#402 - VIDEO/PHOTOS | The Pillow Demons

A video clip made hours ago at a residence in Santa Clara shows several pillow demons, all of which appear on the same corner of my pillow; and, just like the old maid and the young maiden in Chica o Vieja, the faces overlap each other. This enhanced still frame highlights the most prominent one:
A color-enhanced and sharpened still frame (enlarged x2), showing an apprehensive, beret-wearing pillow demon peers sideways out of a fearful eye, with his upper lip coiled in snare, bearing gritted teeth
There are at least four other faces overlapping the one shown above; however, unlike the aforementioned painting, in which each face has an equal presence (e.g., same size), you might have to do more than just change your focal point as you stare at the image to see the face of each pillow demon. Specifically, you may have to make adjustments to color, as well as other enhancements (such as sharpening), to images of pillow and blanket demons to visualize faces that are less prominent due to overlapping.
NOTE | To enhance your own images showing demonic activity (or other), see Enhancing photos of demons.
Such faces include ones that share most of the same features as the face overlapping it, or ones that have less definition (fewer features and/or less depth and shading) and/or less surface area (by facing profile, particularly when the overlapping face is facing front). Others may require the imposition of a border mask (as was used in the still frame above) to assist in defining the outer region of the face appears.
NOTE | For the typical post on blanket demons, I only highlight the demon with a face that appear to have a round dark dot in their eyes, where the iris/pupils should be.
This was incidentally discovered when I viewed the same still frame in two different versions of Quicktime. Specifically, in the still frame made from the video played by Quicktime Player 7, only the face shown above was apparent; however, in Quicktime Player X, which uses a blacker black and a whiter white (i.e., an extended gamma range), another face emerged:
The extended gamma range of Quicktime X over Quicktime 7 revealed another face
The video clip is my first one showing a demon blending its face with a pillow. Like their blanket demon cousins, a pillow demon creates a face by bending and folding the pillow's fabric, and otherwise shapes the topography of the pillow to create contrasts between light and shadow, which are necessary to add realistic depth to facial features; and patterns and stripes are used to define the borders of those facial features, outline the region of the face, and for eyebrows a:

This video was made at same Santa Clara residence where I acquired the video and photo showing a blue-tinted demon blending with light and a photo of the white mask of a female hobgoblin demon hovering over a human woman's face.

#401 - TECHNOLOGY | Enhancing photos of demons (and the like)

While looking for ways to clean up crappy photos of my boogey men, I came across a GIMP tutorial entitled The High Pass Filter for Radical Sharpening, which had easy-to-follow instructions for improving the quality of images that are blurred by the motion of the camera.

Here's a before and after of my first attempt, in which you can see nearly twice as many features in the demon's face in the improved version as you can in the original:

EnhancedOriginal
Here's the result of applying the same method to another image, from which I learned that images that are motion-blurry benefit the most from this method:
BeforeAfter
I enhanced another image, this time, one that is very grainy and unfocused; it would have benefitted most by applying sharpening to individual parts of the face, as multiple renderings revealed thatsome settings work better on one part, while not so good on the other:
BeforeAfter
Here's another image, which is highly contrasted; like, motion blurs, that seems to be an ideal condition, as well:
BeforeAfter
This image lacked contrast, which makes it difficult to sharpen because edges are defined by significant contrasts in color, and it is the areas created by these edges to which the various filters used in this particular sharpening procedure that varying degrees of sharpening are applied; so, before attempting the procedure, I applied the Curves filter for a greater contrast of colors in the image.

Also, because the image is very low-resolution, I only used half of the sharpening procedure, opting to use the layers that are Gaussian-blurred as overlays, instead. The result is that the dip in the crook of the extended arm of the demon is more apparent, the fringe on that same arm is now distinguishable from the background, and the face of the hood is completely round (the cut of a demon's black cloak is important, as it is used to identify its variety correctly, since many demons of the same size—but of differing types—wear black cloaks):
BeforeAfter
NOTE | A contrast between the top of the demon's hood and the object on the table behind was created by cloning a lighter portion of the wall over the darker portion that blended too much with the hood, which made the demon look like he was wearing a pointy hat.
This technique is particularly important for images showing blanket or pillow demons, in that the improvement in contrast and sharpness it makes will often reveal a second demon's face overlapping the first, or a demon's face that could not otherwise be seen very well by others unfamiliar with the style in which such demons are created without the enhancements this procedure provides:
A color-enhanced and sharpened still frame, showing an apprehensive, beret-wearing pillow demon peers sideways out of a fearful eye, with his upper lip coiled in snare, bearing gritted teethFurther adjustments, showing yet another face of a pillow demon, which partially overlaps the first; it is squinting its eyes, and has a wide-open mouth that, like many demons, bears animalistic features
The high-pass filter sharpening technique highlights the three-dimensional nature of a cloaked demon, which is important in photos in which the background behind the semi-transparent demon is the same color as the demon itself.

