Archived posting to the Leica Users Group, 2007/11/11
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Hi Henning, Might be, but I was just stating that if one offers images for comparison, they should be taken in the same circumstances, or, if that were not the case, at least with levelled ones. If you want I can post both shots levelled. Took me half an hour. Would have been easier if the were from the start. Philippe Op 11-nov-07, om 00:54 heeft Henning Wulff het volgende geschreven: >> This sounds like a very plausible theory, Anders. >> >> As I stated before, I don't doubt Len's observation. But -and as >> an answer to Henning- the 2 visual proofs of this observation were >> not were not really made in identical circumstances. >> That's why I suggested to documented them in a similar conditions. >> Even from his low res jpegs, I did the test, balanced them (black >> point, white point, mid gray) and put them in Lab colour -the >> widest color space as you may know- to make them comparable*. >> There still is a visible difference. But at least the comparison >> has been made on a par level. >> >> So let's not start doing critical image comparisons in different >> conditions, on different screens and with low res sRGBs if we want >> to use these a studying material. >> Even if visual comparison does not give the right explanation for >> the reason of succes for this treatment. >> >> Philippe > > > I have seen thorium glass elements that have aged. I've also seen > many lenses with fungus. Fungus is a surface condition. This is an > internal condition. > > Changing the colour model from RGB to LAB doesn't help per se; it > might help you quantify the differences better if you are more > familiar with that model but it doesn't have anything to do with > the colour space > > As far as colour space is concerned: yes, there are a lot colour > spaces with wider gamuts, such as Adobe RGB or even better Prophoto > RGB, but that is little help when the original is a small sRGB > image. But even here, the differences are readily measurable and > discernible and critical comparison is not necessary to see that > there is a definite difference. If looking at the low-res sRGB jpgs > goes against the grain, read Len's description. He feels that the > jpgs are representative of what he sees, so let's accept it. > > As I said, the mechanism is not clear to me nor have I been able to > find out what it might be, but it obviously responds to low energy UV. > > > -- > * Henning J. Wulff > /|\ Wulff Photography & Design > /###\ mailto:henningw@archiphoto.com > |[ ]| http://www.archiphoto.com > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >