Fighting with computers

It's been half a year since Canon PowerShot S95 appeared. Today I'm happy to learn that together with a software update to the "crashy" iPhoto '11 comes a software update for new cameras on Snow Leopard .

I was learning OpenCV for a new art project, but then I learned that the new Microsoft Kinect device had been hacked by a Spanish student after the bounty offered by Adafruit Technologies . This news changed it all, as Kinect drivers for several platforms were made available. I needed to extract the silhouette of a person from the exhibit space and having a depth image as the one Kinect provides made my job ten times easier. The previous plan was to keep an image of the background and substract the current frame from it to detect changes. But handling changes in lighting conditions was a bit challenging. What Kinect provides is a regular color (or infrared) webcam plus a second camera that measures depths (ie. each pixel brightness represents the distance to the kinect of that scene point). If you want to isolate object from an scene that are at a certain distance from the camera, all you need to mark those pixels between a certain value range on the depth image. Simple,...

I had some funds to kill and I thought a new small laptop running Windows 7 would help me not to be a total illiterate when it comes to whatever changes come with W7. I wanted to replace my old Acer Travelamte 3002 WTMi that served me well (though loudspeakers failed almost from day one). A quick look around the web showed that Dell M101z model could be a good choice: good value, acceptable battery time, small and not too heavy. I've never bought from Dell before but I guessed it won't be difficult or unpleasant: I was wrong. First of all, I wanted Dell to produce an invoice to the name of my employer. I contacted with Dell chat (sorry, not available over the weekend) and I asked them for help. I was provided an email of a Dell representative dealing with my employer. I sent her an email and waited. After 24h with no answer, I contacted Dell chat again asking how long should I wait to get an answer, as this being my first time with Dell I was not aware of what the typical servi...

A recent art project requires to do some image processing. This topic is a bit away of what I use to do so I asked around what was available now. Some people suggested me to use OpenCV , which is an open library for Computer Vision projects. I realized that Processing also had some basic features for real-time image capture. Even better, I learned that there was a version of OpenCV available for Processing . The reason of using OpenCV from Processing instead of directly programming in C++ is the easy setup you have with processing. If you have a PC or Mac the use of the system webcam is very easy. For Linux systems it is slightly more complicated. OpenCV makes very easy to do thinks like detecting faces on the image, which is quite funny. There is this book about OpenCV too.

Once I realized I needed to sync my iPad to pass every tiny file to it though iTunes I was not happy. So when I learned there was a Dropbox version for it that was free I saw an opportunity. Later, I found out that there were dropbox versions available for Linux, OSX and, of course, for Windows. A bit later, I learned that even there is an app for my trusty Nokia E71 so I can upload picture to a dropbox folder right away. Since then I've almost stopped using a USB pendrive in favor of dropbox and till now, the server has been great. In a nutshell dropbox is a shared folder on the web plus an app on each computer that syncs the content of your local folder with the copy held on the Internet. Any file you add or change is modified on the network storage. To put the icing on the cake there is also a web-based access to your data, so if you're visiting a friend or using a lab computer you cannot install software on, you still can access your dropbox account files. Basic service is...

One of the features that came with Java 6 is this neat trick: You can have a Javascript runtime on your Java program. You feed it with Javascript code and you can get the value of the variables. It looks great if you need to use some logic already encoded with Javascript and you need to include it in your Java program. No rewriting is needed then. I've done a sample program to evalaute a simple arithmetic expression as the first command line parameter of this Java program .

Just for testing it I installed the new iLife'11 on one of my systems. I mostly use iPhoto and I was happy with iLife'09. What I can see now is that iPhoto look has changed to be more similar to iMovie on the user interface. Some floating menus (like photo adjustment) are not embedded on the application window and general look is worse IMHO. But this is not the only problem. Calendars are no longer available on iPhoto, so it seems they will be back soon . The worst thing, however, happened when I was using the new iPhoto: Suddenly my system stopped responding to mouse click or keyboard. Pointer still moved with the mouse but that was it. I suspend the system and when restarted I've just got a blue screen. I power it off by holding the power button for a few seconds. On the next power up they system asked me if I wanted to send a report to Apple, which I did. Whether this was caused by the new version of iLife or not, I do not know. But my system has been running rock solid ...

