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Welcome to Dijemeric Visualizations

Where photography and mathematics intersect with some photography, some math, some math of photography, and an occasional tutorial.

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Friday, May 28, 2010

Misterken Retires from the Lab

After 33 years at EBMUD doing lab rat work, I have decided it's time to do something else. So I'll hang up the lab coat I seldom wore, sling camera bag over my shoulder, and see what awaits.

Lab staff, as usual, gave a nice sendoff complete with sugary treats, a plaque proving I really existed for 33 years, a finely tuned roast by a master roaster, and an accomplished photographer to capture the final moments.  All-in-all a wonderful farewell. 

I think there was hidden meaning in this...but I'm unable to detect what it is!

Two cakes!  Plus a bowl of cherries!  Auspicious. 

Nirmela prepared a test of my knowledge of applied measurement theory.  

Note that while the mouse is visible it cannot be weighed on these scales and therefore does not exist. 
I passed the test. 

Linnea shows her talents as a Roasting Toastmaster
I'm feeling a bit warm.  

I yielded and agreed to all ten reasons given for my departure with a margin of error of +/- 100%.

Finally - the Cake!

Sunday, May 23, 2010

510Arts and the Ghost Roses Exhibit

It's official.  510Arts for the cities of Berkeley, Emeryville, Oakland, and Richmond has announced the annual Call for Submission to artists living in the 510 area code.  If you are an artist living in the 510 area code, check it out.

And if that weren't enough - the announcement includes my photo The Boiler Room shot at the former Sakai Brother's Rose Nursery in Richmond

AND the highly acclaimed and anticipated Ghost Roses exhibit featuring fine art photography by Ellen Gailing, Matt Matsuoka, Fletcher Oakes, and me will open September 14 and run through Nov 13, 2010 at the Richmond Art Center in Richmond, CA.

Watch here for more details.  

Thursday, May 20, 2010

By Popular Demand - High Dynamic Range Tutorial

This is a re-post of a popular tutorial on High Dynamic Range Photography, also called HDR. If HDR is new to you or you've heard of it but don't know exactly what it is or how to do it, watch this slide show.

High Dynamic Range Photography Explained - A Tutorial

Sunday, May 16, 2010

Ghost Roses

On the west side of Interstate 80 as it crosses through the cities of Richmond and El Cerrito are the remnants of a rose and carnation nursery. Forty abandoned greenhouses remain, some with roses still growing unattended. Family farmhouses (3), boiler rooms, and water tanks serve as reminders that this was once a farm.

The nursery began in 1906 with a single greenhouse  and grew to 40 greenhouses on 12 acres with the Sakai, Oishi, and Maida-Endo families.  No longer in production, roses still flourish in the abandoned greenhouses.  One greenhouse wears a cape of roses.  The carnations fare less well having shallower roots that cannot reach the water table during the dry season.

Soon, this will be only a memory except for a portion that the City of Richmond plans to retain, something like Vision for Restoration, the panorama shown below.

In September 2010, through the efforts of Susan Sharfman, Michele Seville, and Emily Anderson, an exhibit including my work and that of three other photographers will be on display together with an historical context provided by the National Park Service, the Cities of Richmond and El Cerrito, and Donna Graves an historian who has authored the report Historic Architectural Evaluation of the Sakai, Oishi, and Maida-Endo Nurseries of Richmond, CA available at  

More information will be available as plans for this exhibit are still in progress. 

Friday, May 14, 2010

A Dijemeric Tutorial - Printing At Costco

Back by popular demand, my Tutorial on Printing at Costco explains how to send your digital images to Costco and use of a profile to get the best results.

View slideshow

Wednesday, May 12, 2010

Strategies for Sampling in a Potato Warehouse

You rent a warehouse in the Mission District of San Francisco for the purpose of storing potatoes.  The storage space is not big with barely enough capacity to hold 5 tons, or 10,000 pounds of potatoes.  The owner of the warehouse is concerned that you might try and exceed that quantity and has placed a penalty clause in the contract if you do.  He also requires an annual inventory of the quantity of potatoes you are storing.  

You hire a high school student to weigh potatoes so you can determine how much is in a warehouse.  To estimate the weight of potatoes in the warehouse without paying the student to weigh each and every potato you've decided that you will have him make no more than 100 weighings, randomly selected.  Once the potatoes are sampled and weighed you will estimate the total weight by multiplying the average weight per gallon of potatoes times the total volume of potatoes in gallons in the warehouse (you know this because you have a calculator and are good at math).

