Tutorials – Antonio Roberts

Category archives: Tutorials

Streams of data

01Feb10

One of my overall goals is to find a way to databend live video. I’m sure there’s a way to do it with Processing and Pure:Data but I’m not yet proficient in those programs so they’re out of the question for now. In the meantime I thought to try and hack the Echobender script to databend my webcam images.

tonyg provides a great tutorial on how to convert live webcam images into audio, which I’ve used as a starting point for my hack.

The process for making it works is as follows:

Images from the webcam are saved to the computer
These are converted to a .bmp file then renamed to a .raw file
Sox applies an audio effect to the .raw file
The .raw file is converted back to a .bmp then to a .jpg
The updated webcam image is displayed to a window and updated once every second

Sound overly complicated? It probably is. Like the Echobender script you’ll need ImageMagick and Sox but we’ll also be using Webcam, which you can install via “sudo apt-get install webcam”

If you haven’t already, create a file called “.webcamrc” in your home directory (/home/yourusername) and enter this text into it:

[grab]
delay = 0
text = “”

[ftp]
local = 1
tmp = uploading.jpg
file = webcam.jpg
dir = .
debug = 1

Now create a file called grabframe, place it in your home directory and fill it with this:

#!/bin/sh

while [ ! -e webcam.jpg ]; do sleep 0.1; done
convert webcam.jpg frame.bmp
cp frame.bmp frame.raw
sox -r 482170 -e u-law frame.raw frame2.raw echos 0.8 0.9 5000 0.3 1800 0.25
convert -size 640x240 -depth 4 rgb:frame2.raw -trim -flip -flop output.bmp
convert output-0.bmp output.jpg

To start things running, open up three terminal instances:

In shell number one, run “webcam”.
In shell number two, run “while true; do ./grabframe ; done”.
In shell number three, run “display -update 1 output.jpg”

Voila!

I know it’s quite slow, but I haven’t yet found a way to update faster and it’ll still be restricted by the time it takes Sox/ImageMagick to perform their conversions.

Thanks again to tonyg, Imbecil and Mez for their help and inspiration

Filed under Tutorials| Tagged data, databending, glitch, imagemagick, live, sox, stream, webcam | No Comments

Databending using Audacity

16Nov09

Thanks to some help on the Audacity forum I finally know out how to use Audacity to databend. Previously I’d been using mhWavEdit, which has its limitations and just doesn’t feel as familiar as Audacity. From talk on the various databending discussion boards I found that people would often use tools like Cool Edit/Adobe Audition for their bends. Being on Linux and restricting myself to things that run natively (i.e. not under Wine) presented a new challenge. Part of my task was to replicate the methods others have found but under Linux. My ongoing quest is to find things that only Linux can do, which I’m sure I’ll find when I eventually figure out how to pipe data through one program into another!

Here’s some of my current results using Audacity:

Just so you don’t have to go trawling through the posts on the Audacity forum here’s how it’s done. Before I show you this it’s probably better if you work with an uncompressed image format, such as .bmp or .tif. As jpgs are compressed data there’s always more chance of completely breaking a picture, rather than bending it. So, open up GIMP/your faviourite image editor and convert it to an uncompressed format. I’ll be using this picture I took at a Telepaphe gig awhile back

Next, download Audacity. You don’t need the lame plugin as we wont be exporting to mp3, though grab it if you plan to use it for that feature in the future. Once you have it open go to File > Import > Raw Data and choose your file. What you’ll now be presented is with options on how to import this raw data, which is where I would usually fall flat.

Import Raw Data

Under Encoding you’ll need to select either U-Law or A-Law (remember which one you choose). When you choose any other format you’ll be converting the data into that format. Whilst you want to achieve data modification this is bad because it’ll convert the header of the image file, thereby breaking the image. U/A-Law just imports the data. The other settings do have significance but I wont go into that here. When you’re ready press Import and you’ll see your image as data!

Image as sound

Press play if you dare, but I’d place money on the fact that it’ll probably sound like either white noise or ~~Aphex Twin~~ glitchy goodness. This is where the fun can begin. For this tutorial select everything from about five seconds into the audio. The reason for this is because, just like editing an image in a text editor, the header is at the beginning of the file. Unless you know the size of the header and exactly where it ends (which you can find out with a bit of research), you can usually guess that it’s about a few seconds into the audio. The best way to find it out is to try it out!