Remote access is a cool feature, whether you are (still?) using telnet to remote desktop protocol it is something that is very useful. If you are like me, from time to time you get a phone call from a friend asking for help. Of course her explanations hardly match what you picture in your mind, so many times you cannot help them. If you plan on supporting someone online you can install and configure the computer and networking gear (broadband router?) so you'll be able to connect to that system in the future when there is trouble. Many different solutions can be used, but most of them are OS-dependent. You can do lots of cool things with SSH but mostly on a Linux or OS X system. Microsoft includes the RDP tool for remote desktop access to Windows computers. I've heard about TeamViewer before from a client, but given it was a Windows-only solution I did not pay many attention at the moment. I've recently learned that many interesting choices were available: iPad & iPod ...

I recently learned about an embedded design contest jointly organized by Circuit Cellar Magazine and NXP and mbed . I signed in and I've got lucky as I've got one of the free development units. Having used Arduino platform before I was curious about how easy this thing would be. Fear no more, I was setup in a moment. The funny thing developing with mbed is twofold: On the one hand, your computer will see a new flash storage drive when you plug in mbed. On the other hand, no compiler is installed on your computer. Instead, you use the mbed web. They host the compiler through a web interface. Once your code is compiled you just download the binary code to the flash drive and (now Arduino fans can smile) you manually press reset button for your code to be run. I guess many complaints can be made if you dissect the service EULA, but definitely this way of working comes with many advantages too. Being multi-platform is not one of the least important ones. Now I have to think abou...

I've been using computers for quite a while and one of the things I like is to play with them. Since Apple moved away from PowerPC processors to Intel x86 processors many people thought we will soon have OS X on our PC hardware. Being Apple a hardware company, they have few reasons to make that happen (or so they think and act upon). A few attempts from small hardware manufacturers of offering hardware that allows the install of OS X have faced a lawsuit that more or less kicked them out of business. Some other people just made that same thing just for fun. What they call hackintosh computers are PCs running OS X that has been install after a more or less "hide and seek" game with several DVDs. You need determination and the right hardware to get it working. Many times, a software update prevents your system to boot up next time. As a challenge it might be fun, but there is no fun on discovering your work is buried inside a system you can no longer boot-up. So the use...

I liked the idea of a new tracking device. I guess some time using the iPad gave me the wrong idea on what it could feel like to have a similar interface as a mouse replacement. The same day I received an email from Apple stating the new Magic Trackpad was available I rang a local shop to see if they have it. I was told that because it was announced today they did not have it. That I should wait a few weeks before they would have it. Weird. Anyway, after the summer holidays I wanted to switch one of our iMacs to wireless keyboard and mouse so after being turned down in one Apple shop (a different one), where again I was told I will still have to wait an unknown amount of time (not very helpful direction). Hopefully, I stopped by a third shop where I bought a Bluetooth keyboard and a Magic Trackpad. Trackpad is ok but not magic. For the same money I would suggest anyone to go for a Magic Mouse. It is not that the trackpad does not work, but I've found much more convenient to use the...

The Canon PowerShot S90 I've bought a few months ago had a problem . I had to sent it back to Canon to be serviced. I was unlucky and after more than two months waiting I complained to Canon. It transpired that a new part was needed for the repair. My long wait was rewarded with a brand-new PowerShot S95 instead. Even the seller (I bought it on eBay) was so ashamed about me waiting that long that gave away a 4GB SD memory too. Have a look at this analysis .

I was very excited by what this company was about to deliver. But unfortunately they have cancelled the launch of their QUE electronic ink device. In the mean time, Amazon and Barnes & Noble get into price fight that drove down the prices of their entry-line ebook readers to around $140. This is around halve of the original price and what is better, more features are added to the new devices (ie: wifi). I really like the new Kindle 3 and over the summer I've been reading a lot on my 6" Papyre ebook reader. I've come to the conclusion that 6" is more convenient than the larger size of Kindle DX for reading novels. I'm kind of disappointed with KDX as it is not good for letter-size documents (or A4-size) in my opinion. I've used a lot our iPad over the summer but just for browsing and, more importantly, to use the Maps application to find where to have dinner or to look for the route to a destination (very handy when travelling). However I've read no...

