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Wednesday, November 22, 2017

#Language and Life

#Language and Life


Seeing History: The long dark night

Posted: 22 Nov 2017 04:30 AM PST

What we see today is vastly different from the world of our ancestors. Yet when we look at paintings from two hundred or more years ago, we view them with modern eyes, and modern brains behind them.

It is second nature now that, if we see one edge of an object with linear blur, we interpret that as arising from its motion. Yet before the introduction of photographic images, no human had ever seen motion blur. It is an artefact arising from a relatively modern technology, a result of camera shutters and exposure times, not something present in nature, nor in our mental processing of images. To an Old Master or their patron, motion blur would have been meaningless.

We cannot unlearn our rich visual experience in order to better appreciate older paintings, nor should we attempt to do so. What I am going to attempt in this new series of articles is to provide some insight into what has changed, and when, so that we find ourselves better able to understand the artist’s intention.

It is as much an exploratory journey for me as I hope it will be for you: I have been looking for reference material on this topic for some time, and have failed to find any of value. I thought that I might have been pre-empted by Mark Cousins, whose recent book The Story of Looking could have covered common ground; marvellous though it is (and I highly recommend it as a journey through images, including many paintings), he does not seem to have tackled these issues.

There is no painting without light, and much of painting celebrates and explores light and its effects on figures, objects from the world around us, and that world itself. Over the last few hundred years, human exposure to lighting, and our lit environments, have changed more obviously than anything else as important.

anonearthlights2002
Creator not known, Light pollution in Europe, 2002, further details not known. Wikimedia Commons.

I love flying in a clear sky at night, looking down at the densely-lit areas in cities, and scattered pinpoints out in the wilds. Some of the most remote places are no longer fully darkened at night, as this image showing light ‘pollution’ in Europe in 2002 demonstrates. Three hundred years ago you would barely have been able to see anything apart from the earth’s dark albedo.

nalilordtokyonight
Nalilord, Tokyo streets by night shot from Tokyo Tower (2011), photograph, further details not known. Image by Nalilord, via Wikimedia Commons.

The great cities of the world, like Tokyo, are now light twenty-four hours every day, irrespective of season.

During the winter, the most populous parts of Europe and North America have limited periods of daylight, and heavily overcast skies often greatly reduce available light. Today we simply switch the lights on.

The city of Paris has led the world in the introduction of street lighting: its first light, a candle lantern, was installed in 1318, and by 1669 the few street lights were being lit even in moonlight during the winter months. Paris installed its first gas lamps in 1829, each providing the equivalent light of ten candles. By 1870, there were over twenty thousand gas street lamps across the city. Electric ‘candles’ were first introduced in 1878, and by 1900 there were over fifty thousand street lamps, most either incandescent gas mantles or open arc lamps.

delatourpenitentmary
Georges de La Tour (1593–1652), Penitent Mary Magdalen (1628-45), oil on canvas, 113 × 93 cm, Private collection. Wikimedia Commons.

Whether wealthy or poor, the subject of this Penitent Mary Magdalen 2100 years ago, or the artist Georges de La Tour when he painted her in 1628-45, the staple forms of light were candles and oil lamps. These emitted around a candlepower of luminous intensity, in modern units about 1 candela.

delatourmagdalensmokingflame
Georges de La Tour (1593–1652), The Magdalen with the Smoking Flame (date not known), oil on canvas, 117 x 91.8 cm, Los Angeles County Museum of Art, Los Angeles, CA. Wikimedia Commons.

The larger floating oil lamp shown in de La Tour’s The Magdalen with the Smoking Flame must have been a little more powerful, perhaps the equivalent of two or three candles when it was working well.

elsheimercereshecuba
Adam Elsheimer (1578–1610) and workshop, Ceres at Hecuba’s Home (c 1605), oil on copper plate, 30 × 25 cm, Museo Nacional del Prado, Madrid, Spain. Wikimedia Commons.

