Gaussian Blur

On another blog, I wrote a post about Gaussian blur and what it actually means. This is a pretty widely used function in Photoshop, so I thought it would be useful to describe what's actually going on at the pixel level. Rather than repeat all this, I'll just include the link:

http://technologyforartists.blogspot.com/2008/07/gaussian-blur.html

That other blog, by the way, was sort of a precursor to this one, so I may refer to it from time to time, but more often, I'll rewrite and repost any good stuff here.

More on Images and Signals

In Images as Signals, I tried to show how an image like this:

could be thought of as a signal of lightness ... a measure of how light each pixel is. I also drew a graph like this:


of that signal. Each of the ramps in that graph is one horizontal row of pixels, read from left to right (darker to lighter). So if you think about two pixels next to each other on the same row, their lightness measurements on the signal might be like this:

In other words, the pixel to the left, which is slightly darker, occurs in the signal just before the slightly lighter pixel to the right of it.

If, on the other hand, we want to locate two pixels, one above the other, with the same lightness, their positions on the signal might look like this:

What To Talk About

A while ago, I was thinking of writing a book on technology for artists. I was going to try to describe, in artist's terms, how the underlying technology of things like Photoshop, Premier, etc. work. It wasn't going to be a "How to ..." book. There are already plenty of those. It was intended as more of a general course in technology to give a basic understanding that would help in using any hardware or software.

This discussion is more general. I'm hoping it's not just for artists, but for anyone interested in how art and technology play together. I'll be happy to share what I know about the engineering side of digital art tools, but I'm also hoping to present my ideas about some broader topics like aesthetics, art as signals, etc. Most of all, I'd love to hear some comments and questions back, so I can learn some new ideas.

Some of the things I was going to include in that book:

1. Basic math (in non-mathematical terms!!) for understanding digital images, video, audio, etc.
2. How digital images work
   
1. Raster images
2. Vector images
3. Color theory
4. Typography
5. Printing
6. Video
   
• Animation
7. Audio
8. Technology tools for learning about and understanding art
   
9. Technology as inspiration ... art that's about technology

Sound interesting? Anything else we should talk about?

Impending Name Change

This is just a head's up that we'll be changing our name soon. I had wanted something to convey the idea of the convergence of art and technology, and Art Tech Fusion (www.arttechfusion.com) seems to do that. I apologize in advance for any delays while various DNS servers figure out what's going on.

Images As Signals

I want to explore this idea of signals and signal processing in relation to art. Wikipedia offers this definition of signal in the context of electrical engineering:

In the physical world, any quantity measurable through time or over space can be taken as a signal.

Photoshop, for example, is filled with code that uses signal processing techniques to process images. Filters, blur, sharpening, edge enhancement, etc. all come from signal processing.

To understand this a little better, remember that a digital image is basically a grid of picture elements, or pixels, arranged in rows and columns. For example, consider this image:


If we zoom in on Cindy's (the gray cat's) right eye, it looks like this:

Each of those colored squares is one pixel. If we consider each pixel, one row at a time, starting from the upper left corner, we get a sequence of values. There's the upper left pixel, then the one to the right of that, then the one to the right of that one, etc. until we get to the upper right pixel. Then we move down one row and consider the one just under the upper left, then right, etc.

If the image were 10 pixels wide, the order in which we'd consider the pixels is given by these numbers:


In this way, the whole image can be thought of as a sequence of numbers, each representing a pixel value. That's a signal.

Consider an image that has alternating black and white vertical stripes:

If we consider just one row of pixels in this image (indicated by the red box), we can think of the signal as a graph of how much light is given off by each pixel. So the graph of the signal for this row can be thought of as looking like this:

The graph is very low where the pixels are black, because almost no light is given off. It's very high for the white pixels, which are giving off the maximum level of light.

Let's consider another example:

Again, thinking of just the row highlighted in red, the graph of the signal for this looks like this:

The light value starts out very low, and gets gradually higher as we move toward the right edge of the image. But remember that when we get to the right end of the row, we move down a row and start again at the left, so the actual signal for this image looks more like this:

Of course, there are more than three rows. This pattern keeps repeating with one diagonal for each row of pixels.

Is this making sense so far? These are simple examples, but I think they illustrate how images can be thought of as signals (and, I suppose, how signals can be drawn as graphs, which are basically images.)

Art Signals

There's a great convergence of art and technology taking place. In a sense, it's been taking place since the beginning of human history. The mixing of paints, the making of musical instruments, and many aspects of performance have always involved technology. But the pace has quickened, and become almost frantic in recent decades.

The area of technology most widely connected with what we now consider digital art, be it graphics, animation, music, video, or other media, is what engineers call signal processing. Basically, all these art forms are represented as signals ... sequences of numbers. We'll talk more about that, but the most obvious interpretation of ArtSignals is the widespread use of technology ... of signal processing in art.

But, in another sense, technology not only enables some art forms. It inspires and directs them as well. Some art deals with technology as an explicit or implicit subject. A work created in Photoshop means something different from a similar looking work done with more traditional media. Even movies like Star Wars or WALL-E have important technology themes.

In addition, art plays a role in the creation of technology. The clearest example is the abundance of opportunities for visual designers and industrial designers in the creation of new high-tech products. In some sense, you can consider the difference between Apple and Microsoft as a difference in the priority each company gives to design.

Finally, art itself can be thought of as messages, although not always easy to interpret. Art works themselves are signals.

So,

1. Technology is used in the creation of art.
2. Art is used in the creation of technology.
3. Technology is often the subject, directly or indirectly, of art.
4. Signal processing, and perhaps other aspects of technology, can provide one avenue for interpreting art.
   

I think 1, 2 and 3 are pretty evident. Number 4 is going to take some more discussion.

So I want to use this space to talk about all these things about art and technology. I'm hoping we can keep it light and conversational, and still get into some interesting ideas. Even talking about signal processing, we stick to pictures and non-geeky language.

I've worked for many years in the creation of graphics and multimedia software for art, design, animation, and education. I'll be happy to share what I know, but there's so much more I want to learn. I'm hoping to learn from you.