JVC adopts AVCHD, CMOS for new HD Everios

JVC Everio GZ-HD40

(Credit: JVC America)

Updated 6/23/08 with information about the sensors.

In an interesting turn, JVC's newest hard-disk-based HD camcorders--the Everio GZ-HD40, GZ-HD30, and GZ-HD10--will support AVCHD in addition to its traditional MPEG-2 formats. This is a great idea, at least for the interim, since it theoretically provides you with more flexibility in your video-editing options--especially if its AVCHD files aren't supported right out of the gate--and allows it to deliver high bit rate video beyond the 24Mbps maximum for AVCHD. Plus, the camcorders include FireWire (i.Link) interfaces, which many of today's models have dropped, for dealing with MPEG-2's HDV-compatible datastream.

The three models also integrate new CMOS chips; I've been waiting to hear back from the company with some details about the chips both of the CMOS chips, a 1/4.5-inch, 1.75-megapixel version for the HD10 and a 1/3-inch, 2.68-megapixel version for the HD30/40 represent a significant switch for JVC, which usually uses low-resolution CCDs. The sensors for these models should be high enough resolution to deliver a decent HD image. However, the press information provided is odd. The press release states:

This CMOS uses proprietary interpolation technology based on what JVC developed for its 3CCD cameras. This algorithm makes it possible to generate virtual pixel data from the red, green, and blue physical pixels, thereby providing image information that actually surpasses what's required for 1,920x1,080 Full HD imaging, or for 1,440x1,080 imaging in the GZ-HD10.

But the sensors are "high resolution" enough that interpolation shouldn't be necessary. And not only is interpolation undesirable, generating the "virtual pixel data" from a single chip is far less useful than generating it from three chips that each capture those specific primaries.

The key details on the new models:

	GZ-HD40	GZ-HD30	GZ-HD10
Hard-disk size	120GB	80GB	40GB
Format(s)	AVCHD and MPEG-2	AVCHD and MPEG-2	AVCHD
Sensors	1/4.5-inch, 1.75 megapixels	1/3-inch, 2.6 megapixels	1/3-inch, 2.6 megapixels
Max video dimensions	1920x1080	1920x1080	1440x1080
Maximum bit rate at highest resolution	17Mbps AVCHD 26.6Mbps MPEG-2	17Mbps AVCHD 26.6Mbps MPEG-2	17Mbps AVCHD
Hours recorded (highest/lowest quality)	10/15	6/33	1/3.3
Price	$1,299.95	$999.95	$799.95

Also, the GZ-HD40 comes bundled with a docking station. The three models are slated to ship in August.

[viskoundis]

when a CMOS chip is listed as 2.68-mega pixels 1/3 of those pixels are red 1/3 are green and 1/3 are blue.

True HD has 1080x1920 pixels each of which include the {red,green,blue} information. Just like your HD monitor has 1080 lines and each pixel has three colors (1080x1920 32bit pixels with 10bit per color).

Clearly in order to capture full HD information the CMOS must be at least 3x1080x1920 pixels, about 6 megapixels.
Another way to do the same thing is to use three CMOS or three CCDs with two mega pixels each.

Now JVC or any other consumer "HD" camera does not have 6 mega pixel CMOS or 3x2 mega pixel CCDs (or CMOSs), so in order to record the full HD format they have to interpolate.

A simple way to do the interpolation is, if for instance a CMOS has:

red -green-blue-red -green-blue-red =true

pixel sequence, one could fit a curve between the 1st second and 3rd reds and use the interpolated result in place of the green and blue.

red -green-blue-red -green-blue-red =true
-red -red -red -red =interpolated

Similar process happens for the green and blue pixels.

red -green-blue -red -green-blue -red =true
-red -red -red -red =interpolated
green -green-green -green-green=interpolated
blue -blue - -blue -blue -blue =interpolated

so this way you complete the missing bits.
The same is done for still photography as well. A 9 mega pixel camera is not really 9. It interpolated 9. The sensor chip has 9 mega pixels, but in terms or RGB you only have 3 mega pixels.

The results are fairly ok, but its cheating. That s why the professional (cinema) HD cameras cost $40k now. They have 3 full HD CCDs. That requires supper fast electronics for image processing.

I suspect that as electronics get faster and sensors get cheaper we ll get true HD cameras without interpolation for the consumer market.