A Histogram Analysis of Muddy TCS Photos

Editor,

While viewing the latest issue of The Citizen Scientist (3 June 2005), I noticed that some of the images were not up to their usual high quality. I thought that a little investigation would be in order, possibly to get the problem fixed or at least to avoid it the problem in the future.

The Mount Kilimanjaro picture looks blotchy and lacks the full range of colors. Using an image editing program I took a look at the histogram of the luminosity values in the image.

There are six sharp peaks in the luminosity values, with only a few intermediate value pixels (Fig. 1). By comparison, the histogram (Fig. 2) of Forrest's poison ivy picture (Fig. 3) has rounded peaks and lots of intermediate value pixels. The small number of sharp peaks would explain the appearance of the Kilimanjaro picture, but how did it get that way? If we know how then it might be possible to avoid the problem in the future. What I suspect is that the number of bits per pixel was reduced at some point, probably in an effort to reduce the amount of data in the image. In an attempt to reproduce the effect I took Forrest's ivy picture and reduced the number of bits per pixel from 24 to 4 and then reconverted the image to jpeg format.

This image now looks a lot like the Kilimanjaro picture, and its histogram is similar (Fig. 4). This type of processing is likely what caused the image to look like it does. It is also possible that the image was originally scanned that way or taken with a low resolution digital camera. One thing about reducing the bits per pixel is that you don't get the reduction in file size that you would expect. I reduced the bits per pixel from 24 to 4 which should have given a 6 to 1 reduction in file size. The reduced file was only one half the size of the original. This is probably due to the way the jpeg compression algorithm works.

Note: There is some more investigation that could be done here to see if other compression algorithms work better or if there are other settings of the jpeg algorithm that would give a smaller file. In terms of viewability I would have preferred that the image size be reduced rather than the bits per pixel to achieve the reduction in file size.

Jim Hannon

Great letter and a nice analysis, Jim. The poison ivy photo was simply reduced from high to low resolution. Your analysis shows that this had little or no effect on the color range. This suggests that the Kilimanjaro photo was made on a very hazy day or with a camera having low resolution and/or inferior color response. Digital photography is so utterly fascinating, and so important to citizen science, that it would be good to publish in TCS a serious article that explores the topic you have raised. Anyone care to submit such a piece? Editor.

Reacting to an Asteroid Headed Our Way

Editor,

The article on Asteroid 2029 MN4 was very interesting, especially the NASA graphics showing the orbits of the asteroid into the future including its close passage on April 13 of the year 2029 ("Earth's 2029 Encounter with Asteroid 2004 MN4," The Citizen Scientist, 20 May 2005).

I contacted the NASA web site to ask whether NASA has calculated a date at which, given a certain impact probability, it should launch a mission to deflect the asteroid, and whether they are planning any deflection missions to study how they might be carried out should one be necessary? That is to say, if its impact probability increases to a dangerous point at what date should we launch an interceptor mission to try and deflect the asteroid.

Donald Yeomans, the manager of the NASA Near Earth Object Program Office said, "Good question. There is no policy or impact probability that would prompt a deflection mission. Our policy makers have not yet assigned an agency responsibility for such a mission. However, there have been some very preliminary plans for when and how such a mission would have to be initiated."

In 1990 the American Institute of Aeronautics and Astronautics (AIAA), under the leadership of Dr. Edward Tagliaferri, issued a position paper calling for studies on how to increase the detection of potentially dangerous asteroids and what to do if one threatened to collide with the Earth. NASA reported on these studies in 1992, which resulted in the establishment of the program Mr. Yeomans heads.But apparently little has been done by the government to give an agency responsibility for preventing such a catastrophe should a dangerous asteroid be found.

Of course, some may say, what's the hurry, we have 25 years to deflect 2004 MN4 should it ever need to be deflected. But should it need to be deflected, the sooner you do it the easier it would be. A little nudge now for example, would result in large miss in 2029. If the probability of collision increases with time the effort required to deflect it also increases. The point is some agency should be charged with planning for a deflection mission should it be required. The planning should occur now not later if the chances of success are to maximized. It would also be very useful to conduct some practice intercepts with whatever deflection technology is chosen, e.g.., landing a rocket on the asteroid, explosives, etc., to see what works and what does not.

