I didn't see a question in your first post. On Mon, Apr 5, 2010 at 3:44 PM, Jack Davis <jdavi...@yahoo.com> wrote: > I only read as far as about half of your first sentence. I didn't need to > read further as it was obvious you had missed the point of the question. > > Jack > > --- On Mon, 4/5/10, Godfrey DiGiorgi <gdigio...@gmail.com> wrote: > >> From: Godfrey DiGiorgi <gdigio...@gmail.com> >> Subject: Re: Define "blown out" :-) >> To: "Pentax-Discuss Mail List" <pdml@pdml.net> >> Date: Monday, April 5, 2010, 12:05 PM >> On Mon, Apr 5, 2010 at 10:27 AM, Jack >> Davis <jdavi...@yahoo.com> >> wrote: >> > I'll offer mine the nebulous term by saying that if at >> least some surface areas are rendered featureless by virtue >> of being too bright, I'd consider those areas "blown out." >> Many images can tolerate a certain amount of this condition, >> but it's amount is the criteria and varies with each viewer. >> Said areas must, of course, contain some available mask >> detail which defines the surface. >> > IOW, I'm not talking about an absolute ball of glare >> wherein no detail is discernible. >> >> There's nothing nebulous about "blown out". Consider areas >> of pure >> white with no detail as Zone 9 on the Zone System >> scale defined as >> follows: >> >> Zone 0 – key black or pure black – carbon or photo >> paper black. >> Zone 1 – near black – shadows in faint light or rooms >> without light. >> Zone 2 – dark gray/black – only subtle textures are >> visible. >> Zone 3 – very dark gray – distinct shadow texture is >> visible. >> Zone 4 – medium dark gray – slightly darker “black” >> skin, dark foliage >> or shadows in landscapes. >> Zone 5 – medium gray or 18% gray – darker “white” >> skin or lighter >> “black skin,” light foliage or the dark blue of a clear >> blue sky. >> Zone 6 – mid-tone gray – average “white” skin or >> shaded areas in snow >> on a bright, sunlit day. >> Zone 7 – light gray – pale “white” skin, a concrete >> walkway in sunlight. >> Zone 8 – gray/white, near white – distinct highlight >> detail, like a >> white wall in sunlight or brilliant surfaces in flat >> light. >> Zone 9 – known as key white or pure white – pure white >> paper or snow >> in bright sunlight. >> >> (Normally I think of the Zones as being from 1-10, but >> Ansel was a C >> programmer and did a 0-based count ... ;-) >> >> So, by definition, anything you want detail in is "blown >> out" if your >> exposure has placed it above Zone 8 on the above scale. >> >> Since I've never seen any application use 16-bit number >> scales to >> describe pixel values, you can determine what areas of your >> image are >> "blown out" in Photoshop or Lightroom using either a >> percentage scale >> or an 8-bit pixel value scale and floating the cursor over >> white-looking areas while looking at the information >> display panel. >> Presuming that the exposure did not go to saturation and >> there is data >> in those bright areas, you can place them in adjustment >> using the >> Exposure (aka white point) sliders. This table makes it >> easy ... >> >> http://homepage.mac.com/godders/zone-system-numbers.jpg >> >> EG: you have a near blown out area in a photo that you want >> to ensure >> images with detail on screen and in your prints. Float the >> cursor over >> it in Lightroom and see that it is currently at about 94% >> in all >> channels (or in one of them if that is the significant >> color of the >> area). Nudge the Exposure slider in the negative direction >> until it is >> in the range of about 85-88% to set that as the brightest >> point. Now >> make adjustments with the mid-tone, black point and Tone >> Panel to >> bring the rest of the photo into line with a satisfactory >> display. >> >> A certain amount of area at Zone 9 is fine, as long as it's >> not where >> you wanted to convey detail. Too much Zone 9 in an image >> generally >> looks bad. Another thing to be aware of is that many papers >> and >> monitor screens cannot display the full 10 zone scale very >> well, or >> have non-linear characteristics ... That's why calibration, >> profiling >> and testing for DR are essential to good quality image >> display, >> whether on screen or on paper. >> -- >> Godfrey >> godfreydigiorgi.posterous.com >> >> -- >> PDML Pentax-Discuss Mail List >> PDML@pdml.net >> http://pdml.net/mailman/listinfo/pdml_pdml.net >> to UNSUBSCRIBE from the PDML, please visit the link >> directly above and follow the directions. >> > > > > > -- > PDML Pentax-Discuss Mail List > PDML@pdml.net > http://pdml.net/mailman/listinfo/pdml_pdml.net > to UNSUBSCRIBE from the PDML, please visit the link directly above and follow > the directions.
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