In this photo, the demon's head could be glare from the surface behind him; but, with the procedure applied (see link below), you can clearly see that it is, in fact, a head (the quality of the rest of the photo notwithstanding):
Sharpening this still frame with the procedure highlights the three-dimensional quality of the head, which would not be present if the round, white circle shown in the original were anything but a head (click image to enlarge)
If the environment surrounding a demon in an image looks unnatural after applying this technique, then apply it only to the demon via selective sharpening. There are multiple ways to select only a portion of an image, many of which are described in tutorials posted to YouTube, as well.

Selective sharpening should also be used instead of border masks in images of blanket demons, wherever masks may be necessary, such as in blurry still frames, or as otherwise appropriate, such as images in which the face of the blanket demon is clearly defined by natural borders:
The demon's face was selectively sharpened, while color enhancements were made overallThe original, unenhanced still frameHighlighting it by using a semi-transparent mask, which is a black-filled layer set at 50% opacity

If you want to try and improve your images using the same method I did, follow the instructions in this video:


There is a second technique that works well, too:








#400 - SCIENCE | Sucker demons connect demons to humans for 'possession'

A sucker demon's omniscient knowledge of human biology, combined with its' physical characteristics specifically adapted to connect to both the human and demonic nervous systems, allows it to enable centurion demons to physically control the human to which a sucker demon is attached.

The tendrils of a tumbleweed-variety sucker demon are extended into the body of a human at various points, which create a neural pathway from the human to the demon, enabling the latter to send impulses from its brain to the human's network of nerves.

A common site in San Jose and its surrounding areas are people with a hazy, shimmering, ethereal-like crown on top of their heads (read SCIENCE | The ethereal haze and glow of demons (and ghosts) explained):
The possessed will exhibit the appearance of wavy lines above their heads
This is actually the external and cloaked portion of a tumbleweed-variety sucker demon that is attached to a person, and which is shown on my head in this video clip (because the cloaked sucker demon on top of my head is difficult to see, the clip repeats using a different video filter each time for better viewing):
Earlier this year, I made another (and better) video of a cloaked sucker demon on top of my head, slithering down the back of my neck:
The shimmer of air around such person's heads is caused by the refraction of light as it passes through the cloaked body of a sucker demon, which is extremely hot. The principles that apply here are the same as those to a mirage (whereby heat rising from pavement raises the temperature of the air above it, so that light passing through it appears to ripple and wave).

Following is a video showing a sucker demon attempting to attach itself to me in order to act as a interface for demonic possession:
Once the sucker demon has successfully attached to a human, a centurion demon enters the human by passing through it via the same ability it uses to pass through walls, which is somehow related to its cloak. The sucker demon then attaches to the equivalent portions of the demon's nervous system.

To make a connection between a human and a demon is not the only role played by the sucker demon; it also needed to anchor the demon to the human. That's because a demon must be cloaked to pass through people, walls, floors, etc., and matter affecting such a cloak cannot maintain enough traction to cling to, and cannot achieve the requisite momentum to keep up with, a human in motion.

A sucker demon, however, can affect both cloaked states simultaneously, thus allowing it to attach to both cloaked and uncloaked matter cloak at the same time. In fact, that is how a sucker demon is used to cause internal injuries without leaving external indicators (and, their precise knowledge of the human brain enables them to perform types of lobotomy-like procedures on victims of the Voices—and other—demons). In this case, the portion of the sucker demon attached to the human are uncloaked and the portions attached to the centurion demon are cloaked.
NOTE | To remove the uncloaked external portion of a sucker demon attached to you from yourself and others, read HOW-TO | Removing eye spider demons from your skin and HOW-TO | Vanquishing sucker demons from the bedroom.
By anchoring itself to the human using the uncloaked portions of its body, the sucker demon uses its connection to the centurion demon via the cloaked portions of its body to pull it along with the human.

