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Seifer's Multimedia Series #2

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Posted 29 August 2004 - 06:52 PM

Seifer’s multimedia tutorial series – Texture making in Photoshop

This is another in my series of tutorials that are aimed towards creative thinking. A little bit of theory is needed before we jump into the actual tutorial itself.

Now, many people passing through the forums know what a pixel is, or at least, they know enough to get by. However, pixel is actually an acronym for ‘picture element.’ Its clusters of these pixels that create patterns and these patterns form pictures and art. Now, it’s likely that many people don’t think about the pixel breakdown of what they look at but sometimes it can help. If we are able to understand what happens at a pixel level when we do what we do, we open up a greater range of possibilities and creative solutions to problems you might face.

Visual perception also comes into play here as when we look at a piece of art, we are actually looking at an illusion of sorts as a basic premise of art is that the mind can be tricked into seeing familiar shapes if the artist does their job well. The Sistine Chapel painted by Michelangelo is a very good example of this as details that look like they can be attributed to the architectural structure are actually painted by Michelangelo. So, what we are seeing isn’t the ‘actual’ but the ‘contrived’, perception that is altered by the filters of our own experience.

Now, what we’re going to do for this tutorial is to make an organic texture, some tree bark. It might not seem all that common to Infinity Engine modding but I’ve picked it as we can look at how we can manipulate pixels into a desired form through manipulation. As we all know what bark looks like (or I hope we all do) we can look at the constructive theory more then the visual details of the image.

Section One – Getting started

Bark generally has a vertical grain and this is what we need to try and get out of our pixels. Now, first of all, start with a new document 360px by 360px on a white background. We need a white background as we will be adding noise later on.

Once you have this, use the rectangular marquee tool and draw a sliver at the top of the document. Next, add the noise filter with an amount of 30. Also make that you’ve added monochromatic and uniform. You should have something that looks like the image below.
Posted Image
Now, what this essentially is, is a random pixels sized from a single pixel up to larger groups. If you zoom in, consider what will happen if we scale that noise filter vertically from top to bottom.

This is what we’re going to do next. Using the transform tool on the sliver of noise (alt-ctrl-T for PC, alt-cmd-T for Mac) and drag it down to the bottom of the document. You should have something that looks like image two, below.
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Now, consider what we have here. All we have is a set of vertical black and white lines. This has happened as PS hasn’t interpolated the pixels for the stretch yet but it has stretched them for the preview. Interpolation will occur when you apply the transformation. Do this now by double clicking in the window. This will apply the transformation. Looks a little like Christmas tinsel. This is our first illusion. Look at this example.
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Section Two – What have we got here?

Now we need to stop for a moment and look at what’s happened so far. You might be asking where did the tinsel come from. Well, the answer to that lies in the pattern of the noise we stretched and in the manner which PS solved the stretch though bilinear interpolation and aliasing. If we had used a different type of pixel source such as a motion blur, the result would have been very different. Later on, I’ll try and show you a few different effects on how different sources might lead to different results. However, we need to get back to our tree bark first.

So, at the moment we have random vertically aligned streaked patterns that we’ll need to soften up. What I’m hoping you’ll see eventually is that, in greyscale, the vertical streaks we have aren’t far off from what the eye will perceive as the bark we’re looking to emulate.

Our next filter is going to be the Gaussian Blur, one that can be selected from the filter menu. Make sure that the preview box is checked and slowly increase the value slider from its lowest value and look what happens in the document window. Look at the example below for an actual example.
Posted Image

When we do this, the tinsel strands soften up and spread out a little more, they start to look like they could perhaps take us to where we want to go. Why is this I hear you ask? Well, consider what bark actually looks like aside from the inherent vertical patterns it has. The darker areas are the crevices and the lighter areas are the upper crests and crevices. For the moment, set the value to 1.3 or a similar value and hit OK.

Take another look at the new texture. It’s too smooth and far too soft. What we need to do is add something that will look like tiny pores and detail. There are two possible things we can do here:-
1) Add both an additional noise filter as well as the sponge filter.
2) Use just one or the other.

This factor will depend entirely on what you want to replicate, as this method can also be used to replicate a rock texture. We are going to use both with the noise filter being used to create the pores and the roughness whilst the sponge filter can be geared to suggest moss, mould growth and divots.

First of all add a little more noise with the same setting as before, uniform/monochromatic set to 30. Now, at first this will be too much. What we can do here is to correct it with the fade command. Some of you might be asking why we didn’t simply apply less noise rather then fiddling around with the Fade options. The answer is simple. Here, we can call on another one of PS’s internal algorithms to not just remove the degree of noise added but to combine the before and after states through what we call an application mode.

Posted Image

Take a look at the screenshot above. See that drop down box in the fade dialogue box. That’s where we can access the application modes and they are the same type of modes that are seen in the layers, brush palettes and so on. What you should be doing is using the preview box to help what determine is the best effect to use. My own settings were a fade of 80% with the multiply mode selected.

It’s looking better but still not complex enough. Now we are going to stretch the contents of the document NOT the entire document or the canvas though. Use the transform tool to stretch the contents by 50-100%. This will stretch the noise you just added by adding more levels of vertical grain.

Posted Image

Now, repeat the previous step of adding more noise, which will add back the ‘pores’ we just stretched.

Now that’s been done, our next step is to toy around with the sponge filter. Select this filter via the Filter -> artistic submenu. We don’t want to add too much here as the sponge filter is much stronger then simply adding noise and is therefore much harder to ‘dial-out’ via the fade command. I used the following settings: -
Brush Size 1
Definition 3
Smoothness 2

Posted Image

Once again, use the fade command, using multiply from the application mode drop-down box and set the slider to approx. 50%. See the screen shot below for an illustration.

Screen shot 08

Section Three – Sleight of Hand
Recap thus far, we’ve laid down the basic pixels, distorted them, modified them and now we stand a few steps away from the final key strokes. However, there are a few things preventing the illustration of wood presenting itself to the eye at the moment. One of them, obviously being colour, but that is an element we all almost dead last. Take another look at what we have so far; we have soft elements and sharp elements. Whilst bark does have both of these characteristics the sharper elements need softening first.

Use a Gaussian blur and apply a small amount of radius, I used approx 1.0. What we want to do here is just to soften the image a little and help to blend the sponge filter effects into what we did with the first few steps. See the example below for this.

Screen shot 09

What we might do now is to tighten up some of the edge transitions. From the filter menu, chose unsharp mask. Apply roughly 200%. This is a high amount but will be tempered by the following settings:-
Radius – 1.2
Threshold – 3

Screen shot 10

What these settings instruct PS to do is to be more selective about where the sharpening effect is applied, which in this case, are he areas of higher contrast, areas that we will perceive as edges. The next step is adding colour. There are several manners of doing this in PS but our method for today is via the hue/saturation dialogue.

Since we already said we were looking at an oak/redwood effect, we’ll want a deep brown without too much saturation. Not many things in nature are saturated with colour. Bring up the hue/saturation menu via Cmd/ctrl-Alt-U and set the following:-
Hue: 20
Saturation: 20
Threshold: -30

Screen shot 11
We could leave it at that but another tweak that might b worth looking at is the curves panel (ctrl-m) where you can tweak the RGB values.

And that’s it. With a fresh eye, I hope you’ll agree that it can pass for a hunk of bark. Don’t be overly critical as the aim of the tutorial wasn’t to show you how to make a photo-realistic texture but to highlight that pixel's are the clay-stiff of digital art, which does include Infinity Engine area making and all its textures.

Toy around with different filters and see what you get =). Have fun.


Edited by Seifer, 29 August 2004 - 06:58 PM.

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