A few days ago I received a letter from Amazon stating a new firmware was available for Kindle, and that those with coverage problems with Whispernet could get the update file from the web too. Firmware update for Kindle is supposed to be quite a straightforward operation. First, update file is downloaded to your Kindle, either wirelessly or manually by the user, to the main folder of the system. Once in there, either because user request or automatically, update process starts. I've done this before and no trouble happened then. This time was different, though. I mentioned on a previous post that I've played with the USB networking hack, that enables network access to the Linux system running in the Kindle. I did some tests, set the correct system time on my Kindle and forgot about it. Now that I was trying to update from version 2.3.4 to the new 2.5.2 version I was stucked. Update process stated normally, and "stage 1 of 3" was shown on the lower right corner of the...

I've been researching the topic of how to get prepaid data cards for an upcoming trip to Finland. It is said that Finland is one of the cheapest and most competitive wireless communications markets. Contrary to most people, I just need a temporary solution to get our iPad working while on the go. While most hotels and cities (i.e. Oulu) do have free wifi, I was looking for an alternative to the outrageous roaming cost of Movistar (from 4 to 10 EUR per megabit). Saunalahti offers a seven-day 4 Mbps data plan for 6.90 EUR. I thought my problem was solved. But just in case, I asked customer service. I learned two things that were a problem: In order to activate the card an SMS had to be sent. Unfortunately, sending an SMS is not one of the things Apple decided you're entitled to do with your iPad. Saunalahti is reserving microSIM cards for contract customers, so if you want pre-paid and microSIM you're out of luck with them. (Apparently you might get lucky in an...

I'm a subscriber (and sometimes an author too) of Circuit Cellar magazine. I use to buy it in print format but a few years ago they made the switch to electronic format. Despite the well-know blues about piracy, they chose PDF files with no particular DRM built in. Since then I'm a paying customer. While I was disappointed with the way the PDF was rendered on Kindle DX, I'm happily surprised that the magazine looks quite nice on iPad. And given the zoom capabilities and the instantaneous response of the device to pan actions I can say it is a very nice experience to read the magazine with it. The only caveat is that sometimes it freezes for a while when browsing the pages quickly. I guess it takes a while to render next page and iPad has limited both computing power and RAM memory. How to get the PDF file on the iPad is also not obvious. Though there are several PDF viewers for iPad, the ones I've tried do not allow me to add the files I want to view. However, iTunes so...

I've been reluctant to give in to the latest Apple gizmo. I tried it out last week and it was ok. Web browsing was smooth and comfortable till you reach a flash based page (flash does not work out of the box). The best feature I noticed was that it dos not get hot. This is very nice when the weather is hot. Writting tris entry using iPad keyboad proved not to be very convenient, as many words get replaced by others guessed by Safari to be what I want to write. Maybe it is causes by a mismatch between my localization and writing in English here. A simple post like this took me ten minutes and lots of backspace.

Apparently, Getty Images is a company that sells stock photos. The same company you can accept on Flickr to represent your photo portfolio. As such, it is believed Getty Images make they money by selling stock photos to their costumers, either end-users or designers that use them on their customer's projects. As any other company dealing with intellectual property, they may have copyright infringement cases every now and then. But here is where the innovation comes: Instead of sending a cease and desist letter to those believed to be infringing upon any right owned by Getty Images, they will just send a "settlement demand letter". The whole purpose of that document is to (1) notify the alleged infringement, (2) to act as an invoice for the amount they claim it is worth the damages for the previous use of the infringing images (3) to provide erroneous legal claims to confuse addressee (4) to rush recipient to pay without a second thought (5) to offer the licensing of the ...