Once a centurion demons achieves possession, it is a complex matter of overcoming any resistance offered by the human it possesses, as the demon must maintain enough concentration in order to "work their nerves" properly.

#399 - VIDEO | Sucker demon attacks at nude beach

Yesterday, as I tried to soak up rays at a private, nude beach in San Gregorio, California, I was attacked by a white, thread-like sucker demon that had so many tendrils, it looked like my hand was shooting lighting bolts onto my head:
At one point, the single tendril of the sucker demon spins into a web, encompassing my entire head in an instant
Like all other sucker demons, the one in the video from which this still frame was taken went right for the sore spot first created by sucker demons earlier this year, and which they have been drilling on nearly constantly since (shown, below):
Read more on the "hole" in my head that was created by sucker demons in Skull disfigured in just two days in sucker demon attacks and Voices Demons use sucker demons to deform, bore holes in skull
In this video, watch between my hands and my head to see the sucker demon; also, notice the tuff of sand it kicks up as it unearths itself from under my towel, near the end of the video:

This video clip shows what I go through for hours—or even days—at a time while trying to sleep. It also shows what a sucker demon really looks like as it attempts to connect to various nerves in the body, and find the tunnels that have been drilled in the skull by other sucker demons.

Before, I thought I was dealing with one tendril; but, I think now that was likely a decoy, as the video shows in several frames the sucker demon fanning out multiple tendrils, all across my skull, as is shown by the photo, above.

In several places, you can see several tendrils sticking up through the towel and into my head, as I attempted to show in a photo before in PHOTO | Sucker demons pass through fabric and anchor to face.

Clearly, not only have the Voices Demons extended their range of operations (read UPDATE | Voices Demons' range (and posse) now extends to San Gregario State Beach), but so have sucker—and other—demons.

#398 - VIDEO | Face-up profile of ornate blanket demon in clothes pile

The face-paint on a blanket demon found in Santa Clara (shown below) is nearly identical to the ornate style used by the blanket demons seen on video in Fremont and the blanket demon on video at the Watergarden in San Jose:
The upward gaze of a blanket demon, formed in a pile of dirty clothes (center-screen, in rear), which is wearing headgear similar to those in Fremont (below)
The still frame above was taken from a video showing a pile of dirty clothes on the floor, which was slightly moving at the time. There are several unformed faces emerging in the pile; but, the most distinct is on the bottom left, towards the back of the pile, which looks like a muppet wearing a Russian military hat, and an Abraham Lincoln-style beard (a beard without the mustache):

More blanket demons
This is not the first blanket demon this pile of clothes produced, as shown in VIDEO | Blanket demons and specters of demons merge; and, it is not the first gray-faced blanket demon I've encountered, either, as shown in Blanket Demon of My Youth, Face-to-Face:

Other blanket-demon videos can be found in the following posts:
The gray-faced blanket demon, which I know from my youth
Childhood blanket demon comes back to haunt. These posts contain videos and photos of the same blanket demon that first terrorized me at age 5, and then resumed at age 38:
  • Blanket Demon I: what I thought was my bedspread suddenly leaping at me as I lay in bed was actually a blanket demon, lifting itself up and towards me in order to scare me;
  • Blanket Demon II: my bedspread, which is actually a blanket demon, lurches towards me from the floor, and then falls again; and,
  • Blanket Demon of My Youth, Face-to-Face: I finally get a view of the face of the blanket demon haunting my bedspread by viewing it through a light-tunnel aperture (i.e., my cellphone battery cover, with the camera lens hole held at a distance).
Painted-face blanket demons. Over two dozen blanket demons surfaced at a Fremont hotel a couple of months ago, which used the stripes and patterns of a bedspread to draw and outline the features on their face and the ceremonial headwear they all wore:

Each face sported a full set of features, and all features were where you'd expect them to be. The creative and artistic use of stripes and patterns resulted in perfect alignment with those features, and are harmonically juxtapose to each other, in most cases (for example, some of the blanket demons aligned the stripes on their hats to perpendicular to the relative horizon).

Bathhouse blanket demon scowls from clothes pile. One of the most clear examples of a blanket demon in my collection, the bathhouse blanket demon apparently belongs to a variety similar to the painted face demons (above), in that its face is also painted, particularly, with the stripes on the fabric it used to create its likeness.
A blanket demon emerges from a pile of clothes on the floor of my room at The Watergarden
Unlike the painted face demons from Fremont, which rely primarily on stripes and patterns to draw the features (and define the borders) of their face as a substitute to shadow; rather, this blanket demon uses not only shadow for the features of the face that are depressed, such as the mouth, nose, dimple and eyes, it varied the shades of gray to imply proper depth.

