Thursday, June 8, 2023

Back To Reality: Camera Distortion and Other Conundrums



Some years ago, I wrote Mapping Out Success: Equine Topography that detailed a basic proportional method I use for my work. And for the most part, I still use it. Everything is based off the head measurement, making this method fast, easy, and adaptable. Even so, I’ve made some revisions over the years that are worth noting which I've since detailed in Measuring Proportion: Ahead Of The Game. But now let’s talk about something we all do…let’s talk about working from reference photos.


Photos are often our primary means to glean the information we need for our sculptures and our paint jobs, especially if we don’t have access to real horses. But here’s the thing, if we don’t have real horse experience or information based on real field study, we may miss an important point: Photos present their own issues and we need to compensate for them. Such things as lens distortion, perspective, lighting, and lack of diversity all introduce distortion of some kind and unless we’re aware of it, we may inadvertently infuse those distortions into our work.


Lens Distortion


All cameras, to some degree, introduce lens distortion into the image. Also known as optical distortion, it essentially causes straight lines to become curved in the image. There are three basic types of lens distortion: barrel distortion, pincushion distortion, and fisheye distortion. Barrel distortion is most common in phone cameras and with wide angle lenses. Pincushion distortion tends to happen with telephoto lenses. Zoom lenses can exhibit both barrel (at the shortest focal length) to pincushion (at the longest focal length). On the other hand, super wide-angle lenses tend to have fisheye distortion. The better the lens though, the less distortion which is all the more reason to buy the best lenses you can afford. That said, those lenses that more fully compensate for distortion are expensive, so just keep that in mind. For instance, take a look at these images…


The longer shadow line is the adjusted correction.

The longer shadow line is the adjusted correction.

The wider shadow line is the adjusted correction.

Images courtesy Maria Hjerppe

Note: Maria used a Canon L lens which is their (very) high end range lens. Yet notice how even with such a spendy lens we still have distortion? A lower range lens will have even more distortion.


Those are the same images overlaid onto each other, one unadjusted and the overlaid one adjusted and made more transparent so you can see the difference. It's subtle, but there. The discrepancy would actually make more of a difference for more precise things like the placement of facial features on the head or the length of the cannons, for example, where just that little bit can really mean a lot.


(It should be noted here that if you're taking your own photos, you can apply lens correction in many photo editing programs and apps. Look for it in the program you use. However, it's important not to apply this to photos you haven't taken as you don't know what sort of correction has already been applied and you risk over-correcting.)


So the trick here is being able to recognize these distortions and to also fully understand the technical nature of the lenses you use when taking your photos. It’s also important to stay within the frame center, the center of the focusing field, when taking any shot not only to minimize distortion but to set up a standard protocol for consistent images. Here’s the thing, the smaller the focal length (the wider the angle), the more distortion will happen at the edge of the frame, generally speaking. This is called volumetric anamorphosis and it essentially means that the further away from the frame center we are, the more stretched in perspective and the more bent in lens distortion the subject will become. 


To dampen all this, know the capabilities of your lens, take the photo well back from the subject, and keep the subject perfectly centered in the frame, vertically and horizontally. (This also happens to be good advice when taking shots of sculptures for your portfolio.)


Perspective


There are four primary ways perspective distortion happens. First is the distance between the subject and the camera. Cameras don’t have doubled-up vision or, in other words, they don't have depth perception so they see the world in a very flat way. They don’t compensate for perspective like our brains do. When it comes to angle shots then, the fore parts will be enlarged as compared to the rear parts, often markedly so. Indeed, the closer the camera is to the subject at an angle, the more pronounced this effect. We’ve all seen the typical nose shot that makes the schnoz appear extra large, for instance. And phone cameras are especially prone to this effect so be careful using their images for references. Second is the angle between the subject and the camera, or the horizontal or vertical rotation of the lens around the subject. Here again we see enlargement or distortion of those parts closest to the lens and when we involve an angle, this can create an elongation effect and even alter the angulation of things, something serious to consider when designing conformation or the orientation of patterns. Third is the distance between the lens and the ground which has that same effect. This can make body parts appear longer or shorter than they really are, another important consideration when constructing conformation and patterns. And fourth, the camera’s focal length plays a big part in perspective distortion so know exactly what your lens is capable of capturing at what distances. 