Anyway, highlight that section and then go to Effect > Echo

Apply the echo

Leave the default settings as they are and press OK

You’ll see that your audio has changed visually. It still wont sound any better but the magic happens when you export it back to an image file, which is the next step.

Once you’re happy with your modifications go to File > Export. Choose a new location for your image and type in the proposed new file name but don’t press save just yet. You’ll need to change the export settings to match the import settings.

Change the file format to Other Uncompressed Files and then click on the Options button.

Export settings

Change the settings to match the ones above (or to A-Law if you imported as A-Law). With that now all set you can now press Save! If you entered a file extension when you were choosing a file name you’ll get a warning about the file extension being incorrect, but you can ignore it and press Yes. If you didn’t choose a file extension, when the file is finished exporting, add the appropriate extension to the file. In my case I’d be adding .bmp to the end.

Here’s the finished image:

Freaky!

There’s of course so many different filters available in Audacity, so try each of them out! If you’re feeling really adventurous try importing two or more different images and then exporting them as a single image.

Filed under Tutorials| Tagged abstract, Audacity, data, databending, experimentation, File format, Filename extension, glitch, Graphics, Image file formats, linux, osx, Ubuntu, windows | 1 Comment

Making a Disco Ball using Blender and Inkscape

01Oct09

Awhile back I started doing a few experiments using Blender and Inkscape together. One of my creations from this was a ball.

Recently one Inkscape user created a tutorial describing how to make a disco ball directly in Inkscape. Looking back at that ball that I made it kinda resembles a disco ball, so I decided to write a tutorial on how I did it.

This tutorial assumes that you know at least something about Blender and Inkscape. If not, go look at these tutorials for Inkscape and these tutorials for Blender. As with any program, the more you use it, the better you get at it.

We’re going to need three things before we begin. First install Blender. It’s available for Mac, Windows, Linux and probably any other system you can think of. Did I mention that it’s completely free? Next, install the VRM plugin for Blender. This is a free Blender plugin that allows you to export your Blender objects as an SVG (the file format that Inkscape uses by default). I’ve discussed the usefulness of this plugin before. Lastly, install Inkscape, if you don’t have it already. I’ll be using a beta build of 0.47, which should be officially coming out within the next two weeks. If not, just grab a beta build as it’s pretty stable.

Once you’ve installed these programs open up Blender and you’ll see the cube on screen.

The cube is usually the first thing you see.

Depending on how best you work you may want to switch to Camera view. You can do this by either clicking on View > Camera or pressing Num0 (the 0 key on the keypad). What we now see is what the camera sees. If you were to export this as a jpg or SVG this is the angle that you’d see it from.

oooh, shiny 3D!

We need remove this cube and add a UVsphere to the screen. Right-click on the cube and press X or Del to delete it.

Bye bye cube!

To add a UVSphere, in the main window press the Spacebar and then go to Add > Mesh > UVSphere.

Add a UVsphere

You’ll now see another dialogue box asking you to specify the rings and segments. This is important as it’ll define how many tiles there are in your disco ball. Think of these options in this way. The segments option is like the segments of an orange and cuts through the sphere vertically. The rings option cuts through it horizontally. These diagrams might explain it better:

Segments go vertically

Rings go horizontally

Put the two together...

The default is for both to be 32, but, if you want more tiles increase the value and if you want less decrease it. Once you’ve chosen press ok and your sphere should be on screen.

UVsphere

You can reposition, rotate or scale your sphere if needed. To reposition it, with the sphere selected (right-click it if it isn’t selected) press the G key. This grabs the object that’s selected and allows you to move it freely. Try moving your mouse about. This can be useful, but we’re working in a 3D environment which…er.. has three dimensions that you can move along. To move it along a set axis you can either left-click the arrows coming out from the sphere or, after pressing the G key, press the key that corresponds to the axis that you want to move it along. For example, if I wanted to move the sphere along the X axis (the red line) I’d press the G key, the the X key. Now, no matter how I move the mouse the movements of the sphere are contsrained to the X axis.

