Introduction

Skinning is all about creating an illusion; making a bunch of blank pixels on the surface of six rectangular prisms look like something else simply by adding color. Careful use of color can create the illusion of detail and three dimensionality. Beyond recognizing, and relating to, the character you are trying to portray in your skin design, features such as asymmetry, curvature, and gradients catch a viewer's eye and encourages him/her to interact with your posting. (There are several tutorials by PMCers on selecting palettes, hue shifting, and shading, so I won't go into those very important topics. Check the skinning forum for tutorials.)


Asymmetry


I'll start with asymmetry. By asymmetry I mean not having the right and left halves of a skin be mirror images of each other. You can't do anything about this with the arms and legs but you should definitely consider it when designing the head and body. Asymmetry is most powerful at the whole body part level but definitely has impact at the neighboring pixel level as well. My "Hummingbird" skin has a high degree of large scale symmetry on the head and body while my "Transplant" skin has no large scale symmetry on the body. The head of the "Transplant" skin is symmetrical in terms of the layout of the eyeball but the shading makes it asymmetrical and gives the illusion of a light source above and to the right of the skin. If you inspect the hummingbird image closely, you will notice that the pixels on either side of the center line are not exactly the same color. Those to the left are a tad darker than those on the right. This slight change creates the illusion of a light source to the right of the image and makes the image appear not to be flat.





Using a darker gradient away from the centerline of the "Hummingbird" creates the illusion of the body being more cylindrical even though it is still a "box". By playing with gradients, hue shifting, and shadows you create the illusion of many different shapes. My "Turkey" skin appears to have a fat tummy while my "Red Panda" appears to have more of a feminine hourglass shape.





One of my more recent stylistic choices is to try to make heads look more spherical. I tend to go against the convention of making the gradient darken all the way to the corners and instead use a light-dark-light gradient. Comparing the heads of my earlier Emperor "Penguin" skin to my newer "Adelie Penguin" skin illustrates what I am talking about. I use a similar approach when shading shoulders.





One of the odder things I have done with symmetry is to rotate the head of my "Parrot" skin 45 degrees. Most of the comments I received on my parrot dealt with either liking or not liking its unusual head.





One last thing on symmetry. Too much symmetry can spoil the impact of a skin. Look for skins with strong horizontal bands running across the body and even the arms and legs. These are common on skins that use shading templates. The viewer's eye fixates on the banding and not the overall image. Diddling the color of a few pixels here and there can mitigate this effect and increase the appeal of the skin.




Curvature Illusion


Another illusion technique that I employ is what I think of as curvature. The editing and static previewer tools skinners use get us in the habit of seeing skins as orthographic projections (straight on views from front, back, and side). This severely limits creativity in general and really limits what is done with arms and legs. Since arm and leg surfaces are only four pixels wide it is nearly impossible to create interesting details or get much in the way of a contrast gradient. I like to increase the amount of canvas I have to play with by working around corners and edges. I actually think this approach makes skin much more interesting to look at during game play because we usually see other players from odd angles and not directly from the front, back or side. Notice how the "Turkey" wing wraps around from the front to the side. Likewise, the upper leg of the "Red Panda" looks like a curvy thigh.





This approach leads to some design challenges. On the "Turkey" and "Hummingbird" skins, I had to create feet and tails on the front and back of the skin. This works out well when viewing the skins from any angle other directly side on since you can't see the front and back of a skin simultaneously. If you view these skins from the side they appear to be floating.





Sometimes things don't work out so well, like on my "Sunflower" skin - it has a stem on each side of the leg. Sometimes things work pretty well like the "Parrot" skin and my "Santa in the Saddle" skin where it looks good to have the reindeer's leg wrap around the corner.





The curvature illusion goes beyond working around corners, it extends to using color to create eye catching arcs that can span multiple body parts. "Kitty Softpaws" has a continuous curve (dashed red line) down her back that stretches from the top of her head all the way to the bottom of her feet. She also has a curve that wraps around her body when seen from an off-axis view. Notice that the intensity of the curve varies from heavy to faint which makes the curve seem more 3 dimensional and allows the eye to puzzle out the continuation through the fainter places. The spherical head illusion, mentioned before, really adds to the curvature illusion. Curves that branch into secondary curves and tertiary curves give the eye more paths to follow. The "Orca" skin (on the right) capitalizes on curves as well. One of the things I tried to incorporate into this skin was a symmetry between the top of the snout and the bottom of the lower jaw.





Gradients


Some viewers mistakenly believe that I am doing HD skinning because I go for smoothness and realism in my designs. The HD appearance is another illusion. By carefully blending colors in a gradient, it is possible to give the illusion of using pixels that don't exist. It may sound weird, but by picking intermediate shades, the eye is tricked into believing that the same pixel is two or more different shades - which it can interpret as more pixels. If you look at the area outlined in the "Hummingbird" skin, you will see some pixels that are intermediate between the surrounding green and the surrounding white. The eye interprets the pixel as partially green or partially white depending on whether you are focusing on the green body or white breast of the bird. Also notice the transition between green/white and red/white that occurs just below the shoulder. The two colors have about the same gray scale value where the transition occurs which makes the transition feel seamless. Looking at the closeup of the "Red Panda" arm, you can see a transition between red and black going on. By carefully working on the ratio of red to black in any pixel it is possible to make the eye think that a fairly smooth curve is present when the skin is viewed as a whole even though the pixels are quite jagged when viewed this close up.





A number of viewers have suggested that I move to making HD skins because they have more pixels and would allow me to create even more realistic skins. While that is somewhat true, I haven't made the move because the illusions I use would tend to breakdown at higher pixel count to box dimension ratios. In my opinion, HD skins don't look curvy, they look like pictures (highly detailed pictures) pasted onto boxes.


Concluding Thought


Now that I have explained some of the illusions that are possible, go out and look at your skins, and the work of other skinners, to see if you can spot the illusions being used either intentionally or unintentionally. Remember, knowing how an illusion works doesn't mean you are no longer susceptible to the magic it appears to create.