JVC monitor calibration software

Whilst at Channel Five recently I got to play with JVC's new monitor calibration software - it's for their DTV-series LCD panels and works using one of those little USB colourimeters (it supports several of the £150-gadget Tottenham Court Road specials). You use a DVI o/p from a PC to feed the monitor and hang the USB detector on the panel and via an RS232-USB connector the software models the monitor and uploads a 1D-LUT that makes the panel conform to a flat D6500 colour-space. Just the job for TV use.
There are a few caveats I can see;

• The JVC monitors don't switch in a different colour matrix when you go between 601 and 709 working (i.e. SD and HD signal) - the monitor assumes you'll be wanting reliable colour at HD and any SD work is just for content. Previous posts on this here.
  
• You calibrate the greys and whites using DVI (hence an RGB source) which only exacerbates my first point.
  
• Those little USB gagdets are a couple of hundred quid against a proper colourimetry probe which is a few thousand and a photo-spectrometer which is many thousand. Given how sensitive your eye is (particularly in the blacks) I'm not sure I'd place a lot of faith in something you'd buy in the high street.
  
• The software seems to do all it's modeling at 120Cd/m-sq - much hotter than you'd set the monitor for TV use and maybe twice as bright as if you were setting up a film grading display. This isn't as bad as HP's DreamColour range which start at 300Cd/m-sq!

Aside from those quibbles it looked quite good. I like the idea of being able to keep the LUTs for all your monitors and the fact that the software is looking to bring the display into compliance rather than "making it look good"(!)

For a class-1 device you need a mains earth!

We had a monitor that was giving people mains shocks off the SDi BNC connectors. I opened it up and there was no earth from the mains inlet to the metal chassis. No then - if you want to have no internal earth you have to have a plastic case and one other layer of insulation between the user and any current-carrying conductors (that can be a layer of air - but the device must be 'double-insulated' AKA 'class-2'). I hope this was a manufacturing fault and not a design oversight!
It's not unusual for equipment (particularly with a resonant or switch-mode power-supply) to have the internal earth float at half-mains (with a very high-impedance to the power-source, no real ability to deliver any current), but that's why you need a safety earth connection if you can touch the chassis-earth (on the BNCs, for example) and not get a little belt!

before - oh dear! - after - much better!

Eizo CG232W television monitor

I've been sent several monitors to look at over the last year that are essentially high-end computer displays that have been fitted with HD-SDi input and (with verying degrees of success) been sold as grading screens.

The first mistake that's often made is the amount of light output. The worst offender was the HP DreamColour range - peak whites at 500Cd/m2! BBC standard is to grade for TV at eighty and many film people are now setting monitors at sixty for long grading sessions. It is true that delta-E (the smallest perceivable colour difference on a standardised scale) decreases with overall illumination - at five hundred candelas per metre-squared you're nearly blinded. It might be fine for watching Toy Story but it's not what TV grading is about. I hear lots of colourist-wannabe's going on about how good a monitor looks without realising the most important thing is that a monitor is accurate - it conforms to the standard. Your TV at home should look good so you enjoy your movies etc. BUT your grading display should be brutally honest. Also - bear in mind that only about one in ten-thousand people have perfect colour memory (I don't) and so looking at a monitor for colour accuracy without a colourimetry probe (and not a £200 thing you bought for your Mac!) is pointless.

1. Whites - I'm so glad this display is kicking out a respectable sub-100Cd/m2! As mentioned we've seen several computer monitors that have been bent to look like TV displays that kick out many times more light than they should.

2. Blacks - Nothing special for an LCD - this looks like many LCD TV displays, the blacks are a bit lacking in detail. Ironically the cheap JVC DTV-20 series do blacks a bit better.

3. Interlace - the de-interlacer seems on par with the VuTrix Pro-24 - it struggles a bit with certain slow pans and zooms but seems to get captions (crawls and rolls) correct - better than the VuTrix. Some sub-frame events (fireworks going off, paparazzi camera flashes etc) upset it more than other monitors.

