Are there any programs that can convert color infra-red photos to actual color?
in [Digital Cameras]
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From: David J Taylor on 17 Jul 2010 10:01 "Kennedy McEwen" <rkm(a)nospam.demon.co.uk> wrote in message news:cUF4XZFUFbQMFwYk(a)kennedym.demon.co.uk... > In article <i1rugq$sum$1(a)news.eternal-september.org>, David J Taylor > <david-taylor(a)blueyonder.co.uk.invalid> writes >> >>Put briefly: to see thermal radiation from a hot mug requires an imager >>sensitive in the 10um region of the spectrum, > No it doesn't, 3-5um works just as well - better in fact. > >> which might require a cooled detector. > Not at 10um it doesn't. > > The radiation from the mug may peak around 10um, but with modern cooled > sensors its the radiation contrast that determines the optimum band. The > contrast at mug-like temperatures in the 3-5um region is about 4%/degC > and roughly double what it is at 10um. > -- > Kennedy I was trying to keep it simple! Note that I said "might require a cooled detector", not "will". Accepted that the contrast is greater, but you then quote the use of a cooled detector. All space-based instruments which I know about use cooled detectors, for looking at earth-like (i.e. mug-like) temperatures, and the NET is typically lower in a 10um detector than in a 3-5um one. The point remains to distinguish between far-IR and near-IR uses of the term "infra-red" (and those tend not to be hard and fast terms either). Cheers, David
From: David J Taylor on 17 Jul 2010 15:48 "Kennedy McEwen" <rkm(a)nospam.demon.co.uk> wrote in message news:0wDy+YEO9fQMFwfN(a)kennedym.demon.co.uk... > In article <i1sd2s$ajn$1(a)news.eternal-september.org>, David J Taylor > <david-taylor(a)blueyonder.co.uk.invalid> writes >> >>I was trying to keep it simple! > Trying being the operative word. To avoid exactly this level of detail. >>Note that I said "might require a cooled detector", not "will". > But you said "requires...10um", it doesn't and if you choose to work at > 10um it certainly doesn't require a cooled detector. > >>All space-based instruments which I know about use cooled detectors, for >>looking at earth-like (i.e. mug-like) temperatures, and the NET is >>typically lower in a 10um detector than in a 3-5um one. >> > I assume that is because they are "looking" at each spot for a limited > time, rather than operating to full performance without time > limitations. Modern cooled infrared detectors are more like the sensors > in digital cameras, matrix arrays. In these devices the exposure time > is limited by the well capacity (just as the exposure of digital camera > sensors to avoid saturation is limited by the pixel storage capacity). > When you are storage capacity limited, instead of time limited, as with > modern high performance cooled sensors, the NET of 3-5um detectors is > around half that of an equivalent 10um device. For example, two > otherwise identical devices, well into BLIP performance: > http://tiny.cc/wnyeb is a 3-5um device with NETD of ~17mK while > http://tiny.cc/f0032 is its 10um counterpart with NETD of ~32mK. > > Or, in exactly the same device which is sensitive in spectral regions: > http://tiny.cc/ni4dw when operating dedicated to each band the 3-5um > NETD is ~11mK, whilst the 8-10um NETD is ~22mK. > -- > Kennedy Yes, I'm talking scanned rather than staring arrays. Thanks for the further info. Cheers, David
From: Peter on 17 Jul 2010 20:45 "David J Taylor" <david-taylor(a)blueyonder.co.uk.invalid> wrote in message news:i1rugq$sum$1(a)news.eternal-september.org... > "DanP" <dan.petre(a)hotmail.com> wrote in message > news:46365b3d-a169-4fa0-8995-a96da2cdde1f(a)e5g2000yqn.googlegroups.com... > [] >> The information from an IR image has nothing to do with the colour. >> A hot green mug will look different in IR than a plant with the same >> shade of green. >> So you cannot map IR to visible colour. >> >> DanP > > Be careful not to confuse near-IR with far-IR. With digital cameras and > film it's the region just beyond the red end of the visible spectrum which > people call "IR" - a wavelength of ~0.8um. Here, the prime difference is > that the reflectance of vegetation is much higher and hence the > characteristic appearance of monochrome IR images. > Almost! Chlorophyll is transparent to waves in the near IR spectrum. Hence it appears to be white. Similarly many clothing dyes are transparent in that spectrum and also appear white. Particles in the air cause the sky to appear blue. In this spectrum these particles do not reflect the energy waves and thus appear black. BTW I have submitted an IR photo in the SI. -- Peter
From: David J Taylor on 18 Jul 2010 01:37 "David J Taylor" <david-taylor(a)blueyonder.co.uk.invalid> wrote in message news:i1t1et$fp4$1(a)news.eternal-september.org... [] > Yes, I'm talking scanned rather than staring arrays. ... and with resolutions today of 3712 x 3712 pixels, and in a few years time of nearer 11,000 pixels square. Mechanically scanned, with mirror optics, covering 0.6um to 13um with a set of detectors. Cheers, David
From: David J Taylor on 18 Jul 2010 01:44
"Peter" <peternew(a)nospamoptonline.net> wrote in message news:4c424ec1$1$5550$8f2e0ebb(a)news.shared-secrets.com... [] > Almost! > Chlorophyll is transparent to waves in the near IR spectrum. Hence it > appears to be white. Similarly many clothing dyes are transparent in > that spectrum and also appear white. Particles in the air cause the sky > to appear blue. In this spectrum these particles do not reflect the > energy waves and thus appear black. [] If anyone would like to know a little more, there's a training module here, entitled: "Monitoring Vegetation From Space". http://www.satreponline.org/landsaf/index.htm This section may be of particular interest: http://www.satreponline.org/landsaf/navmenu.php?page=3.0.0 Cheers, David |