If you were a goddess like Ceres, as shown in Adam Elsheimer’s Ceres at Hecuba’s Home (c 1605), you might have had an even larger candle, but it wouldn’t have come close to the 10 candelas of early Parisian gaslights.

elsheimerjupitermercurypandb
Adam Elsheimer (1578–1610), Jupiter and Mercury with Philemon and Baucis (1609-10), oil on copper, 16.5 x 22.5 cm, Gemäldegalerie Alte Meister, Dresden. Wikimedia Commons.

Elsheimer’s marvellous painting of Jupiter and Mercury with Philemon and Baucis from 1609-10 gives a very good impression of what would have been quite good everyday indoor lighting prior to the introduction of kerosene lanterns from about 1850.

vanhonthorstsoldiergirl
Gerard van Honthorst (1592–1656), The Soldier and the Girl (c 1621), oil on canvas, 82.6 x 66 cm, Herzog Anton Ulrich-Museum, Braunschweig, Germany. Wikimedia Commons.

Gerard van Honthorst is another artist whose depictions of lighting at night are so informative – here in The Soldier and the Girl from about 1621.

menzelfluteconcert
Adolph Menzel (1815–1905), Concert for Flute with Frederick the Great in Sanssouci (1850-52), oil on canvas, 142 x 205 cm, Alte Nationalgalerie, Berlin, Germany. Wikimedia Commons.

The rich could afford chandeliers full of candles, as shown in Adolph Menzel’s Concert for Flute with Frederick the Great in Sanssouci (1850-52). This concert would have taken place about a century earlier, in about 1750. Those very expensive chandeliers offered around 25 candlepower or candelas, but were inefficient at directing their light. Note that each musician still needs their own candle close to their score.

The best way to appreciate what life was really like is to watch Stanley Kubrick’s marvellous movie Barry Lyndon (1975). Kubrick went to great lengths, including using specially-made wide aperture lenses, to shoot his movie in realistic lighting conditions: predominantly natural daylight outdoors, and candlelight indoors. The look of the film is so faithful that it has often been likened to that of eighteenth century paintings.

Even during the hours of daylight, rooms indoors were often lit by relatively weak light. The rich could afford to have their windows glazed using small rectangular panes of glass which were manufactured ingeniously from blown cylinders or flattened disks. More ordinary people were generally unable to afford even small glass windows until the seventeenth century.

It wasn’t until around 1800, when steam engines were applied to the production of cast glass, that larger sheets of glass could be manufactured reliably. During the first half of the nineteenth century, glass manufacture advanced greatly, reaching a peak with the construction of the all-glass Crystal Palace in London, in 1851. From then on, it was more feasible for an artist’s studio to have much of its north-facing aspect made of glass, to ensure good levels of daytime illumination for painting, even in the winter.

(Tradition in the northern hemisphere has long required studios to depend primarily on light from the north, as it is suffuse rather than direct and dazzling, and more constant in colour temperature during the day, and over the seasons. However, this also results in lower levels of illumination.)

vanschendelbarketbycandlelight
Petrus van Schendel (1806–1870), Market by Candlelight (1865), oil on panel, 46 x 33 cm, location not known. Wikimedia Commons.

In many towns and cities, even well into the latter half of the nineteenth century, candles were still widely used to light outdoor events, such as Petrus van Schendel’s Market by Candlelight (1865). This painting captures well the resulting soft, romantic glow, and the hazy atmosphere which was a common accompaniment.

vangoghpotatoeaters
Vincent van Gogh (1853–1890), The Potato Eaters (1885), oil on canvas, 82 × 114 cm, Van Gogh Museum, Amsterdam, The Netherlands. Wikimedia Commons.

The lighting effects of relatively primitive oil lamps dominate some paintings, most famously Vincent van Gogh’s The Potato Eaters (1885).

backervedlampelys
Harriet Backer (1845–1932), Syende kvinne ved lampelys (By Lamplight) (1890), oil on canvas, 36 x 44 cm, Galleri Rasmus Meyer, Bergen. Wikimedia Commons.