4. Resolution - looks fine. On a 0-15Mhz grating I can see the last section fine and there's no lacking in detail on real pictures.

5. Colour balance seems fine – next to a know good display both whites and blacks (well, 10% greys!) are v.close to D6500. It seems to track perfectly as well.

6. Backlight consistency – much better than the three VuTrix panels I’ve seen recently – as good as a Sony or eCinema DCM-23 (both >£15k panels).

I’d stress that I’ve looked at it very much as a TV monitor with my BBC / Illuminant-D eyes on. I’m not a film colour guy but TV colourimetry is my thing.

Vutrix HD Pro 24"

I had a chance to play with the new VuTrix 24" LCD monitor today. It is a native 1920x1080 display (actually 1920x1200 but it uses the top and bottom of the display for UMD data). I stuck it next to a new'ish BVM-20 which I'd just calibrated to illuminant-D and a white-point of 80Cd/m2.
I have to say that the blacks, white and overall colour balance out of the box was pretty good. To get it to track properly I had to set the gamma to 2.5 (rather than a 2.2 standard) and wound a bit of red into the whites. After that it was the best match I'd seen on anything under ten grand.
The one area where it really fell over was on caption-crawlers rendered at field rate - they were universally awful! Aside from that the de-interlacer looked good and the motion rendition was not bad next to the BVM.
I think I'll be definitely recommending it over the Sony LMDs and the cheaper eCinemas - but no match for the mighty DCM-23!

Their marketing bumph;

Standard I/P will be SD HD Auto sensing with "3 Gigabit 1080P" option (Fibre or Copper), with 1080P 50/60 Hz becoming a new standard for HD all monitoring will need to handle this format.
The Integrated Quad version can have 1 (for full frame mode) or 4 x 3G I/P's (Fibre or Copper).
It incorporates four independent video processing channels capable of receiving SD/HD/3G inputs, with internal synchronisation, allowing images to be locked to any input rate or to free-run.
Each image can be independently controlled to adjust aspect ratio, size, colour settings, input format, gamma and other settings.
Under-monitor display (UMD), tally blocks and audio presence meters are also included on all channels allowing a single display to be used in place of multiple units, resulting in significant reduction in space, cost and power consumption; benefits of significant advantage to space and power-constrained installations.
The displays also feature Vutrix's renowned colourimetry control and video processing resulting in images that are colour-accurate and with minimal motion and de-interlacing artefacts.
Network and serial control of all settings and data input allows complete flexibility in installation and operation in all applications.

eCinema FX24 monitor

A couple of years ago I was getting very excited about the DCM-23 monitor. We'd just started carrying it and I'd enjoyed a couple of days of training by Martin Euredjian. I fell in love with the DCM23 - I thought it was the most faithful monitor for HD around at the time - bar none. For progressive, HD work I thought it was a better monitor than the venerable Sony BVM-D24. As Martin had observed there were so many engineers and colourists who were determined not to admit that an LCD could be useful for grading - they weren't going to be impressed! The biggest moan was that the peak white output of the monitor was only 60 Candelas/M-sq. You find that as luminance tends to zero delta-E (the measurement of a 'just-noticeable-difference') gets smaller. The upshot is that if you are serious about grading you will drive your monitor a bit cooler than the average 80 Candelas/M-sq you'd set an edit suite monitor for (that aside I often go to Soho edit suites to calibrate the monitor and find the editor is happily running his display at 160 Candelas/M-sq!).

Small side-note concerning units of luminance - I know a lot of folks quote it in Foot Lamberts but this is a terrible measurement - it assumes monitors are a point-source of light (they aren't) and it is a mix of SI (Lambert) and Imperial (foot) measurements - don't use it! Far better to use the SI unit of the Candela per square metre.

