DVL-Digest 700 - Postings: Index A VERY BASIC wideScreeen quest - (2) Wide screen cameras A VERY BASIC wideScreeen quest - "Perry" André metello: DV has 720 samples per line, or picture width. Normally (4:3) these represent 768 pixel points in PAL or 640 in NTSC. When in true wide screen mode (16:9), the picture is expanded by the display device so that the 720 samples become 1024 pixel points in PAL or 853 points in NTSC. In a true wide screen camera, the CCD sensors have more width in the 16:9 mode to give more samples to get the correct aspect ratio. This gives potentially more horizontal resolution in 16:9 mode than in 4:3. In consumer cameras the sensor is kept the same, but only 75% of the vertical scan is used. In PAL these 432 'lines' are expanded back to the required 576 by using a hardware interpolation device. In NTSC the numbers are 360 and 480 respectively. This interpolation reduces the vertical resolution considerably but the horizontal resolution is the same as 4:3. Perry Mitchell Video Facilities http://www.perrybits.co.uk/ A VERY BASIC wideScreeen quest - Adam Wilt When you shoot widescreen with DV, is it a sort of "cropping" from the > camera (that would reduce the 4x3 full frame area) and reduce the image > resolution (less horizontal lines) ?! See http://www.adamwilt.com/DV-FAQ-etc.html#widescreen and http://members.macconnect.com/users/b/ben/widescreen/index.html. Cheers, Adam Wilt Wide screen cameras - "Perry" Both cameras are set to default values, but exposed and color balanced 'manually'. The '500 had the DCC on but there is little in this picture to invoke its effects. Both cameras may be losing a little sharpness due to depth of field considerations. I would particularly point out the 'Black Crushing' of the VX1000 picture which is a characteristic of all consumer cameras. It results from inadequate gamma near black due to noise considerations. Other than this and the obvious drop in resolution, the VX1000 also has a couple of 'quirks': 1) The picture is only present for the analog 'Active Line Time', hence the black side borders 2) The 16:9 interpolation hardware causes a couple of lines to be scrambled at the top of the frame. Perry Mitchell Video Facilities http://www.perrybits.co.uk/ (diese posts stammen von der DV-L Mailingliste - THX to Adam Wilt and Perry Mitchell :-) [up] |
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