To do this weighing, would it be better to have the student weigh lots of individual potatoes one at a time or weigh composites of several potatoes at a time in fewer collections of a gallon each?  And should you caution the student to take care in weighing?  Does it matter if you are just a little bit over the 10,000 pounds?  Will the weighings more likely show you are over if the weighings are precise?

The answers may not be immediately obvious and depend on at least three variables: 1) the precision of the student in taking the weights and volumes, 2) the difference between the actual 'true' weight of potatoes in the warehouse and the penalty threshold, and 3) whether the actual weight is above or below the threshold.  To test how these three variables can affect the outcome, I have developed A Monte Carlo Model for Sampling Potatoes or Anything Else.  Try it for yourself.

Enter the measurement precision (also known as percent relative standard deviation  or %RSD) in cell B3, the potato penalty threshold in cell B4,  and the expected true weight of potatoes in cell B5.  The outputs are in cells D7 (percentage hits exceeding the penalty threshold for weights of single potatoes) and E7 (percentage hits for collections of potatoes).

The small chart displays overall statistics of average, standard deviation (a measure of variability), RSD (a measure of precision), and number of Hits (number of times the given sampling method exceeds the penalty threshold).  In the example shown here, the averages for both methods exceed 10,000 pounds and the number of hits are 4800 for the single potato approach and 5500 for the collection of potato approach.  The true value was set at 10,000 and precision at 50% (i.e., sloppy technique) for the default settings. 

The long chart displays the first ten samplings of the student under the two different sampling methods and can be used as a check to track his performance.

Try entering different values for RSD, threshold, and true weight and see what you get.  For example, if the student is sloppy does it make any difference if the threshold is above or below the true value?  If the student is very precise can you get closer to the threshold without a penalty?  And don't be timid about the actual weight of potatoes.  You might try putting in more than 10,000 pounds and see if you can avoid the penalty!

Tuesday, May 04, 2010

The Drunkard's Walk

Random events can be misleading.  Flip a coin.  It has a 50% chance of landing heads and 50% tails.  Now suppose it has landed heads 10 times in a row.  What are the chances it will land heads up on the next toss?  If it is truly an unbiased coin, the odds for a heads up will be 50%.  Past events have no effect on future events.  But what are the odds that a coin will land heads up ten times in a row? 

The chart below shows a plot generated from a random number generation program, Drunkard's Walk.  Try running the program Drunkard's Walk yourself and see what kind of trends you can generate from a random process. Enter any number in cell B8 (Count).  Press return.  Each plotted point is the sum of the previous plotted point plus the random assignment of a one or a minus one.  Are there trends?  Does it always look random?

Monday, May 03, 2010

Twenty Seven Years of Rainfall Records

Rainfall records on a home rain gauge measuring the rainfall in Richmond CA on the Wildcat Canyon ridge since 1982.  

Rainfall Records by Year

Sunday, May 02, 2010

Dijemry for March 2010

Somehow March got skipped, so for April I'll start with the Berkeley Camera Club's March field trip to the Delta and towns of Locke, Walnut Grove, Isleton, and Rio Vista.  First stop, Al the Wop's
 in Richmond still flourishes with roses at the former Sakai Brothers Rose Company.  I've made a couple more visits recently with postings at and

And while on the subject of roses, stay tuned for an exhibit coming up in September.  It's still in the planning stages, but when I have more information like dates and location, I'll be sure and let you know.  

We've had some nice wet days recently and incredible skies.  Just the kind of atmospherics photographers like, which you can see why in SD1 Views on a Cloudy Day at Lunchtime

And with rains come wildflowers.  I drove to Mount Diablo a bit early for the big blooms, but was not disappointed with what was flowering.  See some wildflowers, barns, and the car I drove at

I'm sure May will bring even more wildflowers, so until then 

Keep the light focused.

Documenting with Video - Controlling Invasive Species

At the risk of alienating the few loyal visitors Dijemeric Visualizations, where math meets photography, the next few postings will be of a gardening topic using videos shot with a Pentax K7 DSLR.  My backyard hosts a number of oak and bay trees along with an understory of native plants such as Sword Ferns, Trillium spp, wild rose, Yerba Buena mint, and others I have not yet identified.  There are also invasive weedy species which if allowed to grow eventually dominate and displace the natives.

All plants, native or invasive, have growth and reproductive strategies.  The secret in bringing the invasive plants under control is to take advantage of the differences in those strategies.  The immediate subject is Witchgrass.  It is an annual that grows to a height of about two feet prior to setting seeds.  The strategy is to cut the Witchgrass at a height low enough to remove the seed heads before they ripen but low enough to leave the shorter native plants, such as the Trilliums.