Anyway - we recently got in on demo a new eCinema FX24 - it's their budget range LCD display for HD work and when I first fired it up I thought that it looked pretty good but a bit dim (the 60/80 things already mentioned). Today I had a chance to stick it next to a JVC-tubed monitor that I'd just calibrated (putting the white point at 6500k and 60 Cd/m2) and I was really disappointed. I estimate the peak-white light output to be around 20 Cd/m2 and although the colour in the blacks was OK the whites were somewhat off tending towards red. The monitor seemed to lack dynamic range with subtly graduated objects on the CRT looking very flat on the LCD. I turned the tube off to make sure it wasn't pulling my eye and felt the same way after watching half an hour of real-world cameras footage on the FX24.
Perhaps I was expecting another DCM23 but this was not up to that monitor's high standard. I'd say it is better than a Sony LMD-series LCD broadcast monitor (but that ain't saying much). I shall write a bit more when I have chatted further with Martin at eCinema).

Update: Martin from eCinema sent me some helpful comments;

....BTW, color temperature can be adjusted manually from the "Color Temperature"
menu. There are RGB sliders that can be manipulated to fine-tune the default calibration to your liking.

BTW #2, be sure that you've set the backlight to maximum brightness (hold down MENU button and press the UP or DOWN keys to adjust) and have allowed enough time for the tubes to warm-up (about 15 min).

Yes, FX is a budget monitor. Comparing it to a CRT wouldn't make it shine.

Here's a way to look at it. It is a great monitor for entry-level semi-critical applications. Most Apple FCP/Color users would be very well served by this monitor. It produces an image that is decidedly better than that on a Luma and also better in many respects than that on an expensive BVM-L230.

It if flattering that eCinema product is expected to live up to the highest of expectations. Thank you for that. However, the FX is intended to be what we like to call a "stocking stuffer" here. This means that it is a low cost, relatively non-critical utility monitor that can do well in a wide range of applications where cost is more important than performance.

-Martin

Tektronix vs Sony

This afternoon it was a stand-off between two giants of the broadcast hardware world - in the red corner was the test and measurement colossus Tektronix with their WVR7100 video waveform rasteriser. In the blue corner was Sony with their new LMD-2450W monster HiDef monitor.
The problem is that the XGA output of the Tek doesn't drive the XGA input of the Sony. Every other monitor was fine and every other device (well, mine and Simon's laptops) could light up the Sony at 1024x768 @60hz. After much puzzling I called Lee at Tektronix and he confessed that they didn't have a proper XGA timing device, rather than relying on some capacity on an FPGA and so consequently it runs at approximately 60hz - the Sony (it transpires) is very fussy. I spent the afternoon stripping off the syncs using a Procon processing DA and re-inserting it as separate H&V syncs, composite syncs and finally syncs-on-green but to no avail. I'd assumed it was a synchronisation issue.
Anyhow - while truffling about on the web I found this great Tektronix document on DVI test and measurement.
You'd best do a save as on that PDF - for some reason it won't open in the browser

Upgrading a Tek WFM7100

I demo Tektronix monitoring products and today I had to upgrade our loaner WFM7100. I'd done software on these chaps before and you can either do it over the web interface or via a USB stick on the front panel. In the case of this version 3.0 update (from the previous v1.25) you have to replace the front control panel, update the boot loader over the network and then use the USB stick to upgrade the instrement.

It's quite a change - it's made it into a WVR7100!
It seems a lot more stable and quicker. Also - it's not a touch-screen any more - it has the same front panel button set as a WVR (but arranged around the display). Using the Java app to control it you can't tell it apart from a WVR. Amazingly Tek ship this upgrade kit for free - given how well made the new front panel is I imagine they are taking a hit of hundreds of pounds per customer update.

I was tickled to see the attached label on the USB stick - you might kill your machine by doing the upgrade and if you do we'll bill you to fix it! I can report the update was entirely successful!
Actually - Tek upgrade procedures are always entirely straighforward and the instructions never leave anything to chance.

Another cool feature is that (being a dual-link HD-SDi machine) it now supports dual live inputs (at YUV 4:2:2, not RGB 4:4:4!) so you can be monitoring two video signals at once!

