Archive for November, 2007

LCD vs Plasma continued

I came across an excellent website/blog by Carlton Bale which covers a wide range of digital television topics in detail.

I was interested to see his take on the LCD/Plasma discussion. Carlton’s observations:

  • LCD is better if there are windows or lights in
    the room because of the matte screen finish. New models, especially the
    120Hz models released in mid-2007, have much fewer problems with
    blurring when viewing sports or video games. If you want to connect to
    a computer, an LCD with direct pixel mapping is your best bet (search
    AVSforum for details.)
  • Plasma offers amazing black levels and, in
    general, a slightly better picture than LCD. If you are in a completely
    dark room with no potential for screen reflections, plasma is a great
    choice. Burn-in is not really a problem anymore unless you watch Home
    Shopping Network (with a single-color bar across the bottom) 100% of
    the time. (Most network icons in the lower corner are semi-transparent
    and don’t cause burn-in.)

I have to agree, in fact the plasma screens I’ve seen are very irritating to look at because of the reflections, oh and the immense amount of heat they throw out too.

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2k? OK! – 4K? OK…

We used to think that HD was difficult, then it was 2k and now 4k is the new goal in moving picture shooting & film post production (well I suppose 4k3D but I’ve not heard it mentioned much yet).

So what’s the latest? Well before I delve into that, here’s the background…

A couple of years ago I worked on the Midnight Transfer ‘DI From Day One’ project. This , at the time, was pushing at the edge of what was easily achievable. Not bleeding edge perhaps, but certainly leading edge stuff.

The aim was to create a complete rushes to graded master workflow in full 2k resolution. Until then all the grading that had been done on the dailies during the shoot, with the DoP was lost when it came to the final grade. Midnight’s idea was to create rushes in such a way as to preserve the grading information to give at least a starting position during the final grade.

The component parts were all in existence, or nearly so. Thomson’s Spirit 4K telecine/scanner had been around for a while, Filmlight’s Northlight scanner had been around too, for a little while.grading tools, such as Lustre and Baselight were established products with NuCoda’s product nearing readiness. SANs we plentiful, there was a fair choice of projectors and a couple of grading quality monitors to consider.

The only problem was overall system performance. The whole DI From Day One process requires speed.  Every process had to be real time, or faster, to ensure that the daily rushes could be made and delivered to set on time.

Parallel operations, such as scanning, grading, sound syncing and playout to tape deliverables must not interfere with one another or reduce the system performance. The difficulty was no one else had done this in the UK in quite the same way.

There were bigger SANs (though ours at around 100TB was certainly big for the time) used in the graphics world which didn’t need our high data throughput and there were faster SANs, but these were all single operations that weren’t moving such large files in and out simultaneously.

The choice came down to who could demonstrate:  a) a minimum of 2 streams of real time 2k data in and out of their system and b) persuade us that they really understood the workflow we wanted to build.

In the end DVS won the contract to supply both their incredibly flexible Clipsters and their just launched (and then still in development!) DVS-SAN.

One of the key enablers was Thomson’s Bones, the Linux based link between the fast Spirit 4K and the SAN.

Midnight were able to use the functionality within Bones to achieve the essential dailies throughput whilst allowing the two grading rooms to pull material for grading from the SAN without compromising the rest of the operation.

Anyway, with a bit of arm twisting, careful analysis of the available building blocks, the DI From Day One concept was achieved and has been running smoothly ever since. (see the press release from the time press release from the time:Digital Cinema Report).

But what of 4K? Since the Midnight project was launched, the DCI has specified the full 4K workflow and it is the new gold standard for new facilities. If I was doing Midnight in 4K what would need to be different? Is everything 4kish off the shelf now? What implications are there for pulling these much larger files around?

I will be investigating these issues over the next few weeks. Stay tuned and feel free to comment!

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Article comparing LCD & DLP Technologies

Here is a handy article that compares the pros and cons of LCD & DLP technologies.

There have been a lot of advances since this was written (back in 2004) however the fundamentals remain relevant.

It is also worth taking a look at DLP using LED light sources.

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Projector Choice – Rule of Thumb

Ambient light and light output of the projector

From the Projecta website:

” The clarity the image should possess in order for it to be perceived well (quantity of light which comes from the projection screen) depends on the quantity of ambient light present, the reflection value of the screen fabric and the light output of the projector. For an optimum, legible projection quality, the light output of the projector, the size of the projection screen and the reflection value of the screen fabric should be attuned to one another.The following rule of thumb applies in calculating this:

Output ANSI-Lumen projector
LUX = ———————————— X reflection value (=gain)
Surface area of screen in m.

LUX = 100 too little ambient light
LUX = 400 normal ambient light

The perceived amount of light that is reflected by the projection screen is expressed in LUX. For an optimal image quality, the ratio between the LUX value of the projected image and the wall behind it should be a minimum of 5:1. A rule of thumb which may be used is that with normal ambient light, when the light output of the background is approximately 80 LUX, the value of the amount of light (LUX) that is emitted by the projection screen should be roughly 400 LUX. If the amount of ambient light is too low, the LUX value of the background is approximately 20 which means that the LUX value of the screen should be around 100.”

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