Friday, 2 December 2011

HDMI Variations

We regularly get asked about the difference between the various HDMI standards so I thought I publish the brief definition from our glossary:

HDMI (High Definition Multimedia Interface) is designed for the easy transmission and control of video and - in the case of version 1.4 onwards - network signals. Version 1-1.2 supports 1920×1200 and 24-bit colour depth, version 1.3 adds 2560×1600 resolution and 48-bit colour (Deep Colour) and version 1.4 adds 4096×2160 (4k) resolution and networking. HDMI is backwards compatible with DVI.

Note that as of this writing there isn't much our there that will take advantage of HDMI 1.4 but Kramer do a number of HDMI 1.4 switches and distribution amplifiers.

©Ivojo Multimedia Ltd.

The JVC 3D Home Cinema Projectors

JVC have just launched the new DLA-X30, DLA-X70 and DLA-X90 home cinema and post production projectors and I thought a quick rundown of the projectors might be worth publishing as - in the flesh – they all look very similar.

First, the features they share in common:
  • 1920x1080 native resolution
  • 2D to 3D converter
  • 16-step aperture
  • 2x Zoom lens
  • 20Db noise level
  • 80% Vertical and 34% Horizontal Lens Shift
  • 3D Emitter and Glasses included
  • 2 HDMI Inputs
  • 1 Component (YPrBr) Input
  • 1 LAN Jack
  • 1 Screen Trigger socket

The Differences:

4K resolution with e-shift Technology-
Brightness (ANSI Lumens)130012001200
Colour Management7-axis7-axis
Colour Temperature (Xenon lamp mode)-
Picture Tone Adjustment-
Darkness and Lightness Correction-
Pixel Adjustment1 pixel increment1/16th pixel increment1/16th pixel increment
Screen Adjustment Modes3255255
THX Certification-THX 3DTHX 3D
Anamorphic Mode
Initial Calibration--
Auto Calibration--
Picture Data In/Out--
Lens Memory
Motorised Lens Cover-
Analogue VGA Input-

4K Resolution with e-Shift Technology

JVC have developed a new technology called e-shift for their DLA-X70 and DLA-X90 projectors which allows them to shifts their panels slightly and use each pixel twice per frame, almost doubling the resolution to 3840x2160). This gives a noticeable increase in resolution when viewing high definition films, a real improvement done in hardware rather than using software scaling.

Xenon Lamp Mode

The DLA-X70 and X90 feature a Xenon Lamp colour temperature mode. This allows the projector to reproduce the same colour temperature and gamut as cinema projectors, making the new models even more like going to the cinema.

Lens Memory

All three projectors feature 3 lens memories which can be used to store zoom, focus and lens shift and instantly recalled depending on what aspect ratio of image you are watching (4:3, 16:9, 2.35:1 etc).

Click Here to see JVC's projector range for home cinema and post production.

©Ivojo Multimedia Ltd.

Thursday, 1 December 2011

The Different Projection Technologies

For the projector buyers, the first choice you face is the choice of different technologies. Digital projectors broadly fall into two technology types, DLP from Texas instruments and LCD with its various derivatives, LCOS and D-ILA. 

DLP (Digital Light Processing)

DLP uses a Digital Micro-mirror Device (DMD) chip comprising thousands of micro mirrors, each of which corresponds with a pixel of the finished image. Each of these mirrors can be independently tilted to either reflect light towards the lens or away from the lens towards a light absorbing baffle. The easiest analogy is to think of each mirror being a light which is switched either on or off. The mirrors can tilt several thousand times per second so when an individual mirror is "on" more often than it is "off" we get more light reflected and when it's "off" more often than "on" we get less light reflected. This results in a lighter or darker shade of gray pixel. 

Adding Colour

The light reflecting off the DMD is - at this stage - in shades of gray and the next stage is to turn this image from grayscale to full colour. Between the DMD chips and the lens array is a wheel made up of coloured filter segments (red, green and blue in the simplest design). The colour wheel spins rapidly (50 times per second for a single speed wheel on a 50Hz supply) and the tilting of the mirrors is timed to allow light to either pass or not pass through each filter as the wheel rotates, producing a colour image. 

The "Rainbow" Effect

The result of this process is that DLP projectors build a colour image by displaying a series of static monochrome images. The rainbow effect - sometimes referred to as colour separation - occurs when the eye can detect these monochrome images in parts of the overall image produced. Most people are not susceptible to this problem but if you are then it can make single chip DLP projectors uncomfortable to watch. The problem has been somewhat alleviated recently with the development of faster colour wheels with more segments, causing the image to be refreshed more often each second.


LCD (Liquid Crystal on Silicon) is currently the most widely used projection technology in the world. Generally the systems used are made of 3 monochrome lcd panels, one each for red, green and blue. Light from the lamp passes through two dichroic mirrors, which separate the light into its primary colours. Each colour then shines on an lcd micro-screen, each pixel of which can either be "on", blocking light, or "off" allowing light through. The light that passes through enters a dichroic prism which re-combines the red, green and blue to produce a colour image which passes on to the projector lens. 

The "Chickenwire" or "Screen door" Effect

Until fairly recently people using LCD projectors have been able to see fixed pattern noise when viewing an image. This is the grid pattern made up of the gaps between individual pixels. As LCD technology has improved and resolutions have increased this artifact has become less and less of a problem. With high resolution lcd projectors it is reduced to the point where it can rarely - if at all - be seen from normal view distances. 


D-ILA (Direct-drive Image Light Amplifier) is a development by JVC and is sometimes referred to as LCOS (Liquid Crystal On Silicon). D-ILA operates on a reflective rather than transmittive principal. In other words, the polarised light (red, green and blue) is reflected by D-ILA chip's rather than be transmitted through the LCD chips. The D-ILA device’s reflective technique involves laying out the pixel address selection section and the light modulation section liquid crystal in three dimensions. The entire surface, except for the insulation section between pixel electrodes, is used as a reflective surface, so a very high aperture ratio is possible (making D-ILA more efficient than other technologies). The primary benefit to consumers of D-ILA is the ability to produce high light output whilst retaining high contrast without relying on lens iris adjustment.

For a list Ivojo's projectors click

©Ivojo Multimedia Ltd.