Books on the subject of lenticular imaging are few and far between. If your fascination with the subject is as keen as ours, we think you'll enjoy this very short excerpt, (minus the illustrations) from the most comprehensive book on the subject that we have ever read. 

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"3D AND ANIMATED

LENTICULAR PHOTOGRAPHY

Between Utopia and Entertainment"

by Kim Timby

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published in 2015

ISBN 978-3-11-041306-9

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MAURICE BONNET'S NEW VISION

Maurice Bonnet (1907-1994) was the French inventor who took 3D line-screen photography the furthest. He was the only one to commercialize it in any significant way in his country. Coming from a family of professional studio photographers, he started working on the subject in the mid-1920s, patenting his first 3D camera (now lost) in 1934. In 1937, to market his inventions, he founded a company named La Relièphographie - associating the words relief (for 3D) and photographic (photography). In the space of a decade, La Relièphographie would rise to fame in the world of autostereo-scopic photography, its images providing a striking illusion of depth approaching more closely  than ever before Lippmann's ideal of a view from a window.

Fifteen or so La Relièphographie line-screen photographs are known today, most made with a camera patented in 1937 that recorded thirty-three images. This device had a horizontal opening equipped with a row of thirty-three prisms facing the subject; the prisms directed light to thirty-three lenses, arranged in three rows of eleven above,  behind, and below them. The images were interlaced in the darkroom by placing the developed negatives back in the camera, then using it to project the images through a line screen onto a larger photo- graphic plate. The advantages of not using a line screen during the initial recording process were short exposure times (no screen filtered out light) and the possibility of enlarging photographs to different sizes from the same negatives.

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X-rays, aerial photography, and cryptography were also identified as possible uses of Bonnet's techniques, although no examples are known. Lastly, there are two very large photographs (60x50 cm) of unusual subjects, which could have been advertisements or images made by La Relièphographie to showcase its own technology. They picture an elegantly dressed couple and a man with a cow. People and animals could easily be photographed with the short exposure times of Bonnet's multi-lens camera and then enlarged - with spectacular results. Display devices accompanying the Alsa advertisement and the portrait also show La Relièphographie's attention to the practical issue of how clients could safely present and backlight their glass photo-
graphs.

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All of these thirty-three-image photographs give an excellent and immediate sensation of depth unlike any provided by two-image stereoscopy. Stereoviews could
easily give an impression of a series of superimposed planes that, in the words of one 1850s specialist, looked a lot like screens cut out and placed one behind the other. The effect was exacerbated if the images were recorded from widely spaced points to accentuate depth -a common but debated practice. In comparison, the depth of Bonnet's photographs was smooth from the foreground to the background. The illusion of depth wasn't just about things being in front of or behind each other: individual objects now appeared to be rounded and to have natural volume. This effect resulted from the number of images recorded and from their close spacing: Bonnet's thirty-three-image camera used a single row of prisms to direct individual images to adjacent lenses because this allowed him to obtain viewpoints packed more closely together than was possible when assembling lenses in a single row. One of Bonnet's colleagues observed that this 1937 camera provided a much smoother illusion of being able to move in front of the subject than Bonnet's first camera, which had only eleven or twelve lenses and wider spacing. Bonnet also understood the importance of
image format, criticizing the smaller views of other inventors for giving the impression of showing miniatures. 

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The camera wasn't everything, however. La Relièphographie also chose subjects with interesting volumes and details, arranging them within the frame to accentuate depth and engage the viewer. The advertisement for Alsa is an accomplished example: it renders a deep space encompassing both the model's headdress and the cake held out in the foreground; in addition, the package of baking powder is held up in a way that provides a satisfying detail behind which we can peek when exploring
modifications in perspective. In other photographs, subjects were oriented obliquely to make depth and perspective changes more evident. For example, the couple in
figure 43 was posed in a way that filled the depth of the represented space while leaving salient details visible to pull the viewer's gaze into the image. The way the couple's hands meet creates attractive forms in the foreground; the illusion of natural volume is continuous into the back of the image, where the woman holds her coat to her shoulder. Oblique angles were also used to strong effect in a pair of advertisements
for knit undergarments by Petit Bateau. In one, a boy in his undershirt was posed with a model boat (the brand name translates as "little boat") so that they formed a
V opening toward the spectator. Boy and boat were placed in a fold of a pleated accordion-like background-a form we naturally perceive in volume even when it is
drawn in simple perspective on a page. Here, the angles of the backdrops shaded folds and of the boy and the boat make changes in perspective very apparent as we
move. Another Petit Bateau advertisement pictures a woman holding up an under-garment and a young girl pointing at it. The girl was posed almost perpendicularly to the picture plane, in a way that reinforces the impression of her physical presence by making her chest more visible from some angles and her back from others. At the same time, the undergarment was held parallel to the picture plane, creating a stable anchor at the center of the depicted space with respect to which the other elements change places as we move. In everyday life, motion parallax - or the
fact that closer objects appear to change places faster than distant ones  - is an important indicator of depth perception. Bonnet's 3D photographs not only allow the viewer to move, as Lippmann imagined, but also use the effects of motion parallax to heighten the illusion of depth and volume.
 