Similarly, to rotate the sphere press the R key and to scale it press the S key. The same rules about constraining it to a certain axis can still apply.

You can do things such as repositioning the camera other such trickery but for that you’ll need to learn more about Blender for that.

With your sphere now ready go to Render (at the top of the screen) and then press VRM.

The VRM options window

I left the options as they are, but if you feel adventurous have a mess around. When you’re ready press the Render button and then choose the place on your computer to save it and what name to give it and finally press Save SVG. You’ll notice the egg timer appears in place of your mouse cursor to let you know that something’s happening but otherwise there’s a handy progress bar at the top of the screen.

Open up the saved object in Inkscape and voila!

It's an SVG Sphere!

That’s the first part of this tutorial done! The next part draws upon some of my own experiments but is also taken from the original tutorial.

When you’ve opened up the sphere you’ll notice that it’s all one object. This is because all of the paths (the tiles) are grouped into one. You can ungroup it if you want but for this tutorial you don’t need to. Give your object a base a fill and stroke colour. You can do this using either the colour palette at the bottom of the screen or the Fill and Stroke dialogue (Object > Fill and Stroke or Ctrl + Shift + F).

Applying fill and stroke colour

The final step of this tutorial from me is the following. With the base colour selected we’re now going to randomise the colours but within that hue. To do this we’re going to use the randomise filter which is located in (in Inkscape 0.47) Extensions > Color > Randomise.

Leave the Hue option unchecked (unless you want a multicoloured sphere) and then press Apply.

Your finished disco ball!

There is of course more that you can do to make this disco ball look more realistic but take a look at the tutorial that inspired this one and come up with something of your own

Click to download the SVG

Filed under Tutorials| Tagged 3d, Art, ball, Blender, disco ball, floss, Graphics, Inkscape, linux, osart, practice, Scalable Vector Graphics, SVG, vector | 1 Comment

Starting off Simple

10Sep09

I’ve been doing quite a bit of messing around with Alchemy. Whilst in search of solution for a problem in Blender I came across a rather awesome time-lapse digital painting from an upcoming Blender Foundation project, Durian. Not only was I blown away by the skill of the artist but also by the software that he uses. I’m an open source nut so was really glad to see him use GIMP and other open source software to produce his piece. One particular piece of software that stood out to me was Alchemy.

If you’ve watched the video already you’ll have seen how he used that program to create chaos from which to build something else from. I was a bit skeptical at first, thinking that GIMP and Inkscape can do this already and with many more options. However, upon using it I could soon see the benefits of using this program. As the website so clearly states, it’s not meant for finished pieces (although some have used it to create finished pieces). It’s meant to help generate ideas, to sketch, to just go crazy on!

After just a week of using it this was some of the work that I had created in it

I soon began to think more about what I perceived to be the point of the program. Typically, when I sketch my marks start off very light and whispy. Then, I draw over these whispy lines with more confidence until the original marks either become thicker and darker or are simply overshadowed by the newer marks. With practice you would then expect one to be more confident with their mark making, to the point where there are no more whispy lines, just sharp, clear marks.

Also, after many hours of studying you would expect one to make marks that represent any form in as few marks as possible. One important lesson I learnt at university is that you should only add detail where it’s needed. Spending 100 hours on an art piece may be personally satisfying but when people wont notice or have the time to appreciate that amount of detail why bother. In another situation, when you have a deadline looming, do you really have the time to add insane amounts of detail?

In time I feel I should be using this program to help develop this skill and my confidence as an artist. Drawing intricate layered pieces may look impressive but personally I know part of the reason I use that style is lack of confidence. I have put a suggestion to the developers to add a feature to Alchemy (and I’m slowing learning Java) that can help facilitate this by restricting the amount of shapes you can have on screen, but until then I’ve been doing a few tests of my own. Partly born out of frustration I’ve been trying to do portraits of myself using as few shapes as possible, in this case four shapes. As there are soooo many different recognisable features about our own individual faces it would be quite a challenge to pick just four features or shapes.

Working from memory I drew these portraits last night.

On a side note the good thing about Alchemy is that it can record a snapshot of your drawing to a pdf at timed intervals. You can download a zip of all of the pdfs if you really wanna see how I did it.