Now that the classes are over and I'm thinking about a summer trip I've got myself a new camera. Two years ago I was impressed with Panasonic DMC-LX3 camera but I did not buy it as I've just bought a DSLR by then. Last night I was checking prices on eBay and I saw a good deal for a Canon S90. I checked its features and it turned to be Canon's answer to Panasonic's LX3. It also has a nice F2.0 lens with more zoom than LX3 (28-105mm), a 10 Mpixel sensor and a nice 3" display. It has plenty of manual control and a myriad of shooting modes too. And it is compact, a bit more compact than LX3. I was not planning on buying it but apparently nobody else was interested on bidding and below $300 it was a steal. My first experiences with the camera are good. Not really sure about the best way of holding it as it is quite small. The worst part is the wrist strap that does not seem to fit nicely. She will explain all the basics better than me.

This project is a 5x5 RGB color matrix controlled by an Arduino processor. However, I've used my own RGB controller I mentioned on a previous entry of this blog. Being controlled by serial communications I was able to develop the project on a computer and to try the different light patterns (I used Processing for this). Later, I transfer the code to an Arduino (Processing and C++ syntax are quite similar so it was easy to adapt the code). Details can be found here .

In case you didn't know, OS X and Linux now have Google's Chrome 5.0 browser available . My first impression was good till I was writing this post. Then, an oops screen was shown while editing this message with Blogger (I think it was when switching from HTML to preview mode). Anyway, browser seems to work nicely. It seems fast, imported nicely my password database,bookmarks and digital certificates from Firefox. Flash worked ok too. I've only got a minor problem with Vimeo videos that do keep the browser window on top of the full screen video when switching to full-screen.

Last time you used tweezers they were made of steel, weren't they? Well apparently there are " other ways ". I think that a video will explain it better than my words. In the videos small (reflective) smoke particles are captured by the laser beam.

I've just qualified for Round 1 on CodeJam 2010. I've found the exercises interesting but I was stuck with Fair Warning and I failed the large problem set for the Theme Park. Snapper Chain was the easiest (IMHO) as far as you saw the connection with binary numbers. One more year I'm ready to bite the dust on Round 1. Update : Yep, as expected I failed to move beyond Round 1. I solved two first problems but failed the large data on the second because of my insistence to use int instead of long integers.

Several times I've blogged about Inkscape vector drawing software and its many uses. Being free software there is nothing to lose if you want to try it out. I use it on Windows, Linux and OSX happily. For a new project I wanted to get a given drawing animated and maybe with a soundtrack. My goal was to use this for explaining some topics of my lessons. Long ago I saw LectureScribe and I liked it. But it was not exactly what I was looking for, though you might want to give it a try too. What I am showing you below is a rough demo (no music so I won't get any damn DMCA notice; yes I know there are copyright free music). I've used a Python script by Ed Halley to get a sequence of photograms. Next I've used mencoder to combine them to create a video I later uploaded to youtube. It's a drawing of an stepper motor interface. In case you wonder, I captured this drawing using a Genius G-note board.

A while ago I wired a 25-pin parallel port socket with three resistors to build a parallel programmer for burning Arduino bootloader on brand-new chips. I used several times and it was great. However I do have the need to use it now and I cannot find it. I've bought an ATMega328 as a drop-in replacement to have more memory available for a project involving the Ethernet shield and UDP networking. Unfortunately, Arduino Mega does not have the proper pinout for the Ethernet shield, so the ATmega328 is my best choice. But the new chip I've bought was empty and I need to burn the booloader. I do keep my old PC available just in case, but my new iMac does not have a parallel port either. So I remembered that there was another way of burning the bootloader with some extra wiring on a Diecimila board. And the wires go to the ICSP header ... This way the FTDI serial chip can be used to burn the bootloader in the flash memory of the ATmega. However, it is not as easy if you are not us...

A recent project required to create a matrix of RGB leds. First prototype was set to a 5x5 matrix. For quite some time I've been thinking on the cheapest and more powerful way of doing this. Other people already answered the question in different ways. Either they put a micro controller on board, like BlinkM or they use a PWM shift register like ShiftBrite . A while ago I learned of a website with several PIC-based projects in the same line, one of them it was a serial addressable RGB led controller . One of the factors I was taking into account was cost. When you are using a large amount of units the unit cost becomes important if your budget is limited. I decided I wanted to create my own device. Should I chose a Microchip micro controller I could use the software mentioned above. My fist take was to use a 12F675 8-pin micro controller I found for $1 each on eBay. Unfortunately it seems too limited for the task of handling 3 PWM channels and serial communications as it lacks o...