The Norwegian Harriet Backer here shows the starker effect of a kerosene lamp, in her Syende kvinne ved lampelys (By Lamplight) (1890). For many around the world, such kerosene lamps with their 100 or so candlepower are still their mainstay lighting, in the absence of reliable electric supplies.

Humans lack the highly-sensitive night vision of nocturnal predators, such as cats, but we can still see remarkably well over a very wide range of lighting conditions. Bright sunlight provides an illuminance of over 100,000 lux, which falls to less than 200 when there are very heavy stormclouds, or twilight. On a clear, moonlit night we can function quite well in 0.25 lux, but struggle when there is only a quarter moon (0.01 lux) or it is overcast at night.

Our vision changes as it operates in lower light levels. In bright light, we rely almost entirely on the good colour vision of the cone cells in our retinae, for what is known as photopic vision. Much lower levels of illuminance, such as those of very dark overcast daytime, or moonlit night, start to bring in the rod cells for scotopic vision. Those rods offer no discrimination between colours, making scotopic vision almost entirely monochrome.

This explains why paintings which have really been created in very low light, and remain faithful to its effects, are largely monochrome, and why traditional methods place so much emphasis on tones. Even when your eyes have had the half hour necessary to become fully adapted to low lighting conditions, colours are not as intensely chromatic as they are in brighter light.

One of the many factors which contributed to increasing ability in the late nineteenth century to paint in high chroma throughout the year was the great improvement in indoor lighting which took place at the time. I will look at another more obvious factor in the next article on colour.

References

Wikipedia on Stanley Kubrick’s Barry Lyndon.

Mark Cousins (2017) The Story of Looking, Canongate. ISBN 978 1 78211 911 1.


Filed under: General, Life, Painting, Technology

Are you being pestered to upgrade to High Sierra?

Posted: 22 Nov 2017 02:23 AM PST

Some Mac users are being pestered by notifications to upgrade to High Sierra.

As I reported here just over a week ago, Apple installed this nudge using its pushed security and macOS patch service, on Macs which had not yet been upgraded to High Sierra. If you see this notification, it will reappear each week until you finally do upgrade, or it gets fed up some time in the New Year.

If you’d rather remove it, all you have to do is open the folder at /Library/Bundles, and trash the single bundle there named OSXNotification.bundle. As Apple created this folder specially for this bundle, there seems no harm in removing the entire Bundles folder.

(Thanks to Craig Grannell for alerting me to the fact that this notification has now activated itself.)


Filed under: Macs, Technology

Beware the bogus Symantec blog which will infect you with Proton D

Posted: 22 Nov 2017 01:21 AM PST

For the last few days, there has been a website posing as a Symantec security blog, at symantecblog[dot]com, which has been spreading malware to Macs.

Merely visiting the site does no harm, but the article there warns – completely falsely – about a new version of the old CoinThief malware, and offers a free download of a Symantec Malware Detector. That download, posing as an anti-malware tool, is of course the malware itself.

If you download Symantec Malware Detector and run it, the malware continues to pretend that it is a genuine Symantec product with a suitable splash screen, then requires admin authentication in a standard authentication dialog. Should you enter your admin password there, your Mac will have OSX.Proton.D installed on it, not an anti-malware product at all.

Currently, OSX.Proton.D is not detected by any of the bundled protection systems in macOS, such as XProtect. These only tackle Proton variants A and B, and because they are so specific, offer no protection against this Proton D variant.

Like the other members of the Proton malware family, the D variant captures sensitive information from your Mac, such as passwords, from keychains, 1Password vaults, and GPG.

Symantec Malware Detector, like other Proton malware, is signed using a currently valid developer certificate, belonging to Sverre Huseby (team identifier E224M7K47W). That certificate doesn’t appear to have been revoked yet, so will pass Gatekeeper’s checks.

