Long exposures

Since a long time ago I quite like to do exposures while I am taking photos. For those who don’t know what an exposure in photography is here you have a definition from Wikipedia.

In photographic jargon, an exposure generally refers to a single shutter cycle. For example: a long exposure refers to a single, protracted shutter cycle to capture enough low-intensity light, whereas a multiple exposure involves a series of relatively brief shutter cycles; effectively layering a series of photographs in one image. For the same film speed, the accumulated photometric exposure (H) should be similar in both cases.

To know more about it just go to the entire article by clicking here.

Going back to the topic of this post I would like to show you some exposures that I did in my last visit to London where I took my camera for a walk at night (this is something I don’t do quite often but that I like to do from time to time). Usually to do exposures you may need a tripod. In my case I didn’t want to carry with the tripod the whole day so instead of that I was using mainly my camera bag to build a stable surface to put the camera on.

With this small collection of exposures I didn’t want to express movement, which is one of the reasons why people does them. In this case I was capturing a city landscape so buldings, but I wanted to take the colour that I was seeing, so no flash at all to get  the correct amount of light. This fact makes this kind of photos such a challenge because don’t forget that in cities there are many different light sources and in many different colours, so get the light that you want is quite a difficult target.

To find out more go to my flickr gallery.

Editing xml elements with xslt stylesheet

In the last days I have spent some time using xsl to modify my xml messages in run time. Since I saw xsl the first time with the help of Pierre, a friend of me. I realized the amount of different things that you can do with xsl and how power it can be.

So what I have done this days is editing the values of xml and removing elements. So for that I will give you a tip of how to do so.

The source of the example will be this xml.

<?xml version=”1.0″ encoding=”UTF-8″?>
<soap:Envelope xmlns:soap=”http://www.w3.org/2003/05/soap-envelope”>
<soap:Header>
<wsa:To xmlns:wsa=”http://www.w3.org/2005/08/addressing”>http://localhost:7070/WsSongStore/services/WsSongStore</wsa:To>
<wsa:Action xmlns:wsa=”http://www.w3.org/2005/08/addressing”>http://songstore.org/cap/mgmt/CreateOperation</wsa:Action>
<wsa:MessageID xmlns:wsa=”http://www.w3.org/2005/08/addressing”>uuid:fe33274e-1ca7-daca-ceab-13e4417560c2</wsa:MessageID>
<wsa:From xmlns:wsa=”http://www.w3.org/2005/08/addressing”>
<wsa:Address>http://www.w3.org/2005/08/addressing/role/anonymous</wsa:Address>
</wsa:From>
<vSTS:FederationUUID xmlns:vSTS=”http://www.example.com/example-STS”>aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa</vSTS:FederationUUID>
<vSTS:businessKey xmlns:vSTS=”http://www.example.com/example-STS”>1a555434-ca9e-4c31-b59a-dc3c07f6dad1</vSTS:businessKey>
<user:username xmlns:user=”http://www.example.com/ssc-User”>juanlu</user:username>
</soap:Header>
<soap:Body>
<pfx1:CreateOperation xmlns:pfx1=”http://songstore.org/cap/mgmt”/>
</soap:Body>
</soap:Envelope>

And what we will do first is to change the uri of the element to within the header for a different value. And for that we will apply the xsl stylesheet below that what it does is look through the xml tree for the element we say in the when statement and change its value for the one stored in the variable that we declared at the beginning.

<?xml version=”1.0″ encoding=”UTF-8″?>
<xsl:stylesheet version=”2.0″ xmlns:xsl=”http://www.w3.org/1999/XSL/Transform” xmlns:xs=”http://www.w3.org/2001/XMLSchema” xmlns:fn=”http://www.w3.org/2005/xpath-functions” xmlns:soapenv=”http://schemas.xmlsoap.org/soap/envelope/” xmlns:wsa=”http://www.w3.org/2005/08/addressing”>
<xsl:output method=”xml” version=”1.0″ encoding=”UTF-8″ indent=”yes”/>
<xsl:variable name=”fromVirtualUri”>http://localhost:8080/WsSongStore/services/WsSongStore</xsl:variable>
<xsl:template match=”node()|@*”>
<xsl:copy>
<xsl:choose>
<xsl:when test=”local-name()=’To’”>
<xsl:if test=”namespace-uri()=’http://www.w3.org/2005/08/addressing’”>
<xsl:value-of disable-output-escaping=”yes” select=”$fromVirtualUri”></xsl:value-of>
</xsl:if>
</xsl:when>
<xsl:otherwise>
<xsl:apply-templates select=”@*|*|processing-instruction()|comment()|text()”>
<xsl:with-param name=”virtualUri”></xsl:with-param>
</xsl:apply-templates>
</xsl:otherwise>
</xsl:choose>
</xsl:copy>
</xsl:template>
</xsl:stylesheet>

The second transformation removes elements from the xml, may be because we don’t want them anymore in the message because we have used them already and the message that the other component is expecting does not contain them. So the following  xsl loos for the element we  say on the variable that we declare at the beginning and copies everything to the exit but that element, that is skipped due to the when declaration.

<?xml version=”1.0″ encoding=”UTF-8″?>
<xsl:stylesheet version=”2.0″ xmlns:xsl=”http://www.w3.org/1999/XSL/Transform” xmlns:xs=”http://www.w3.org/2001/XMLSchema” xmlns:fn=”http://www.w3.org/2005/xpath-functions” xmlns:soapenv=”http://schemas.xmlsoap.org/soap/envelope/” xmlns:wsa=”http://www.w3.org/2005/08/addressing”>
<xsl:output method=”xml” version=”1.0″ encoding=”UTF-8″ indent=”yes”/>
<xsl:variable name=”tag”>username</xsl:variable>
<xsl:template match=”node()|@*”>
<xsl:choose>
<xsl:when test=”local-name()!=$tag”>
<xsl:copy>
<xsl:apply-templates select=”node()|@*|*|processing-instruction()|comment()|text()”/>
</xsl:copy>
</xsl:when>
</xsl:choose>
</xsl:template>
</xsl:stylesheet>

I hope this helps you.

Cycling in the city (Copenhagen)

Since a while ago I have been looking at different cities and how ready they are to ride a bike on them. During this, almost, 2 years living in UK I have been going to work cycling more than the 80% of the days. My office is around 6 miles (10 km) away from my house in Ipswich. Cycling there takes between 25 and 40 minutes, depending on the weather conditions and the company (usually when you go with more people takes longer due to speaking).  Getting there is quite easy and save as we have a full cycling paths network inside and surrounding the town, so as soon as you can imagine you are inside one of this cycling paths.

Today, by using 4 different videos with true histories of people that lives in Copenhagen I would like to show the people how  easy and comfortable can be to go by bike to work skipping traffic jams, not looking for parking and also because it is increment friendly and healthy for yourself. Copenhagen is a city with more bikes than population and where it is not difficult to see entire families going anywhere by bike, from the dad in the shut that goes to work to the little kid that can either go with his own bike or in a special chair in his parents bike. This makes Copenhagen a place where the bike culture is deeply attached to the people and even if you go just for visiting it makes you feel that you have to ride a bike to know how would you feel in the city, kind of comparable as visiting the monuments and museums of the city.

In comparison with my home town Madrid, where cycling is basically a sport that you might do at the weekend and where if you go by bike in the city most likely you will be going through the side-way (which is illegal) because nobody respects you, where you don’t have spaces special for bikes, where it is almost impossible to combine bike and public transport because of restrictions in the metro for instance… So i wish this changes ASAP as Madrid, with all the hills that it has, can easily improve the quality of live with just a few changes in the infrastructure and car culture that we have over there. Other big cities in Spain have started to change this issue by implementing a hire bike service, where you can get a bike somewhere and drop it in a different place.

Hopefully with the Olympic Games candidature our politicians at Madrid think twice about this issue and act in consecuence.

Right, after all I have said here you can see the videos:

Part 1

Part 2

Part 3

Part 4

Part 5

Intrusion into HDR

This is an idea that has been in my mind for quite a few time already but that until today, a sunny with cloud intervals in the sky I haven’t realized. So this morning, after being doing a few thins I had to wrap up I took my EOS 350d with the 18-55 lens and with my bike I went for a photo ride around Ipswich.

The topic I have chosen today it has been something very tipical in this country, the pubs. I haven’t taken a photo of all of them but I think that as a first approach you can figure out how they are. But let’s focus on the HDR which is what I wanted to try today.

As we can see on Wikipedia, this is a brief definition of HDR: In image processing, computer graphics, and photography, high dynamic range imaging (HDRI or just HDR) is a set of techniques that allows a greater dynamic range of luminances between light and dark areas of a scene than normal digital imaging techniques. The intention of HDRI is to accurately represent the wide range of intensity levels found in real scenes ranging from direct sunlight to shadows.

The way you do it is taking the same picture 3 times at least with a different set up on the camera, meaning that you take a normal photo as if you only want to take one photo of the scene and then you take a high exposure and a low exposure of the same item, therefore it is highly recommendable the use of a tripod when you make this kind of photography. However if it is in daylight and the speed you use is fast enough you can take them without it.

To get the more possibilities and the best marked effect with HDR you must shut your photos using RAW format. Then the image is not compressed and it is easier to handle into a wide range of colours and other settings by the program you use. As the photo is taken in RAW, the weigh of this one is way more than a compressed one in JPG as many people use to take them, so have this in your mind because it is esasy to notice that we are running out of space in the card. To compose the final image that will produce the effect. I have used Adobe Photoshop CS4 in Mac OX to compose the HDR photography. The way you do it is really easy, as the programs does all the work for you appart of the postprocess that you would like to add to the result. I haven’t done anything after that because I liked the result and because I am still learning this work.

There are more examples of my ride into my flickr gallery so I invite you go around and have a look to them

Technics in Street Photography II

Bruce Gilden has been doing street photography for years in New York. He has an special point of view of how street photography should be. He likes portraits more than full scenes, so he goes close to the people with a hand flash and the camera on the other hand. If we compare his way of taking pictures with the one we saw last week, his stile is way more aggressive with the people because of his approach. However the result is awesome. Just qualify that he also sees street photography in Black & White, as Joe Wigfall. Will more people see this photography as it is until now… we’ll find out in future post.

Just enjoy the video of Bruce Gilden working in his city:

Technics in Street Photography

I can show you today how somebody, in this case Joe Wigfall takes his pictures of street photography in New York. The way he shots is by not looking through the camera. Is it easy? Is it difficult? Well… that depends on the camera, the lens that you have on it and how you know it because when you spend a while with your camera you get to know what is in front of it and what is going to be recorded on the ccd or the film.

Ok, once I have said that, here is the video. Enjoy!!

Wich Operating System do you use?

From the begining of the computing we have the chance of choose the Operating System (OS from now on) that is running on our computer. Most likely people trends to use Microsoft XXXX because by default it is installed on their computers, which from my point of view it is a very bad practise from the computer manufacturers because they would give the option to choose this or this other OS that I like. But any way, that is a different story than the one I am targeting today.

In the options that we have also there is GNU/Linux and all the range of different distributions within this OS. Therefore we can choose  the distribution we like because we are more use to it or the one that fits better in our computer or that that has been developed for an specific task that we want to do…

Our third main option is Mac OX for the one that have Apple computers and that people say that when you try this one it is difficult to go back to a normal pc… Well my experience with this system is great and I wouldn’t go back to Windows but GNU/Linux is there.

Each of this three OS has it’s owns pros and cons as in therms of stability, usability, GUI, compatibility… You can read more about this topic in this article of CIO.

However I can see the “new” OS that you, me, us are running and using every day and that it is totaly independent of the one that ir running on your computer and that may be you won’t use it anymore in this last years and that we won’t use anymore going back to the old dummy terminals that were connected to a mainframe. You might figure out by this time what I am talking about, I am after all the services that the big companies over internet are providing to the user. How many of you are using all the google stuf? (google mail, google reader, google docs, blogger, the search engine of course) But not only google, Microsoft has all his enviroment under the name of MS Live that contains more or less the same services as iGoogle. I am saying that because more often when you see the screen of a computer you only see a browser running with several tabs open or serveral windows of the server there, but not more than that, so basically we are running and using Google OS with its services, Microsoft OS with its, Yahoo…

Have you ever notice this? This was planned a long time ago, but now at days it is more explicit than it was before thanks to the popularity of clowd computing, the appearance of the netbooks and the evoluton of cellphones and fast comunications by the new mobile networks.

Street photography

Last friday I started reading in xatakafoto some post about street photography. I have done just a few photos of this kind of photography because I was shy of photography people that I don’k know, but having a look to some galleries I have decided to start a serie of it.

For those that don’t know what street photography is about this is the definition that you can find in wikipedia:

Street photography uses the techniques of straight photography in that it shows a pure vision of something, like holding up a mirror to society. Street photography often tends to be ironic and can be distanced from its subject matter and often concentrates on a single human moment, caught at a decisive or poignant moment. On the other hand, much street photography takes the opposite approach and provides a very literal and extremely personal rendering of the subject matter, giving the audience a more visceral experience of walks of life they might only be passingly familiar with. In the 20th century, street photographers have provided an exemplary and detailed record of street culture in Europe and North America, and elsewhere to a somewhat lesser extent.

Many classic works of street photography were created in the period between roughly 1890 and 1975 and coincided with the introduction of portable cameras, especially small 35mm, rangefinder cameras. Classic practitioners of street photography include Henri Cartier-Bresson, Robert Frank, Alfred Eisenstaedt, W. Eugene Smith, William Eggleston, Brassaї, Willy Ronis, Robert Doisneau and Garry Winogrand.

So to got for this new challenge in my photography hobby I will use my 3 weapons:

1. My phone, as it is small, fits in the pocket and has got a camera, it is a good candidate to use it almost everywhere during the day.
2. My old compact camera, my sony DSC P7 with its 3,2 Mp is good to get this photos when you go out or you are in a concert or go for a ride with the bike wherever and you can find good shots.
3. But the main one is gonna be my digital-SLR, with the Canon EOS 350D I will do most of the work for obvious reason the quality would be better and you can play with more settings than with the other 2 that I have described above. However it is going to be the most difficult one due you cannot hide it and if you take a photo to people you don’t know they are going to notice it, but I have decided to do it and this is one of the risk that you have to assume.

Once I have told you all of this let me show you some examples of this kind of photography. And I hope you enjoy the galleries coming as the ones that are already in my public flickr gallery.

• http://www.streetphoto.fsnet.co.uk/
• http://www.flickr.com/photos/patxiwan/
• http://www.streetphotography.co.uk/

Set up of a xen image

If you want to set up a xen image on a different server than the one you have it running on, once you have copied all the files (image.img, image-swap.img, image-config.img,…) there are some things that you have to have into account.

• Change the config file: the config file has to be according with the new path of the files and you might probably want to change also the way that the virtual image behaves regarding the start, shutdown, or the new network configuration, that might be different if we move network.

But not only changing the configuration file will make our image start correctly, because it can start but with some failures regarding modules dependencies, this can be because when we change the image form a computer to another, if the kernel of the host is not the same as the kernel of the previous host xen server, the modules dependencies wouldn’t be the same and in the “creation” of the image, xen will complain because of this. But there is an easy way to solve this issue it and make xen happy in this step.

• Mount the xen image in a directory by using mount -o loop image.img mount-directory by doing this you can access to the file system of the image as if any other device would it be.
• In the host go to /lib/modules, crate a directory called as your kernel name (mkdir `uname -a`), go inside this new folder and run depmod -a this will create several dependencies modes for your host computer.
• Copy this entire folder into the image it has to be also in the folder /lib/modules and it will tell xen which kernel you have and where to find dependencies for the modules.
• Umount the guest image directory umount mount-directory

Now is when we can start our xen image as we use to do so: xm create -c image-comfig.cfg (-c if we want to see the start console, that helps to see whether if we have a problem or not during the start).

I hope this small tip helps you with the deployment of xen images in different servers.

Create a Xen image.

I have just created my first Xen image.

1. Create a disk image (dd if=/dev/zero of=somefile.img bs=1 count=1 seek=8G)
2. Format disk image (mkfs.ext2 somefile.img)
3. Mount disk image (mount -o loop somefile.img looppoint)
4. Copy your files (tar -zxSf yourtarballingzformat -C looppoint)
5. Unmount your loop (umount loop)
6. Create your swap file (if you want) (dd if=/dev/zero of=xen-swap.img bs=1M count=256) <– no sparse file for this…
7. Create your xen.conf file for that image.

xen.conf…

name            = ‘myvm’
memory          = ‘256′
disk            = [ 'tap:aio:/xen/myvm/somefile.img,sda1,w',
'tap:aio:/xen/myvm/xen-swap.img,sda2,w',
]
root            = ‘/dev/sda1 ro’
vif             = [ 'mac=00:16:3e:22:10:f8,bridge=eth0' ]
on_reboot       = ‘restart’
on_crash        = ‘restart’
vcpus           = 2
kernel          = “/xen/centos_boot/vmlinuz-2.6.18-92.1.18.el5xen”
ramdisk         = “/xen/centos_boot/2.6.18-92.1.18.el5xen.img”

You just need to change the  kernel and ramdisk according to your host computer settings and play it.