While asteroid 2004 MN4 might remain harmless to us for the foreseeable future, we might discover a more pernicious one tomorrow with a much smaller window for deflection.

Johan Benson

Pro-Am Revolution Confusion

Editor,

Regarding the book about Pro-Am collaboration ("Reflecting on "The Pro-Am Revolution," TCS, 3 June 2005), I think it is mainly for astronomy. However, the book seems to think that there is indeed Pro-Am collaboration in all professions. Does this mean that an intern in a medical profession is an amateur? It states that a therapist is an amateur.

It sounds like the author wanted a book that would appeal to all readers and missed the boat. To say the least, I am confused.

As Always,

Anna Hillier

More on the Pro-Am Revolution

Editor,

I downloaded and printed "The Pro-Am Revolution." My overall impressions were that the book was a bit hard to read. It seems like there was a lot of verbiage to say things. I got the impression that the authors do not know a lot about any of the Pro-Am activities that they discussed. Some of the activities were a bit of a stretch for making a Pro or Amateur distinction (gardening, mountain climber?).

One has to do a bit of translation, as the book was written with a British point of view. Overall the authors are right. The internet has allowed these kinds of activities to exist and flourish.

Lets look at some details. Gardening covers a lot of different activities. It seems like a professional gardener and an amateur gardener do entirely different things. At least around here, gardening means growing flowers and vegetables. If I sell some of the things I grow at a farmers market, am I a professional gardener?

The book discusses support for Pro-Am activities There may not be anything like it in Britain, but in the US there are Master Gardener Programs. Amateurs are trained to help gardeners with questions about their gardens. My mother got certified as a master gardener through the Missouri Botanical Gardens.

The idea that DIY has an effect on the economy has even caught the attention of Fortune Magazine. A magazine devoted to DIY is http://www.makezine.com/.

Jim Hannon

Einstein's Tea Leaves

Editor,

In a tribute to Einstein on the 100th anniversary of his birth, Banesh Hoffman tells how he first met Einstein in 1935. As a young physicist he had made some relativistic calculations and a friend suggested he go to see Einstein to ask his opinion of his work. Hoffman thought the idea preposterous. "I was far to scared. My friend almost had to push me to the door of Einstein's office. I knocked timidly, and Einstein called out the single word "come" with a friendly, rising inflection. I entered in fear and trembling, and there was Einstein sitting sitting in a comfortable chair, sloppily dressed, his hair awry, a pipe in his mouth, and a sheaf of calculations on his lap. I managed to tell him why I had come. He must have seen my nervousness. He smiled and gently asked me to put my equations on the blackboard, and then came these words, which I shall always remember: "Please go slowly. I do not understand things quickly." This from Einstein! At once, as if by magic, all my fears left me." ("Albert Einstein: Historical and Cultural Perspectives, The Centennial Symposium in Jerusalem," Princeton University Press, 1982, pp. 401-402. The Symposium was held in March 1979.)

Hoffman subsequently collaborated with Einstein and Leopold Infeld on a paper.

Later in his tribute Hoffman continued: "I now want to tell about a small dinner party that I was invited to at the (Einstein) house on Mercer street (Princeton, New Jersey).... While tea was being served- from a teapot and not via teabags- Einstein pointed out that when one stirred one's tea, the tea leaves congregated at the middle of the bottom of the tea cup and not the perimeter, where one might expect them to to congregate. He asked me if I knew why. I knew Einstein had published an explanation, but unfortunately, I could not recall the details. Perhaps, though, that was for the best, because Einstein found great pleasure in explaining it to me in detail, including its link to the meandering of rivers."

Unfortunately, Hoffman did not include Einstein's explanation in his talk. Perhaps you might publish this and see whether some of our members can come up with a suitable explanation.

Sincerely,

Johan Benson.

Readers, can you explain this mystery? Please send your replies to "Backscatter" with "Einstein's Tea Leaves" in the subject line. Editor.

Letters to "Backscatter" are welcome. Letters are subject to light editing to correct punctuation, spelling and grammar. By placing "Backscatter" in the subject line, you give us permission to consider publishing your letter. Send your letter to Backscatter.