavelet Transform. The DHWT is useful for filtering 2-D signals.

Picture of hypercomplex Wavelet decomposition

And God said ...

10 Sep 2007

And God said

Kubuntu and Vista on HP laptop

02 Aug 2007

Ignore this if you are not setting up a HP laptop right now. This is only for anyone who is looking for helpful information about installing Kubuntu on a HP Compaq nx7400 notebook with Windows Vista Business (dual boot). It may be similar on other laptops and with other versions of Windows Vista though.

HP Compaq nx7400 notebook

Backup and installation

The laptop has a 80 GByte hard disk. Initially there is a 20 GByte partition with Windows Vista Business installation software on it
On booting up the first time, the Windows Vista software is personalised and installed on the hard-disk.
After Windows Vista is installed, HP’s backup software automatically creates a backup on the hard-disk and you end up with three partitions: the windows partition, a recovery partition, and another partition with the recovery boot-loader.
To be safe you can boot Kubuntu from DVD and create a backup of the master boot record, the partition table, and the first partition if you have a large external hard disk for example (alternatively maybe you can use the HP backup tool to create a backup on DVDs, but I am not sure about this):

dd if=/dev/sda bs=512 count=1 of=/media/disk/sdavista.mbr
fdisk -l /dev/sda > /media/disk/fdiskvista.log
dd if=/dev/sda1 of=/media/disk/sda1.img
# This will take some time

In the “Control Panel” under Windows Vista, you can find the partition manager under the advanced tools. I deleted the second and third partition (the backup). This doesn’t harm Windows Vista itself. Furthermore I shrank the system partition using “Shrink partition” to the allowed minimum size of 40 GByte.
Now it was possible to install Kubuntu. The Kubuntu installation even allows you to further reduce the size of the Windows Vista partition (e.g. 25 GByte). Don’t forget to install a daemon for CPU frequency scaling such as cpudyn or powersave.
Using dd (see above) one can now create a new backup of the reduced first partition (sda1.img):

dd if=/dev/sda bs=512 count=1 of=/media/disk/sdalinux.mbr
fdisk -l /dev/sda > /media/disk/fdisklinux.log
dd if=/dev/sda1 of=/media/disk/sda1.img
# This will take some time

It can be useful to store the backup files on the Linux partition as well. One can use gzip to compress the img-file. To save disk-space you can compress the backup image on the fly:

dd if=/dev/sda1 | gzip -c > /usr/local/share/sda1.img.gz
# This will take quite some time

Restoring from backup

If Windows Vista is corrupted due to some software problem, now one does not need to have the external hard drive for restoring Windows Vista at hand. You would restore the content of the Windows Vista partition like this (I did not try this!):

gunzip -c /usr/local/share/sda1.img.gz | dd of=/dev/sda1
# This will take some time

One can use the information in fdisklinux.log using the command fdisk /dev/sda to manually restore a partition layout. The mbr-files can be used to restore a particular master-boot record. The img-file can be used to restore the 25GByte Windows Vista partition.

All this information is given without any warranty. You can send me an e-mail if you find that the information is wrong.

Note that if you uninstall the HP backup tool, it will overwrite the master-boot-record of the hard disk (without confirmation) and you will have to reinstall grub (see reference below).

Update:

Dabs is now known as BT Shop.

See also:

Compiz Fusion - Some early results

27 Jul 2007

After a lot of work to merge the free software projects Beryl and Compiz here are some early results of the new plugin manager called Compiz Fusion. The video is really impressive:

Jan Wedekind