Monthly Archives: December 2009

Tests

Experiment #2: A Hint

2 Comments

Here are the three source images:

The differences among them are obviously in the amount of noise that was added to the image. No noise was added to the first image – any noise there was in the original capture. 10% level “Uniform” noise was added to the second image in Photoshop. 20% “Uniform” noise was added to the third image in the same way.

The soft photograph was chosen to avoid masking the noise with a lot of other sharp detail – this image provides very smooth gradients from black to white, where noise is typically easier to detect. I also chose this image because it is nearly – but not quite – monochromatic. This meant that I could increase the effect of the noise by using color noise rather than limiting to monochromatic noise – and that the color noise would tend to be more visible against the nearly monochromatic background.

The original set of 6 jpgs includes two from each of the three versions shown here. For last-minute fun you could still visit the comment page and try to a) determine whether or not the differences are visible and b) which pairs of images are the least noisy, more noisy, and most noisy.

More information to come later this evening.

G Dan Mitchell is a California photographer and visual opportunist. His book, “California’s Fall Color: A Photographer’s Guide to Autumn in the Sierra” (Heyday Books) is available directly from him.

G Dan Mitchell: Blog | Bluesky | Mastodon | Substack Notes | Flickr | Email


All media © Copyright G Dan Mitchell and others as indicated. Any use requires advance permission from G Dan Mitchell.

Photographs: Northern California, Photographs: San Francisco, Photographs: Structures and Objects, Photographs: Urban/Street

Beneath the Bay Bridge

Leave a comment
Beneath the Bay Bridge

Beneath the Bay Bridge. San Francisco, California. September 16, 2009. © Copyright G Dan Mitchell – all rights reserved.

A pier beneath the west end of the San Francisco Oakland Bay Bridge with downtown San Francisco, California.

The light was a challenge in this photograph, but I found the dense and somewhat out of kilter lines and forms of the pier, bridge, and downtown buildings interesting. The photograph was made from one of the piers along the Embarcadero that is used as a parking lot – extending out into the Bay a bit it gave me a view back toward the City over and through the intervening structures.

This photograph is not in the public domain and may not be used on websites, blogs, or in other media without advance permission from G Dan Mitchell.

G Dan Mitchell Photography | Twitter | Friendfeed | Facebook | Facebook Fan Page | Email

keywords: san francisco, california, usa, travel, tourist, scenic, city, urban, downtown, skyline, buildings, embarcadero, plaza, oakland, bay, bridge, concrete, steel, pier, doors, pilings, water, birds, latter, flag, cable, freeway, highway, 80, deck, upper, lower, windows, fog, sky, urban, city, waterfront, architecture, stock

Tests

Experiment #2: What do you see?

25 Comments

In this experiment I invite you to view a sequence of six jpg files that include different versions of the same original photograph.

  1. All six images seen at the link began as the same original source file – a RAW file from a high quality full frame camera.
  2. Three versions of this file were created, with each altered in a particular way I won’t yet reveal in advance – let’s call them versions #1, #2, and #3.
  3. Each of the three versions was then duplicated – in other words two identical copies of version #1 were created, two identical copies of version #2 were created, and two identical copies of version #3 were created.
  4. The six files were randomly assigned slightly different file names so that in the end we have File A, File B, File C, File D, File E, and File F.
  5. The six images were then sequenced into a “slide show” version that automatically switches between them, but which also allows the viewer to select them individually.

The Experiment

After you view the linked files in your web browser as presented at the linked page I would like you to consider three questions:

  1. By viewing the files in your web browser as presented here are you able to perceive any visual differences between the files aside from the letters A-F indicating the different images?
  2. If you do perceive differences among them, to what would you attribute the visual difference?
  3. By viewing them in your web browser as presented, can you identify the pairs of identical images?

Click on this link to view the sequence of six presentations of the photograph. The sequence should open in a new window/tab when you click the link. Return here to report your results by adding a comment to this post. (Note: The link was briefly broken – apologies to those who got the missing page error. The problem should now be resolved. Direct URL: https://gdanmitchell.com/images/Experiment2/index.html )

Caveats and Warnings

  • I do not make any claims that this is a scientifically constructed experiment – let’s call it an informal investigation of a potentially interesting question.
  • If you view the comments of other participants before offering your own response you may be influenced by what they write. Therefore in the spirit of the experiment you should decide on your results before posting your response and before viewing the comment page – and resist the temptation to change your results after reading what others say.
  • The whole point of this exercise is to consider what you see when you look at these image in your web browser. If you want to participate, please limit your consideration of the images to viewing them in your browser on the linked page.
  • Feel free to look at the images as many times as you want or to switch among them manually. (You might want to mention the extent of your careful viewing in your comment.)
  • I’ll stipulate that if you download the files and carefully investigate them that you will possibly find differences whether you can see them or not. But don’t – this isn’t the point here. If you can’t resist doing this please keep your discoveries to yourself until the end. (I’ll also point out that I could do things in the files that might mislead you… ;-)
  • You are welcome to hold positive or negative opinions about the aesthetic quality of the photograph, but please keep those out of your response to this experiment.
  • I am not saying in advance what the difference are nor am I making any assumptions ahead of time about what the results will be. It is best if you do the same and keep an open mind.
  • I plan to reveal everything about the experiment in a day or two.

(This is the second in a series of visual experiments that I invite you to try. You can see the previous Experiment #1 and the followup post about the results.)

G Dan Mitchell is a California photographer and visual opportunist. His book, “California’s Fall Color: A Photographer’s Guide to Autumn in the Sierra” (Heyday Books) is available directly from him.

G Dan Mitchell: Blog | Bluesky | Mastodon | Substack Notes | Flickr | Email


All media © Copyright G Dan Mitchell and others as indicated. Any use requires advance permission from G Dan Mitchell.

Photographs: Northern California, Photographs: San Francisco, Photographs: Structures and Objects, Photographs: Urban/Street

Architectural Forms, San Francisco

Leave a comment
Architectural Forms, San Francisco

Architectural Forms, San Francisco. San Francisco, California. September 16, 2009. © Copyright G Dan Mitchell – all rights reserved.

Black and white photography of juxtaposed architectural forms in downtown San Francisco, California.

This is another “urban landscape” – this one obviously focusing on the juxtapositions of dark and light (both light/shadow and white/black), vertical and horizontal, the inclusion of a single curved shape at the upper right, and the effect of converging perspective lines. Although this looks like a photograph that more likely would have been shot from the tripod, this was actually done handheld while walking up Market Street not too far from the San Francisco Bay on a morning when Bay fog was just clearing away near the waterfront.

This photograph is not in the public domain and may not be used on websites, blogs, or in other media without advance permission from G Dan Mitchell.

G Dan Mitchell Photography | Twitter | Friendfeed | Facebook | Facebook Fan Page | Email

keywords: san francisco, california, usa, travel, tourist, scenic, city, urban, downtown, building, architecture, window, column, wall, railing, cement, concrete, stone, angle, converge, perspective, sky, black, white, monochrome, light, shadow, form, texture, morning, stock