Burn-in on Sony LMD-230 series HD TFT monitor

It's not a great image (and I had to crank down the gamma to get it even visible) but what you can see here is the residual burn-in of colour bars on a Sony LMD-232 high-definition monitor. I would not have believed it until I saw it at the facility I was working at today. This monitor is two years old and I don't know if this kind of distortion is correctable. It must be the TFT panel itself - there is no way the backlight could take on the effect of bars. You can just see a yellow bar (where the blue bar would be) and where the green-magenta transition is you can see a magenta-green line. I do remember Martin Euredjian from eCinema Systems telling me that if you switch liquid crystal faster than the 15mS recommended by the manufacturer you run into trouble - the transistors become lazy and loose the ability to switch back entirely. This looks like what I saw on this Sony display.
While on the subject I thought I quote Martin on another of his TFT pet hates - grey-grey response times for monitors;

...this brings me to a topic that is being greatly abused by several monitor (and panel) manufacturers. To clarify, "monitor" means a finished product that an end user would purchase. In contrast to this, "panel" means the raw LCD element use by monitor manufacturers in fabricating their product.
This business of pixel response time has to do with how quickly the pixel is able to fully turn on (white) and then off (black).
If you were clicking out Morse code with a flashlight, you couldn't go any faster than the time it took for the light bulb to go from full off to full on and then full off again. For example, an LED flashlight can do this significantly faster than a conventional filament bulb flashlight.
In the context of LCDs, the only response time number that is of any relevance to film/video applications is a measurement taken from black to black. In other words, start with a black display and flash it to full white, returning to black. This is the only number you want a display manufacturer to quote you for response time.
Marketing guys have been known to bend things --a lot sometimes-- and so, it should come as no surprise that some are quoting response times that are simply not achievable within today's constraints. The latest one I heard during NAB is 6 milliseconds. I had people coming to the booth saying "how come yours couldn't do 6 milliseconds, "x" are saying that theirs do".
The critical question here was "Is it from black to black?". When asked, the answer was a resounding "no". People are taking measurements from some level of grey to another level of grey and quoting this as the display response time. You might as well be quoting the time it takes the average person to sneeze, because it would be just as irrelevant. Be aware of this and don't fall prey to contrived marketing.
Best-of-class response time today is somewhere around 15 milliseconds for all LCD's manufactured anywhere in the world. Why? Because there is only ONE liquid crystal fluid manufacturer that supplies fluid to the makers of ALL the good panels. The response time is largely a function of what the fluid can do. Today, the fastest fluid available can do about 15 milliseconds. Remember that and smile as a sales guy quotes you 2 millisecond response time. It might happen.

If you're interested you can read some of the other things he has to say on the cinematography mailing list.
If you're new to TFT displays for television and want a very good overview of how they work check out plasma.com

Unit Post and JVC monitors

This from UKPost.org

Tim Burton, Technical Manager, Unit Post Production, explains, "The MCR has enabled us to keep the edit suites cutting 100% of the time, and streamline how we execute ancillary tasks. The biggest gains have been in digital delivery and rendering times, by moving these tasks from the workstations to a 20 processor cluster we have seen a 5 fold increase in speed. Root6 completed the installation to an extremely high standard and It was a pleasure to work with Phil Crawley as he took the concept and helped develop it into a rounded solution within weeks. We have only scratched the surface of what this technology can offer and are continuing to expand and refine our systems and workflows."

I like those guy! I was back there today helping them out with some colour issues in their grading room. I discovered a few things about JVC SD/HD monitors - specifically;

• If you use one of their HD-SDi, SD, or mixed-mode cards you only get the Rec601 matrix. This means that when you calibrate for the tube for correct illuminant-D you wind up with a monitor that shifts either green or magenta (depending on which way you calibrated).