But all this is why having field study measurements and real horse experience can be so important to guide our adjustments back to reality. All in all, ideal perspective shots have been taken at a distance to help mediate that magnifying effect and knowing how to compensate back down to normal proportions through experience is a plus, too.


Lighting


The quality, intensity, and angle of the incoming light is a powerful effect in our photos. It can skew colors well away from their actual tone or it can obscure anatomical features outright, for example. Being able to adjust lighting in a photo editing program then becomes especially important if we want to reveal as much detail, surface features, and true-to-life qualities we need. In fact, we can use the Levels or Exposure adjustments in Photoshop, for instance, to lighten a dark photo to expose more detail or anatomical contours. Likewise, the Color Balance toggle will become critical to use for color compensation for paintwork. One thing to keep in mind though, a dark photo can be more saturated in color even when we lighten it which can skew color away from reality. To mediate this, de-saturating the lightened photo a wee bit can often better reveal its truer intensity. On that note, some promotional photos have jacked up the saturation levels to intensify the color of their horse for more eye appeal, so keep that in mind as well. 


Now when it comes to reference photos, finding images that have directional lighting is ideal because that angle helps anatomical features pop out. (White grey or double-dilute colors are particularly ideal here, too.) It can also reveal surface textures much better, a great boon for sculpture. Not ideal is a photo taken with strong shadows or even an overcast day because the former can obscure features while the latter flattens the lighting and so doesn’t reveal as much information as we’d might need. Even so, overcast days can be really useful for pattern translation as it avoids the harsh shadows that can obscure or confuse the track of a pattern. Worst though is a “blown out” photo in which the lighting is too bright because the exposure setting wasn't correct. This situation destroys a “blown out” area’s information completely since there’s just no way to adjust lost information back into a blown out photo, unfortunately.


Diversity


It’s smart to have multiple images of the same body part at the same angle in the same motion between many different individuals and moments in order to pick out what’s consistent and what’s different. Or with horse color, amassing multiple images of the same color, pattern, or effect. Indeed, it’s in comparing the differences and similarities that we start to pick out those things that are nonnegotiable and which things are options, even curious oddities. This helps our portfolio stay fresh and innovative rather than falling into habit and formula, two things which can be handy at times, but which tend to more often get us plateaued in our development. But if we strive to make each of our paint jobs or sculptures a bit different with all those options, we not only learn a lot of cool stuff along the way, but our process becomes a lot more fun and interesting to boot. Just as much, though, doing all this comparing also trains us to develop a deeper mental library which helps when compensating for lens and perspective distortions. Simply put, having more data in our heads just gives us more to play with and that spells more accurate work, more detailed work, more interesting work, and work that’s a lot more fun to paint or sculpt.


There’s this, too: Not everything we see in a photo or in a moment or an individual would actually translate attractively into a paintjob or sculpture. Sometimes we have to edit our work for the sake of the final impression. Like some areas may have so little detail they’d be boring and so we need to inject some to liven up the clay or pigment. Or perhaps a color patch on a sculpture does nothing to flatter it so we have to tweak it to marry better. We may also be familiar with the weird distorted limbs on race horses during photo finishes. The limbs aren’t actually distorting like that, it’s the limitations of the camera’s mechanics that are causing those goofy contortions. Add it all up then, it’s having a deep mental library born of comparisons from a diverse collection of reference photos that helps us in this department.


The Takeaway


So what’s the big takeaway from all this? Well, that photos aren’t gospel, they’re guides. Even the very best ones are suspect to some degree, and be particularly careful when using close up images. What's more, some professional photographers actually stage their subject and use a lens that accentuates certain desirable features to help along the final result. Hey, when you have to cater to the expectations of the owners, things get murky. Also actively try to compare different images taken at different distances if only to program your brain for identifying distortion better. We also need to supplement our references with a developed mental library born of practical experience. It’s not enough to simply copy something from a reference photo as close as we can. Instead, we need some interpretive powers to translate what a fallible camera with technical quirks is interpreting into a flat format. Maybe in the future, cameras will have AI to make those compensations our brains do so well, but until then, we have to mediate these factors with our knowledge base and awareness. Meanwhile, we don’t have to be duped by our photos into inadvertent misinterpretations. We can steer our proportional measurements back to reality with a bit of know-how and resourcefulness! 


Reality leaves a lot to the imagination.

— John Lennon



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