Characteristic of a Proton D infection is the appearance of a new property list at /Library/LaunchAgents/com.apple.xpcd.plist, which shouldn’t be there at all, and hidden folders at /Library/.cachedir and /Library/.random, the latter containing the malware code. Fuller details are in Thomas Reed’s article for the Malwarebytes Labs.

Malwarebytes detects and removes the infection, Objective-See’s products will alert you to its presence, and Sqwarq’s DetectX also detects it reliably. Expect pushed security software updates from Apple in the next few hours or days to address this too.

(Thanks to @thomasreed, Patrick Wardle, and Phil Stokes for this important information.)


Filed under: Macs, Technology

The unified log in High Sierra 10.13.1

Posted: 21 Nov 2017 11:30 PM PST

High Sierra brings some changes to the unified log from Sierra 10.12.6, although as far as I can tell at present, these shouldn’t have any great impact on log use or analysis. As I have been unable to find any release note or other information about these from Apple, these may not be the only changes, but are those which I have been able to detect.

HighVolume

The most obvious change is that Apple has added a new folder to the main path to which ‘live’ log files are saved, /var/vb/diagnostics, named HighVolume. This is presumably intended to contain .tracev3 log files written when many messages are being written to the log over a short period of time.

I have not yet found any files in that folder, so I cannot assess that any further. Until I know more, I will omit any files saved to that folder from logarchives made by MakeLogarchive and Woodpile.

log stats

A new verb has been added to the log command, log stats, which provides some options for generating statistical summaries of existing logs. For full details, man log, at which point it’s worth noting that this updated man page still bears the original page date.

The options for log stats allow you to obtain information from either the current live logs (default), or using the --archive archivename option you can obtain them from the logarchive named archivename.

Other general options include:

  • --sort events [or] bytes : sorts results by events or by size, the default being size;
  • --count linennum [or] all : delivers results for only linenum lines, or all (default);
  • --style human [or] json : prints results in human-readable form (default), or in JSON format.

The final options determine which results are provided, of which you can select only one:

  • --overview gives an overview for the entire set of logs or logarchive,
  • --per-book gives figures for each log book,
  • --per-file gives them for each log file,
  • --sender sendername gives them for the sender named sendername,
  • --process processname gives them for the process named processname,
  • --predicate predicatespec gives them selected according to the supplied predicate predicatespec.

By log book Apple is referring to the major types of log, i.e. Persist, Special, and now HighVolume.

I have so far only tried this on a system which has not been collecting normal logd statistical summaries, and the commands take several seconds to complete even with few small log files. Worse, the results appear to be almost entirely spurious.

For example, figures given using the per-file option appear correct for the compressed file size, but the uncompressed sizes, start and end dates given for each file are identical, and appear correct for the whole log, not those individual files.

The figures given for events, activity, log messages, ttl, processes, and senders vary only slightly between each of the files, and cannot be correct: for example, the number of default log messages given for a log file which is 10,451,392 bytes in size when compressed is given as 3,811,510, and that for a log file which is 8,184 bytes when compressed is given as 3,811,710.

For the moment, I would not rely on any of the figures given by log stats until these issues have been addressed, which makes this new verb useless in its present form.

logd logs

Seeing the deficiencies in that Mac’s logd statistical summaries, I was concerned that maybe High Sierra has also stopped logd from producing those invaluable figures.

However, some Macs do appear to write them still, so I suspect this behaviour is dependent not on the version of macOS which is running, but on the model of Mac on which it is running. Statistics are missing from the logd logs on my old MacBook Air, but are still present in those logs written on my much newer iMac17,1.

I also wonder whether the log stats verb would normally extract statistics from the logd logs, just as Woodpile does, and only generates incorrect output when it doesn’t have the benefit of those. I’d be very interested to hear of the experience of others who have used log stats, or who have used Woodpile on High Sierra systems, please.

In summary, then, Apple appears to have made two changes to the unified log in High Sierra. The undocumented HighVolume folder hasn’t been seen to be used yet, and log stats, which is documented in the log man page, appears too flawed to use at present.


Filed under: Macs, Technology