• If you install a component input card the colourimetry doesn't shift in this way - BUT the change in the raster causes the monitor to sit the picture down (the blacks get crushed) and you get a slight yellow cast in the white.

So, with all this in mind I've taken to calibrating those displays for HD and SD and handing the customer a set of instructions of changing the numbers when they start a new job.

ITU Rec 601 vs Rec 709 colourspace

Every superhero knows that in transitioning from standard definition television to high def we've adopted a different matrixing function for component to/from RGB conversion. The numbers for (old-skool) Rec 601 are thus;

Y = 0.299R +0.587G +0.114B
Cb = 0.564(B-Y) + 350mV
Cr = 0.713(R-Y) + 350mV

And the new kids on the block (Rec 709);

Y = 0.213R +0.715G +0.072B
Cb = 0.539(B-Y) + 350mV
Cr = 0.635(R-Y) + 350mV

So, not only has the weighting of the colours that make up the luminance path changed but the weighting of the colour difference signals is different. I've heard varying accounts of why they felt the change was necessary - I think it's probably to do with cameras and telecines (now be entirely CCD-based as opposed to the ubiquity of tubes when 601 was being formulated) and display devices (are we going to be able to buy a tube'd monitor by the end of this year?!). The new values better reflect the tri-stimulus nature of human vision and are less bound by the very noisy response of the blue-tube in image acquisition devices of yester-year.

However, one of the upshots of this is that digital devices that can receive an SD/HD-SDi bitstream have to be able to switch in the appropriate matrix. If that isn't the case then you'd notice a green cast on pictures if you switched between standards (going from HD to SD) or a magenta error going the other way. In the case of a monitor you'd have to re-calibrate the white point to D65.

The reason this has cropped up is that a facility (where I've just started to offer them colour calibration advice) has noticed that a monitor that was lined up correctly for HD working is showing the wrong colourimetry when being sent an SD feed. It's gone green (and not with envy! - oh, and that isn't the facility in case you're wondering!). It's a JVC DTV1700 series monitor which (although a cheapie at <£2k) has an EBU-phosphored tube (so you can calibrate it to 6500k at the white point). It looks like JVC's input card doesn't do the matrix switch. So, I'm wondering what other monitors do - I was sure the Sony BVM-D range did (but those monitors started in the mid-teen thousands of pounds). Any comments from people who've hit this before? As an aside the image (right - click it!) is from a very good Tektronix poster entitled Understanding Colors and Gamut - I have many copies (along with the equally exciting Understanding High Definition Video!) - give me a yell if you want one.

Pictures from the workshop

Mark came up to the workshop today to get some images for the new Root6 catalogue which is out soon. Click the title link to see various images of me and Tony doing stuff - calibrating a monitor, looking at an AutoCAD plot, splicing fibres, soldering connectors etc.

Why do peope use the Foot-Lambert?

As a means of measuring the light output of a display device it is an obsolete measurement. Far better to use the Candela per sq.m which is the SI unit and not some horrible mix of imperial and metric. For the record most edit suite monitors are run at a white point of 80 cd/m² which is approximately 30fL.

Mains hum

I spent the day at a facility we built a year ago trying to find the source of mains hum on a lot of their technical distribution. I've blogged about such things a couple of times before - here and here and always hope that people will accept advice about best practise and how to avoid such things.
Anyhow - eventually I tracked down the source of their problem - I had installed small isolators on those monitors (plasma TVs actually) that were powered off the domestic mains but one wall-mounted display had managed to snag it's video co-ax on the mounting bracket and hence grounded the screen to domectic earth before the cable hit the isolator. Even though I could only measure about 0.15v between the two earths it was enough to put big hum-bars on pictures (and pretty much every feed in the building!). I fixed the cable but as a bit of a belt'n'braces move I put video hum-buckers right in every feed leaving the machine room to equipment powered by the "cooking mains". That way even if cable damage occours in the future the isolator will protect the integrity of the technical earth.
I was there for six hours and didn't get offered a cuppa once - and we were doing it as a friendly favour!