Even more astonishing, is that this blanket demon affected an expression that, when you first see, makes you take pause, wondering what you did wrong; the other blanket demons stare blank-faced, and otherwise look like they are resting in a coffin.

#397 - THREAT | Voices Demons warn against exercise, threaten severe injury

Going to the gym (i.e., Fitness 19 in Sunnyvale, California) will result in severe injury, says the Voices Demons.
The Voices Demons are horrendous to people who improve their lives and health in this way; almost none of their people (i.e., those who support them) look—or act—healthy or make health-conscience choices of any kind

That's odd to me: I figured a bunch of skeleton and lizard men with fangs who spend all say hurting people would be all about life-affirming activities, and would express constant concern and a sincere interest in the issues people care about most.

Oh, wait! I'm thinking of angels and good fairies. Whew! Glad I clarified that. I wouldn't want to be mistaken as one of those people who can't tell the difference between a powerful and dangerous monster and not (or the difference between good and evil, for that matter).

This threat follows not only ongoing injury to my elbows and knees, but, lately, the burning of my fingertips, which is being done to me repeatedly.

The burn, which is completely internal, extends halfway down the first digit, and is caused by the black, needle-thin variety of sucker demons, specifically, by flying to a fingertip, partially enter it, and then radiates heat of some kind.

Afterwards, the fingertip is numb; and, even though some sensation  returns within a day or two, it is only slight. Inside the finger, it feels tough and thick. The only external indication of injury is broken skin on top of the fingertips.

I guess we'll see how much worse they will do when next I work out; however, in the meantime, it will be interesting enough to see if they have extended their range to Santa Cruz, as I intend to perform this test today, and how their aggressive and psychotic personalities react to my "insubordination" (that is to say, by going somewhere on my own accord, apparently).

#396 - SCIENCE | The ethereal glow and semi-transparency of cloaked demons explained

This article supplements Nature of the Demon Cloak Revealed, which presents the initial observations of the demonic cloak, and which forms the basis of the  fairly well-rounded explanation of how the cloak works as presented here. It is less-informed, and evidences lazy research on my part at the time it was written; however, even still, by sharing the observations contained therein, it showed, and continues to show, that a responsible effort is being made to keep readers apprised of the growing demon menace, which has virtually doubled nearly every month since.



The universally accepted image of a ghost is that of a semi-transparent, grayish haze, which happens to also describe the appearance of a cloaked demon perfectly.
The top half of the ghostly visage of my childhood demon, as he issues his edict against me in my bedroom in the middle of the night to other demons

But, in the case of the latter, that ethereal glow you see is not the soul of a recently departed; rather, it is the cloak of a living demonic entity, having a physical nature of which it is still possessed.
A still frame of a cloaked demon, in the dark, taken from a video made last night, both after sharpening and color enhancements and the original
Human researchers call this a near-perfect cloak, because you can still see a cloaked demon—as if they weren't trying to be invisible at all—and you can see through them—as if they are trying to be invisible (which you'd think would be the only reason to cloak), all at the same time. If the cloak were perfect, you wouldn't see them at all.

To help you visualize the semi-transparent nature of a near-perfect cloak, this video shows a demon affecting a near-perfect cloak:
NOTE | This video was enhanced per the guidelines provided in Blending Quicktime Video Layers to Penetrate Demon Cloaks, and, to a lesser degree, Blending Quicktime video layers to improve nightime videos, in order to highlight the demon, which was barely visible in the original video; hence, the explanation for the film-negative look.
Specific Quicktime blending modes were applied to duplicates of the original video layer to highlight the cloaked demon; without these enhancements to the original video, the demon can barely be seen
As you can see, most of the demon is invisible, while some parts are still visible, especially, the demon's head. There are two primary reasons for this:
  1. As light passes through the demon, it is refracted (polarization by refraction) by the demon's molecules, or, more specifically, the light is bent around the volume of air displaced by the demon, which is most visible along the surface of the demon, allowing the shape (or outline) of the demon to be seen. To visualize this in another way, think of a prism, which is clear, but is still visible because it bends the light passing through it; and,
  2. The haze is caused by the scattering of light (polarization by scattering), which occurs, they are scattered, which makes the demon to look as if it is casting a hazy, glow. This occurs when light particles impact the cloaked molecules of the demon, which, in turn, re-emit a light of their own, albeit in many different directions (versus a straight path, hence, the grayish hue). This haze is even more visible when the light is first reflected off of a nearby surface (polarization by reflection) prior to being absorbed by the demon's molecules. That's because light reflecting off a surface is already partially polarized, thereby amplifying the emission of polarized light emitted by the cloaked demon's molecules after being absorbed by them.
NOTE | These scientific principles are also applicable to haze sometimes seen in the sky, in that it is caused by the scattering of sunlight in an atmosphere made of otherwise invisible air molecules.
Different demons, different cloaking effects
All cloaks are near-perfect, in that a perfect cloak—or total invisibility—is theoretically impossible.