Admittedly the first portrait probably has six shapes (open the pdf up in Inkscape to find out) but that was because I accidentally used a white shape on a white background. Alchemy has no undo function so I just painted over it in black.

I slept on it and came back with a few new ideas. Do you really need to draw someone’s head or hair? That depends on what their most recognisable features are. I am quite well known for my hair, but I proved last year that even without it people still knew who I was *shock*. So, maybe it’s not that important. As a test for yourself, try taking a portrait picture of yourself. Open that picture up in your favourite picture editor (I use GIMP (duh)) and apply the photocopy (or equivalent) filter. If needed erase the background until you have just your facial features.

With Hair and clothes

Without Hair and clothes

Is it still recognisable?

So, I tried again to draw myself using only four shapes, but this time only my facial features. Here are my results (same four-shape rule applies).

New Portrait 1
(download zip of pdfs)

A little more recognisable? Four shapes might be a little bit too restrictive but you only really learn from challenging yourself. Why not try making the cursor invisble when you draw (press H) or draw “blind” (Affect > Draw Blind). Going back to the aims of the program once you feel more comfortable using very few shapes let yourself go a little bit and maybe use 10 or twenty shapes. Here is my final piece, starting with simple shapes, then going over with more detail

Final Portrait
(download pdf)

Filed under Tutorials| Tagged alchemy, Art, Blender Foundation, drawing, FAQs Help and Tutorials, gimp, graphic, Image editing, Inkscape, open, Open Source, osart, portraits, sketch | No Comments

Bending a penguin

08Sep09

Awhile back I did a quick vector illustration of a penguin. It was nothing much really but as far as penguins go I quite liked this one. Recently (as in, the last four months) I’ve been interested in databending. Have you ever had an image you’ve taken come out like it’s been through a shredder? That’s the effect that most databenders are after. In a way it’s like trying to reproduce an error. Once you’ve done it a few times you get to learn what effects different methods can produce but even then it’s very unpredictable. For a short tutorial on databending an image, take a look at the one I wrote for fizzPOP.

My curiosity lead me to see what can be done to databend an SVG file. In a similar way to a jpg or gif they’re just data but the difference is it’s human-readable. That is, someone could look at how an SVG is created and understand it. For example this code:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!-- Created with Inkscape (http://www.inkscape.org/) -->

<svg
xmlns:svg="http://www.w3.org/2000/svg"
xmlns="http://www.w3.org/2000/svg"
version="1.1"
width="169.71428"
height="169.71428"
id="svg2">
<defs
id="defs4" />
<g
transform="translate(-338.00001,-316.07648)"
id="layer1">
<path
d="m 505.71429,400.93362 a 82.85714,82.85714 0 1 1 -165.71428,0 82.85714,82.85714 0 1 1 165.71428,0 z"
id="path2816"
style="fill:#a02c2c;fill-opacity:1;stroke:#00ff00;stroke-width:4;stroke-miterlimit:4;stroke-dasharray:none" />
</g>
</svg>

..Produces this circle:

Vector Circle

With a bit of time you could easily read and write that code yourself.

So, with that in mind, using similar methods to this databending tutorial, can we apply a similar effect to the penguin? Like jpg’s etc the SVG has a header that, if modified, completely destroys the file. Using the above example the header is from lines 01 to 10. Open up your SVG in a text editor (for Windows I recommend Notepadd++, for Ubuntu/Linux Scite), cut those lines (a simple Ctrl+X will do) and then begin to edit your document!

You’ll notice that you have little flexibility with how you can modify it. With a jpg you can replace or delete any character and replace it with (almost) any other one. In an SVG if you change any of the letters then you render it useless. For example, fill is a function that defines the colour of a shape. If you changed each instance of fill to say fail it would just simply break the file. Epic Fail. What you want to do is replace numbers with other numbers. There is a danger that replacing #090909 with #0909999909 could break the colour values but so far I have encountered no problems.

Once you have replaced a few numbers paste back in the header and then save it again. Open it back up and take a look at the results! Below are a few modifications I made. The process is described in the link.

You may find that each shap has become very warped or that the dimensions of your document have increased tenfold! That’s the beauty of the randomness that is databending.