When my EPSON 830U decided not to work for me anymore (printing heads clogged) I thought I could make some use of the still working mechanics of the printer. It's based on a couple of stepper motors for both axis of motion (print head and paper feed). So I replaced the original power supply and drive electronics for an arduino board and an stepper motor driver from Adafruit industries. Now I could move the printhead anywhere on a page. Next step was to add a laser on the printhead and to control it using a PWM output from arduino (so laser power could be modulated from the computer). Though it only cut thin back color cardboard, it has may uses. I wrote a C program for arduino to control the stepper motors and laser. It receives data from the computer and interfaces with the old printer guts. Data format is very simple: each line contains a sequence of integer numbers separated by blank space. Each pair of numbers represents one XY coor...

Next time you see a broken DVD writer unit, do not throw it away. It contains a powerful visible LED laser. Some lasers used for CD-ROM writers are infrared and, while powerful, the light emitted is not visible, making it both, staying safe and focusing it, more difficult. In order to achieve some impact on a dark surface you need to give a decent amount of electric current to your laser LED (from 150mA to 300mA or more) and, besides, you need a lens to focus the beam. Focusing is important so as to concentrate the beam energy on a small spot (like you do with a lens and the sun light to burn a spot on something). If you are disassembling a DVD writer, you may look for the focussing lens too. If not, you can get one like this . Some guys did make what they called a $50 laser cutter , sounds cool. I'm retrofitting an EPSON inkjet printer to do a similar thing.

You may have heard of Reprap , the 3D printer that prints itself, but if not, I'm sure it'll make you curious. The idea of 3D printers is that you can "print" 3D objects you've designed on a CAD program. Reprap printer or MakerBot are machines that can create 3D plastic objects by fusing plastic into small plastic spaghetti (that adheres itself while hot) over a movable table. Objects are created putting one layer on top of the other. Given the fact that you can print 3D plastic objects, Reprap project went on to do design in such a way that a finished Reprap printer would be able to print all the plastic pieces to make a new one. Unfortunately metal parts and electronics still need to be bought elsewhere. Care has been taken to provide open specification for all the components so anyone can build their own easily. Reprap first version was named Darwin (shown in the picture) but a new version is out, named Mendel , with many improvements, smaller footprint ...

I've been interested on the possible uses of RGB LEDs for quite a while. The underlying logic is pretty simple: Pulse Width Modulation can be used to control the luminosity of each color, giving as a result a similar system to how pixel color is controlled in any RGB display. While creating a LED-based screen is possible and it's being done commercially, the size, power consumption and dot size make it only useful for large screens for sports or music events. At a smaller scale this same technology seems cool for arts projects. The problem is that while many microcontrollers can do PWM, they have a limited number of outputs, and three of them are needed for each led. Alternatively a matrix-like is possible for controlling arrays of RGB LEDs, but sacrificing its maximum luminosity. Searching around the net several solutions pop up: serially addressable LEDs using one microcontroller for each LED, a serial-register-based RGB LED controller and an I2C-bus RGB LED controller .

Just as Google seems to be facing some trouble with EU regulators , my (till now) trusty Gmail account started to give me trouble too. I started a thread on Gmail help forums a week ago complaining of a sudden and weird problem. It turns out that many people are reporting a similar problem. A cool feature of Gmail is that you can fetch emails from other accounts supporting POP3 access. It has been working great for a long time, with the added benefit of using Gmail's spam filtering on that other account's emails. Unfortunately, starting two weeks ago, Gmail stops fetching emails from these other accounts for no good reason. While a fix has been posted: save the affected account settings again, this fix does not last long and problem eventually reappears. While it might look like certain ISP is to blame, given the different and varied error reports it looks much more likely that trouble is in Gmail systems.

