Friday August 24, 2007

I'm on vacation this week and next, traveling with my wife by car through New Brunswick, Prince Edward Island, and Nova Scotia. I plan to post occasional photos as I'm able. This first one was taken in New Brunswick, not far from Mary's Point on the Bay of Fundy.

Thursday June 28, 2007

Sunday June 03, 2007

You probably know the human eye can handle a much wider range of light levels than can be captured on film or CCD. Where we can see detail in a scene with both shadows and a bright sky, a camera will either render the shadows as a deep, featureless black or blow out the sky to a featureless white. It often can't capture both the shadow and sky detail simultaneously.

Landscape photographers have traditionally used graduated neutral density filters to deal with this problem. However, using these filters can be a finicky process. Luckily, there is an easier and more effective way to accomplish the same end digitally by taking several exposures of the same scene and blending them with image processing software.

Before explaining how to do this, here are two test photos I took recently and the resulting blended image. The first image captures interior details, but at the expense of over-exposing the scene outside the window. The second image correctly exposes the outside scene, but at the expense of all interior detail. The final image shows what can be done with blending.

Interior correctly exposed, exterior over-exposed

Interior under-exposed, exterior correctly exposed

Final blended image showing both interior and exterior detail

One of my favorite photo websites, The Luminous Landscape, describes several approaches to digital blending using Photoshop. I describe below how to use approach #2 with the GIMP (free image manipulation software that probably does more than you'll ever need and costs nothing unlike Photoshop, which is outrageously expensive).

We will start with two images, Light and Dark, and produce a final, blended image.

1. Open Light in the GIMP.
2. Use "Open as Layer" to open Dark.
3. Create a Layer Mask for the Dark layer.
4. Copy Light. This is easily done by clicking on Light's thumbnail in the Layers window and typing CTRL C.
5. Select the Layer Mask by clicking on it once.
6. Paste Light. When you do this it will appear as a layer called "Floating Selection (Pasted Layer)" in the Layers window.
7. Now anchor the layer by clicking on the Anchor icon on the Layers window or using the pulldown menus. If all goes well, the Light image will now appear as the Dark image's layer mask.
8. Click once on the Layer Mask to select it and then use Filter->Blur to apply a gaussian blur with radius 40 to the layer mask.

With both layers visible, you should now have a blended image that you can flatten and write out in the format of your choice. Once you learn the above sequence it is actually quite easy to use. However, if you would like an even simpler method, consider using JD Smith's script-fu GIMP plug-in, available here. His script, exposure-blend, takes three images as input (light, dark, normal) and produces a blended result.

Sunday May 06, 2007

Monday April 02, 2007

While viewing birds with a telescope this weekend I decided to try some afocal imaging-- shooting photographs through a telescope (or binocular, or microscope) objective. This is also called digiscoping. I hand held the camera (with its focus set at infinity) so the results are not great, but you can see the promise of the technique. The birds were about 150 yards away and the magnification was about 75X. The first shot shows several great blue herons in a rookery in Westwood, MA. The second is a shot of a different tree in the same rookery. The two small birds are kingfishers. If you look closely in the bottom nest, you can see a great horned owl looking over its shoulder at the rightmost kingfisher.

Friday March 16, 2007

I've been waiting all season for this.

Monday March 05, 2007

Saturday December 16, 2006

Here are some shots from last weekend's quick visit to the Marin Headlands and to Point Reyes. Cloudy days, especially partly cloudy days, are often a lot better than very sunny days for landscape photography.

Golden Gate Bridge


Point Bonita Lighthouse, Marin Headlands


Point Bonita, Marin Headlands


Red-tailed Hawk hovering and hunting in the wind, Marin Headlands


Point Reyes, looking north with a 50 mph wind (and rain) at my back

Monday December 04, 2006

Sunday December 03, 2006

I bought my Apple Mac Book Pro back in March and have been waiting ever since for the opportunity to give Adobe $650 for a copy of Photoshop CS2 that supports the Intel Macs. Waiting and waiting.

I'm done waiting. I've taken another look at the GIMP, the popular free image editing tool, and it looks very good. Much more sophisticated than the simple tool I remember from years ago. It has support for Layers, for example. And more transforms than I'll ever use. It also supports, via a separate free plug-in, Canon RAW format. I installed both the base Gimp.app and the UFRaw plug-in. The installation was both simple and smooth. I'm still learning my way around the program, but it looks good so far.

Yesterday, I bought a copy of Beginning GIMP: From Novice to Professional by Akkana Peck, which looks like a good introduction to the GIMP. My only expenditure so far.

Friday November 17, 2006

I'm flying home to Providence from Tampa tomorrow morning now that Supercomputing '06 is over. I hope to blog today's two panels at some point--both were excellent. The first explored whether FPGAs might be the basis of the next big thing in HPC. The second was a very thoughtful and thought provoking discussion of the impact of multi-core processors on HPC.

In the meantime, a sunset shot to close this trip...

Thursday November 09, 2006

I had some medical appointments in downtown Boston yesterday and stopped at the charming Norman B. Levanthal park in the financial district, shown below. It is built on top of the Garage at Post Office Square, which according to their website has been called "The Garage Mahal" by the Wall Street Journal. On this visit, I opted for a free parking spot on the street, but can attest to the garage's implied opulence based on numerous other visits.

The fountain/sculpture in the foreground is almost certainly the work of artist Howard Ben Tre, who favors large chunks of cast glass and brass in various configurations. I like his work.

In the background, towards the right is the glass-enclosed Milk Street cafe, which was a cozy place to have a drink out of the rain and to take advantage of their free wireless connection.

Wednesday November 08, 2006

A little late, but one of my nephews celebrated Halloween as a bat. Too cute.

Saturday October 07, 2006

My wife and I visited Watch Hill, Rhode Island, on the same day we saw Sandy Hook, New Jersey. There's a certain symmetry in that since Sandy Hook is the northernmost point of New Jersey's shore, and Watch Hill is the southernmost point of Rhode Island's.

Watch Hill, Rhode Island (facing west)

We had dinner at the Olympia Tea Room and enjoyed both the ambience and the food. If you go, do try the Avondale Swan for dessert. Yum.

Thursday October 05, 2006

Sandy Hook is at the northern tip of New Jersey's shore, on the southern reaches of New York Harbor. It is home to the Sandy Hook Lighthouse (built 1764), historic Fort Hancock, an active Homeland Security installation, and several other organizations. It's also a great place to see birds that are migrating on the Atlantic Flyway. And it's very pretty.

Sandy Hook, New Jersey (looking north)


Sandy Hook, New Jersey (looking down)