Tag Archives | pattern outline

Dogs are different

Whippet1

I had noticed this about dogs many times in the past, and finally got the chance to snap a good example. One of the first things we stress to beginning horse artists is that the white patterns overlay the body color. The shading does not follow the outline of the spots. Pixel artists even have a name for this kind of artistic error, where the outer edges of a shape are dark and the center is light. It is called “pillow shading“.

Yet for some reason, sable shading in dogs often does exactly that; it concentrates along the edges of the colored patches. Notice the dark area along the topline of the Whippet above. Sable often does that, but look at how it travels down the edge of the two hindquarter spots. Just so it’s clear that the sable shading didn’t just happen to darken at the hip there, here is the other side of the same dog.

Whippet2

Here the white occurs a good distance forward, yet the same dark edging is visible on the border. Using Photoshop to remove the white patch and recreate the dark area underneath, it’s even more obvious that the dark area would be oddly placed were it not related to the white patterning.

Whippet2b

I have no idea why black shading behaves like this in dogs but not horses, but it does go to show that artists have to look for these kinds of details if they want to capture animal coloring accurately.

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Sabino influence – lacing the edges

The post from yesterday talked about the tendency of sabino to break dark areas of a pattern into smaller, more numerous pieces. The other thing that sabino tends to do is degrade the edges of the other pattern by making them lacey, roany or ragged.

Using the pattern from yesterday, here is an example of how that might look.

The tobiano pattern is still plainly visible, but the edges have become lacy and irregular.  Looking carefully, it’s obvious that this isn’t an overlay of a loud sabino pattern because the irregular areas are concentrated along the edge of what would be a tobiano pattern, instead of the areas associated with sabino.

Here is a horse with this type of sabino influence.

SabLace3

Notice that while he does have lacey markings along the girth – something you could expect on a sabino – the primary direction is upward toward the withers, following the line his tobiano pattern might take.  Meanwhile, there is almost no white under that front armpit or along the belly, which would be the most likely place to look for white on a purely sabino horse.  So the sabino instruction to “add lacey white” has been redirected to follow the pattern edges laid out by the tobiano gene.

And here is a more extreme version of lacing the edges.

SabLace4

The edges aren’t always lacy, though. Sometimes the edges take on more of a ragged, torn appearance. This horse is a good example of that.

RaggedEdges

(I apologize for the “headless horsewoman”. Since I am only taking pictures for my own reference, I often zoom in to get the horse big in the frame, which means a lop a lot of people off!)

Laced edges are something not only seen when sabino is paired with tobiano, but other patterns as well.  This horse is most likely carrying sabino and frame.

SabLace2

The softened, roany look to the marking on her side is very typical of sabino, yet all four legs are unmarked.  Although not as obvious in this picture, the marking did not extend under the belly either.  The appearance is that of a purely frame pattern with just the outline altered.

And here is a splash overo with laced edges. Notice how the sabino patterning follows the edge here, too.

SabLace1

I should caveat this post with one warning for painters, though. It is true that complex, ragged edges are associated with the presence of sabino and that horses without it have simpler patterns. The edges are more even, but it should be said that even on simple tobianos – and simple splash overos, the other “smooth” edged pattern – that the edges can still have irregularities. Here is a close-up of the brown tobiano mare from the previous post.

UnevenEdge

The overall impression is still that of a large, fairly even patch – but the up-close look will often show this kind of edge.  (I’ll talk about her roaning in a later post, because that’s not necessarily a sabino trait either!)

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Pattern interactions – overview


Slide from the 2002 BreyerFest presentation

A few years ago, when giving a presentation on horse color, I used the term “pattern hierarchy” to describe what happened when a horse inherited two or more patterns.  Often the genetic instructions from one pattern conflict with those of a second pattern.  For instance, the gene for the frame pattern dictates that the horse should have dark legs, while tobiano calls for white on all four legs.  In that situation, would the legs be white, dark or some combination of both?  Pattern hierarchy seemed to be a good term for the rules that governed which instructions took precedence.

In presenting things this way, I was trying to dispel the idea that white patterns are simply layered one on top of another.  It is easy enough for an artist, especially an artist painting a three-dimensional figurine, to approach white patterns in this way.  It is often how patterns are painted, with white added over the top of the body color.  I felt it was important that artists understand that while patterns can layer in this way, their relationships were not strictly additive.  Sometimes the genetic instructions not to add white in a given area had priority.  An extreme, mostly-white sabino that inherited the frame gene might have a dark topline, because the prohibition against white on the topline was stronger.

But my own observations tell me, and recent genetic studies certainly confirm, that the situation is a bit more complex.  What I called pattern hierarchy might more accurately be called pattern interaction.  It is true that sometimes that interaction boils down to a simple hierarchy; the white leg rule for tobianos pretty much overrules any instructions about leg color from the other patterns.  But sometimes one set does not take precedence, and instead the instructions for one pattern are subtly altered by another.

An Example

Of the various pattern combinations, tobiano paired with sabino is probably among the most common.  In fact, among American horses it can be pretty difficult to find tobianos who are not also carrying some form of sabino.  Most light breeds, and almost all New World breeds, carry sabino to some degree.   That makes it a good place to study the interaction of the two patterns because there are so many examples.

This is what tobiano typically looks like when no other patterns (or modifying factors) are present.

The face and chest are dark, as are the hindquarters.  The edges are smooth, and while they do not form perfect circles, they do suggest large, rounded shapes.  Notice also that there is no visible face white. In most breeds tobiano does not add white to the face, so without one of the patterns that does, the face will be solid or nearly so.

This is what sabino (or at least one of the more common forms of it!)  typically looks like when no other patterns are present.

Unlike tobiano, which has a pretty consistent look in its pure form, sabino has a wide range of expression.  Nonetheless, the blaze extending over the lips and chin, white on the belly, stockings that rise in the front of the leg and ragged edges are all typical for sabino.

Here is a tinted overlay of the two patterns.

Which, painted one on the top of the other, would result in a horse that looked like this.

Notice the conflicting instructions for the white on the closest hind leg.  The tobiano pattern has white traveling up the broad side of the upper leg, as is more typical for that pattern.  Sabino, meanwhile, has the white moving up the front edge of the leg.

If patterns behaved as simple overlays, this is how a combination of these two patterns should look.  And if patterns had a simple hierarchical relationship – if accurately portraying combinations was just about resolving conflicting instructions – all we would need to know is which version of that leg white might “win out”.  Does the white go to the front, or to the side?

The problem with this approach is that it assumes the two patterns remain discreet, separate from one another.  What actually happens is that sabino will subtly alter the original tobiano pattern.  Tobiano is still going to predominate, of course.  In the simpler, hierarchical view of pattern combinations, tobiano can be considered “king”.  Whatever else is inherited, horses with the tobiano gene almost always retain a strong suggestion of the pattern.  But the effect of the sabino gene will be visible. In the next few posts, I’ll talk about the different ways that sabino tends to interact with other patterns. This ties in with what was going on with the possible manchado discussed a few days ago, because the first interaction we’ll cover is the tendency of sabino to alter spot frequency.

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