Recognizing the big amount of energy being wasted at my university, a system for waking up a computer has been set up. In the past many people, including myself, had no other choice but to leave the computer on if you might want access it remotely (as directed-broadcast is not allowed on campus' network, there was no way to send a Wake-On-Lan magic packet from outside of campus). The new system put in place allows users to wake up their computer from the university intranet, which is a big plus. Alternative systems were available but only worked on certain subnets and you need to know you computer's MAC address (something I have to tell you I've never been able to memorize). However, and there is always a catch, I realized my computer (an ASUS P5G33) did not seem to accept the wake-on-lan feature . I am quite doubtful about following the advice I read on a forum, even more if it requires reflashing my motherboard BIOS with a firmware many tools refuse to accept. However, ...

As I mentioned a few days ago a talk by Richard Stallman was held on campus and I decided to go. The talk was along the lines of the four freedoms (kind of Stallman's version of Asimov's three laws of robotics). But almost at the end of the talk and before the questions he invited to another unannounced speaker who had some rants about the university. Everyone is entitled to her own opinion but this was not the reason why I was there so I left. I cannot comment on that other speaker merits but it felt like a commercial in the middle of the talk (and keeping you there from leaving if you wanted to listen the question). Should that individual have announce his speech people might have decided whether they wanted to attend or not, but the way it was done it felt like a trap. What it may be relevant here is that the university was providing a conference hall for free based on the idea Stallman's speech was of interest for our student and faculty. As expectation was building u...

I've upgraded my main desktop machine to Ubuntu 9.10 and one of things I need to get going is VMware's VM Player. I've been pleasantly surprised to discover that the new 3.0.0 version of wmplayer does include a new feature to create new virtual machines. While I had no complaint using easyVMX site I am extremely happy of having this new feature, previously only available on VMware Workstation product. So, thanks a lot VMware.

Next week, Richard Stallman will give a talk at UPV campus (Conference Hall at building 1H ) on Thursday February 4th, at 5:00pm. Richard has already visited UPV before and can speak Spanish, so I guess that is what he'll use. His views about the software development and ethics are all but conventional. But now that the free sofware concepts have spread open wide many people share many of his points of view. Not sure, however, if Richard still thinks the Copyright Levy (canon digital) we have in Spain now is fare.

Heating and air conditioning are the cause of much trouble on campus. Yesterday I was asked to make a decission as it was believed one of our buildings was too hot because of the sun. But, as I'd like to make my decissions based on facts I decided to setup a temperature logger. As heating is off on Sunday (but Sun is only off at night) I'll be able to compare the temperature profile of Sunday against all the other days when the heating is on. Unfortunately no data logger was available so I set up my own one using three simple elements: An arduino board (actually it was an iDuino I had lying around) a Dallas Semiconductor (actually now part of Maxim IC) DS18B20 digital temperature sensor and a PC. I adapted some code I borrowed from Nuelectronics to read the temperature and I transimted to the PC over the serial port. On the PC side (my office PC is running Windows) I had to program it using VisualStudio, so I created a simple VisualBasic program , whose only purpose is to add...

During the last holidays I've been playing with a new Linux board that I've found quite interesting. It is an open project developed by a Spanish company which in turn enriched the Beagle Board idea with a lot of cool hardware: wifi, Ethernet, Bluetooh, RS-485, LCD controller, etc. They both share many other interesting peripherals as 3D accelerated graphics board featuring HDMI output, microSD memory socket, audio I/O and DSP,USB port, JTAG port etc. The so called IGEPv2 (not sure it is a good name as I find it quite difficult to remember, maybe I'm aging) is a cool piece of hardware that comes with a Linux distribution name Poky and it based on an ARM Cortex-M8 processor running at 720Mhz that needs less than 3 watts for the whole system. It can run Ubuntu and many other ARM-based Linux distros. And it costs 140 Euros, which I reckon it is a sweet price. Put it together with a large HD display and you have a point of information for the public. You may even hide the car...

It seems you can pre-order an International version of Kindle DX from Amazon. Same price as US version. In another front there seems to be more players to the "larger" ebook format, the Skiff and the QUE showing off. But, while some demo new ideas , it seems Apple is about to surprise us (ok, maybe not) with a real device by the end of the month.