Consequently, the cloaks inherent to a each variety of demon are ranked by the nearest approximation to total invisibility. For example, the near-perfect cloak of centurion demons is one of the most highly visible of all cloaks, and is rated lowest among all other demons; whereas, Jawa-lookalike demons and hobgoblin demons have the least visible cloaks that have been detected.

In fact, it is not only the relatively poor cloaking ability inherent to this variety that enabled me to make the observations necessary to determine that a cloak was in fact used by demons, and to ascertain other facts about the cloak as presented in this post, but is also how the initial assumption that Jawa-lookalike demons and hobgoblins demons somehow achieved a perfect cloak was dispelled.

Even with sound scientific principles disproving the perfect cloak, this error is understandable. It was not common knowledge at the time that these demons could alter the flow of time around them, enabling them to fast-forward while the world plays slow. Adding lightning-quick speed to near-total invisibility significantly aids in avoiding of detection by sight. It was also not know that these demons can miniaturize themselves, an ability that was possibly derived from observations made of the natural resizing effect of hyperdimensional portal transfers, by which a demon employing such a portal is reduced to its typical size (ranging between in circumference of a pin to a pencil).

Plus, even without the advantages of increased speed and decreased size, their cloak shows more refinement than others. There is virtually no haze, just slight refraction, which is evident only by very thin lines of bent light that form the outline of the demon. As a result, you cannot see these demons when they're cloaked unless you know what they look like, and without looking directly at them with a good pair of eyes—and, only then with sufficient lighting and at the right distance.

Being virtually invisible by these merits made the observations required to achieve an awareness and understanding of the demonic cloak, unobservable, even with the growing collection of photos of these two varieties of demons in their respective cloaked states [see What a hobgoblin demon looks likesee also Jawa-like demons with glowing red eyes needle shoulder, trap muscles]), underscoring the aforestated advantage to others in the weaknesses of the centurion demons' cloak.
NOTE | Although it was the observations made first of the centurion demons' cloak that led to the discovery of the cloaking ability of Jawa-lookalike and hobgoblin demons, it was the observations gained by the awareness of the latter's such that completed the basic, overall understanding of the nature of the cloak of the former.
Also, they can change their size to ultra-small, which is an ability derived from the natural effect hyperdimensional portal transfers have on beings who use them (the size of a demon employing such a portal is, initially, the same size of the typical portal, which is the equivalent of a pinpoint or pencil.

The cloak of a sucker demon is also near-perfect, which is essential for clandestinely attaching itself on, and lodging itself in, the human body. The only tell-tale sign is the shimmer within the volume of air they occupy, as the light passing through the cloaked sucker demon is refracted by its heat (similar to a mirage).

Cloak of sucker demons used to burn, not just conceal
Sucker demons are employed by the Voices Demons and others to burn their victims at various times. For the past couple of weeks, they have been sending the thread-like, black variety into my fingertips, where they then heat up, thus burning the inside, while leaving the outside relatively untouched.

Following are three consecutive still frames taken from a video in which my hand just happened to pass in front of the video camera at the same time these sucker demons were either entering or exiting my fingertips:
The underside of my fingertips, in which multiple sucker demons are ingressing or egressingThe blurriness and poor image quality is not just due to motion, but to the EM field emitted by the cloak of sucker demonsThe last sucker demon to enter (or exit) my fingertip looks like nothing more than a splinter
NOTE | You can see an eye spider demon traveling under my skin in Eye Spider Demon Traveling Underneath Skin (view the web version) and Cloaked eye spider demon (?) blurs vision; eye spider demons are close relatives of sucker demons when it comes to cloaking ability, appearance (to the hair-like variety of sucker demons) and function on and within the human body.
Past videos showing cloaked demons
These other videos also show demons that were cloaked at the time they were made:


About this post
All of the statements made in this post are based on the daily observations and encounters with cloaked demons, and are supported by the basic scientific principles applicable to light. In other words, nothing I've seen appears to contradict anything I've read, and vice versa.