The visual role of the centrally placed garment in figure 45 underlines another one of La Relièphographie's compositional tools: the photographer carefully defined the apparent position of the 3D subject with respect to the physical surface of the photograph, making certain elements appear to be in front of the window formed by the edges of the picture. This was already the case with the photographs of Ives and Estanave, but it is particularly impressive when associated with the profound illusion of depth and the large formats of La Relièphographie's creations. In figure 45, the undergarment appears to be situated at the surface of the image; the woman's fingers and the girl's shoulder, arm, and curly hair appear to come out in front of it; and other
elements are situated behind it. In figure 44, the glass surface of the image corresponds to the boy's eyes, with his shoulder and the bow of the boat coming forward. It is even possible to reach one's hand into the part of the scene that appears to be in front of the glass. The total space represented appears to be at least 40 or 50 cm deep, and the elements situated behind the image surface have just as much volume as those in front of it.

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The naturalism of La Relièphographie's photographs is closely tied to being able to move and see changes in perspective. The effect encourages us to determine just how far we can turn around the subject. In doing so, sudden "hiccups" in the image
inevitably appear at regular intervals, corresponding to when we simultaneously perceive the end and the beginning of the series of thirty-three images recorded. If
we move progressively in front of the photograph from a position far on the right over to the left, for example, the subject is visible a little from one side then gradually
from the other - then suddenly from the first side again, with the sequence repeating several times until our angle of vision through the screen is too oblique to correctly perceive the interlaced images. We are in front of what might appear to be a window
onto reality to use Lippmann's analogy, but this window has its own particular rules, as defined by Bonnet's camera system and screen. Although the "hiccups" in
the image are noticeable, it is hard to believe that what we see doesn't perfectly correspond to the natural view we would have of the subject. The illusion is so real that even though no vertical parallax information is recorded, our brain creates a slight impression of perspective change if we move up and down - literally not accepting
that we aren't in front of a solid object.

Michel Frizot describes the illusion of 3D photography (whatever the process used) as always being dual, made up of photography on the one hand and an illusion of space on the other. Although stereoscopic illusions can exist separately from photography, in their photographic form, he argues, attention is focused "squarely on the admirable naturalistic testimony of photography" instead of on "the artificiality of the instrumental preparations necessary."  Photography and the illusion of depth had never before been so seamlessly intertwined as in Bonnet's line-screen images. Their perceptual realism is so convincing that even its visible flaws work to the photograph's advantage when it comes to engaging the viewer. Michael Leja's analysis of the appeal of the trompe l'oeil paintings of William Harnett for early twentieth-century viewers demonstrates a similarly satisfying cocktail of flawless representation and details that "undermine the illusionism of the image." In these paintings, strategies including a palpable seeming rendition of texture and the presence of objects showing the luster of handling provoked  "a desire for tactile gratification," inciting viewers to literally reach out and touch the image. Similarly, the illusionistic space of Bonnet's photographs tempts one to physically locate the perceived image. In the trompe l'oeil paintings, bits of impasto, or thicker paint, made the "materiality" of the creation "erupt" in certain spots. For Leja, these interruptions didn't break the power of the image; on the contrary, they focused the viewer's attention on "entry points" into it, eliciting a desire to "pry open" the represented space. Likewise, the "hiccups" in Bonnet's photographs heighten the apparent perfection of the image as seen from unmarred perspectives while constituting a concrete break in the illusion through which we can start to mentally grasp what the photograph does and doesn't render. Exploring the mediated depth of these line-screen photographs is more seductive than looking at actual objects.

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"The eye isn't used to this new vision," proclaimed Maurice Bonnet in 1936. Such an attractive and easily viewed 3D illusion was essential to commercializing
autostereoscopic photography. Because the process was now capable of immediately
commanding the attention of unsuspecting passers-by, La Relièphographie could promote it as an advertising medium (indeed, it recommended placing its photographs in shop windows, at eye level). Bonnet devised an intelligent marketing strategy based on control of the delicate aspects of image production by his company. His photographs also struck a seemingly ideal balance between the number of images
interlaced for impressive 3D and the darkening of the photograph entailed by the widening of the line screen's opaque zones. The inventor wasn't satisfied, however. He judged his line-screen photographs too dark and fragile to be really commercially
successful, and wanted to free them from cumbersome light boxes. The only thing that would allow these changes had also been described by Lippmann in 1908: a
screen composed not of lines but of lenses.

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                 exerpted from:

"3D and Animated Lenticular Photography: Between Utopia and Entertainment" is a profusely illustrated and engaging interdisciplinary study of a wide ranging body of images that have captivated viewers for generations.

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