Hi Neil - yes I agree, the 80Mp is only 80Mp for panchromatic light and even then the sampling is a grid and hence resolves at 30% less resolution in the 45 degree angle. If you want red detail in the 45 degree angle then you have 50% * 70% = 35% of panchromatic resolution. Hence, with nyquist/comb you have less than your 2500 (probably 2000lp).Neil Barnes wrote:As someone who's spent most of his career in imaging and signal processing of one sort and another (usually at much lower resolutions - broadcast TV) I'm watching this with interest... one thing which hasn't been discussed - and which the somewhat vague datasheet for the IQ180 doesn't specify - is exactly what is meant by '80 megapixels'. In pretty much every sensor of which I'm aware, the pixels for a colour 'block' are actually usually a variation on four pixels - two sensitive to green, one to red, and one to blue. Together that makes a colour sensitive (or monochrome, if you prefer) block but with only half the stated resolution - in both directions - in real terms.
Add to that the issue of both Nyquist limits and the comb filtering that occurs as you approach it if an optical low-pass filter is not used and it looks quite likely that the usable resolution of an 11000 wide sensor is going to be on the order of 'only' 2500 line pairs or so. On a 125mm wide 4*5 image that's roughly equivalent to 20 lines a millimetre...
As an aside - at the IBC exhibition earlier this month I got to see the NHK ultra-high resolution screen: 7680 x 4320 rgb pixels on an 85" diagonal. It is absolutely *stunning*... the camera (courtesy Ikegami) uses a colour splitter with 4000*4000 sensors - two for the green, offset half a pixel, and one each for red and blue. The system uses a 22+2 sound system (which strikes me as somewhat over the top, but which couldn't be adequately auditioned in the space provided).
Neil
The Bayer algorithm really muddies the waters in comparisons.
The 'screen' you talk about, is that a monitor screen? never mind... found it http://en.wikipedia.org/wiki/Ultra_High ... Television wow! nearly 100dpi on 85"!!