Still, to test my conclusion that the polarization of light causes a demon's cloak to be partially visible, and that the specific type of cloak can be categorized as a near-perfect cloak, one could simply try viewing a demon so-cloaked through a Polaroid filter. If the demon is no longer visible, that's because the light reflecting off of the demon (or emitting from it) is polarized, and is thus responsible for casting the ghostly haze. In other words, the result should be similar to the effects of a polarizing filter on the sky in a photograph, as demonstrated by these two photographs:
The left picture was taken without a polarizing filter; the right picture, with the filter, which eliminated certain polarizations of the scattered blue light from the sky [Source: Wikipedia.org | Optics]
The scientific principles pertaining to light as used in this post
For easy reference, the types of polarization of light that results in the partial visibility of the demonic cloak is listed below, with each followed by the explanation provided by a third-party educational web site:

Polarization by scattering explained
Polarization also occurs when light is scattered while traveling through a medium. When light strikes the atoms of a material, it will often set the electrons of those atoms into vibration. The vibrating electrons then produce their own electromagnetic wave that is radiated outward in all directions. This newly generated wave strikes neighboring atoms, forcing their electrons into vibrations at the same original frequency. These vibrating electrons produce another electromagnetic wave that is once more radiated outward in all directions. This absorption and reemission of light waves causes the light to be scattered about the medium. 
This process of scattering contributes to the blueness of our skies. This scattered light is partially polarized. Polarization by scattering is observed as light passes through our atmosphere. The scattered light often produces a glare in the skies. Photographers know that this partial polarization of scattered light leads to photographs characterized by a washed-out sky (see photo, above). The problem can easily be corrected by the use of a Polaroid filter. As the filter is rotated, the partially polarized light is blocked and the glare is reduced. The photographic secret of capturing a vivid blue sky as the backdrop of a beautiful foreground lies in the physics of polarization and Polaroid filters.

Polarization by reflection explained
Unpolarized light can also undergo polarization by reflection off of nonmetallic surfaces. The extent to which polarization occurs is dependent upon the angle at which the light approaches the surface and upon the material that the surface is made of. Metallic surfaces reflect light with a variety of vibrational directions; such reflected light is unpolarized. However, nonmetallic surfaces such as asphalt roadways, snowfields and water reflect light such that there is a large concentration of vibrations in a plane parallel to the reflecting surface. A person viewing objects by means of light reflected off of nonmetallic surfaces will often perceive a glare if the extent of polarization is large. Fishermen are familiar with this glare since it prevents them from seeing fish that lie below the water. Light reflected off a lake is partially polarized in a direction parallel to the water's surface. Fishermen know that the use of glare-reducing sunglasses with the proper polarization axis allows for the blocking of this partially polarized light. By blocking the plane-polarized light, the glare is reduced and the fisherman can more easily see fish located under the water.

Polarization by refraction explained
Polarization can also occur by the refraction of light. Refraction occurs when a beam of light passes from one material into another material. At the surface of the two materials, the path of the beam changes its direction. The refracted beam acquires some degree of polarization. Most often, the polarization occurs in a plane perpendicular to the surface. The polarization of refracted light is often demonstrated in a Physics class using a unique crystal that serves as a double-refracting crystal. Iceland Spar, a rather rare form of the mineral calcite, refracts incident light into two different paths. The light is split into two beams upon entering the crystal. Subsequently, if an object is viewed by looking through an Iceland Spar crystal, two images will be seen. The two images are the result of the double refraction of light. Both refracted light beams are polarized - one in a direction parallel to the surface and the other in a direction perpendicular to the surface. Since these two refracted rays are polarized with a perpendicular orientation, a polarizing filter can be used to completely block one of the images. If the polarization axis of the filter is aligned perpendicular to the plane of polarized light, the light is completely blocked by the filter; meanwhile the second image is as bright as can be. And if the filter is then turned 90-degrees in either direction, the second image reappears and the first image disappears. Now that's pretty neat observation that could never be observed if light did not exhibit any wavelike behavior.

[Source: The Physics Classroom: How Do We Know Light Behaves as a Wave?]