Category Archives: Technical

“No glasses” 3D Holograms?

Light Field Labs has raised an additional US $28 million in funding to develop and produce free air holographic display technology. They are said to have a working prototype now and the additional funding will enable them to scale up to an actual product.

The aim is to create holographic objects that appear to be three dimensional and float in space without head-mounted gear such as augmented reality or virtual reality goggles.”

Source: Light Field Labs : 3D Holograms no glasses Deep Dive – fxguide

The principle people behind the technology had developed the Lytro camera technology. As best I can tell, it may be similar to a digital implementation of a conventional, analog, film-based hologram. In the original hologram technology, you look at a flat image that is, basically, like a window pane. As you move to the left or right, you see the true 3D image visible from that point in space. In the laser-based hologram, the window pane is a film that has recorded light interference patterns.

From the description down the page, here, my interpretation is they have created a currently small window pane that is replicating the light interference hologram concept, but in the digital domain. Obviously, it takes a tremendous amount of computational horsepower and for video, high bandwidth, both of which are becoming available as tech advances.

I presume, also, that this technology can be used to project objects in front of the viewing plane, as is done in stereoscopic 3D. In other words, actors or objects can be appear to be between you and the viewing screen – or behind the screen.

This tech creates true 3D that does not require glasses for viewing.

Common photography aspect ratios and print sizes are arbitrary

Still photography and motion pictures have, over history, used aspect ratios such as 4:3, 3:2, or for printing 4×5, 8×10 and what not.

These choices were arbitrary – based on practical design and implementation considerations of the time.

The popular 8×10 paper size came from how fine paper was originally manufactured and sliced down to size by hand, in Dutch paper mills and corresponded to the equipment size readily handled by the length of the arms of the mill workers. These cut 8×10 sheets were later cut to create 8×5 sheets, which in turn were sliced to 4×5 sheets. (I could not verify these claims independently but could not dispute them either. Of interest, the 8 1/2 by 11 inch sheet of paper we take for granted also seems to have come out of similar issues and stuck with us because of practical issues regarding manual typewriters, issues that no longer exist today.)

The 35mm standard came from early still photo film which happened to be 70mm wide, but was split down the middle by Thomas Edison to save money for making a movie film. After adding holes along side the film for pulling the film through their movie camera, the image area became 24mm wide measured across the film. Each image was limited to 18mm in the length direction – becoming a 24 x 18mm or 4:3 aspect ratio image.

This film was then adopted for new still cameras (Leica) which chose to double the 18mm to 36mm, hence 24mm by 36mm (the well known 35mm format) in a 2:3 (or 3:2) aspect ratio. The 1:1 ratio photo came from waist-level viewfinder cameras – since it was not easy to turn the camera sideways, they chose a 1:1 ratio.

The result is that today’s modern digital camera and print aspect ratios are arbitrary and based on design choices that occurred out of practical considerations in the 19th century and the early 20th century.

Source: history – What historic reasons are there for common aspect ratios? – Photography Stack Exchange

And then there is the 16:9 aspect ratio of HD, which is the compromise that came out of a committee that wanted to create a new TV standard to deal well with older 4:3 content and wide screen content which is wider than 16:9. Basically, an arbitrary compromise value.

There is also similar information on how did we end up with audio reel-to-reel tape recording at 7 1/2 inches per second? I was told it was because this was the speed at which 16mm film, with an optical soundtrack on the film, operated. I could not quickly verify if this was true though and could only work out that 16mm film seemed to go through at 7.1″ inches per second at 24 fps.

Using 2 cameras to create fake narrow depth of field images

Small sensor cameras – such as smart phones and point and shoot cameras – are unable to create significant blurring of the background or foreground. Narrow depth of field is mostly limited to large sensor cameras – or to long telephoto shots.

But, two camera sensors may be used to measure depth in the scene. One camera is used for the actual photo and the second for depth. Parallax, or the difference between the two camera images, varies by distance to the subject. This information is used to blur the original image based on distance to the subject. (Blurring is done by averaging local pixels together using a simple average or a weighted average.)

This means that software creates the narrow depth of field effect, rather than large sensors and expensive lenses.

The HTC One M8 smart phone has this feature today. The linked article gives examples of how this works, in practice. Take a look at their sample photos!

We compare the HTC One M8 camera with a Fuji X-M1 to see what its bokeh-style effects are really like.

Source: HTC One M8 Camera vs A Proper Camera: Fake Bokeh On Trial

Note that if the cameras are very close together, as is typical on a smart phone, the ability to accurate measure distance a long ways from the camera is greatly diminished. Image resolution and interaxial spacing both impact the capability of this feature.

Rumors are that the iPhone 7 will feature dual cameras for the same reason – to create narrow depth of field photos using tiny sensor cameras built in to the phone.

Currently, the best narrow depth of field comes from DSLR full frame cameras and expensive, large aperture lenses.

But post processing software is eliminating many advantages of the full size cameras. Modern post processing noise reduction enables many small sensor cameras to perform more like their big cousins in low light. And now, with dual cameras and depth processing, little cameras may soon deliver narrow depth of field at lower cost than the big guns.

This should be worrisome to the DSLR makers. Particularly as increasing numbers of shooters would prefer to travel light – and not have to carry big camera bodies and heavy lenses.

StereoStitch Introduces Real-Time 3D VR 360 for live 3D VR

Source: StereoStitch Launches a Real-Time 3D 360 Video Stitching Software for VR Live Streaming

Playing 3-D video games can boost memory

Playing 3-D video games can boost memory formation says a study from UC Irvine

Source: Playing 3-D video games can boost memory formation, UCI study finds

The study is published in the Journal of Neuroscience.

(Go Anteaters! My undergrad degree in computer science was earned at the University of California, Irvine 🙂 )

Canon announces 250-megapixel image sensor

Canon has today announced a new ultra-high resolution CMOS image sensor that packs approximately 250 megapixels into an area smaller than a United States postage stamp.

Source: Canon announces whopping 250-megapixel camera sensor – TechSpot