Thursday, December 20, 2018

Now Available - dans les Paddocks ~ le Mans Classic ~ 2016

dans les Paddocks ~ le Mans Classic ~ 2016

I am happy to announce that a book project of over 100 images is now available.  The work is printed in classic black and white.  I chose monochrome to pay honor to the time and style of reportage many of the automobiles have come from.

Aston Martin ~ le Mans Classic ~ 2016

Saturday, December 08, 2018

A little something called "SuperResolution"...

A friend recently picked up a Nikon D850 and more recently a new Fuji GFX 50R.  Both are very high resolution cameras.  In my case, the highest resolution camera in the closet is a 24mpixel Sony A6000.  Beginning to feel a little "behind the curve" in the Mpixel Race (whatever that is) I wondered how close I could come to 50mpixel sensor output given my current tool set.

Several years ago I saved a link to an article that described a process for creating very high resolution photographs.   I found that recipe after having written about how to generate high resolution images from a single base image.  This blog entry combines the two techniques, and adds a few things that I've learned along the way (which I will Note: in the text below).

Base setup -
  • Sony NEX-5T set to jpg output (to streamline the stack blend processing)
  • Lenses
    • Sigma 19mm EX DN E
    • Nikon Nikkor 50mm f/1.8 AiS
    • Nikon Nikkor 85mm f/1.8 K pre-Ai
  • Camera handheld
  • Multiple exposures shot using the "S" fastest continuous shutter release function
    • Shot 20 to 30 images of each subject that would next be used to create an image stack
  • Follow the "SuperResolution" recipe (with two important Notes and one Observation) using
    • Hugin to align the image stack
    • Gimp (v2.8) to perform a linear 2x "cubic" uprez from approx 4900 pixels (native Sony NEX-5T file size) to 9500pixels
    • Gimp (v2.8) to blend the layered image stack
    • Gimp (v2.8) to apply a 2 pixel unsharp mask
In the following side by side comparisons, along the left hand side I have labeled from "File Viewed at 100%" to "File Viewed at 400%".  This applies in all three comparison cases to the left hand column only and represents the base image at its native resolution viewed at the indicated enlargements.  The right hand indications of "File Viewed at 50%" thru "File Viewed at 200%" apply in all three cases to right three image columns.  These three columns represent the output of various processing techniques I used to explore the idea of "superresolution".

Setup One - Nikon Nikkor 50mm f/1.8 Ai set at f/8

Super Resolution Investigation ~ Base Image
Scene Setup

Super Resolution Investigation ~ Comparisons

Setup Two - Nikon Nikkor 85mm f/1.8 K pre-Ai set at f/1.8

Super Resolution Investigation ~ Base Image
Scene Setup

Super Resolution Investigation ~ Comparisons

Setup Three - Sigma 19mm f/2.8 EX DN E set at f/4

Super Resolution Investigation ~ Base Image
Scene Setup

Super Resolution Investigation ~ Comparisons

Comments -

Regarding the optics, all three lenses performed very well, indeed.  They are sharp and contrasty in the base image.  Printing at 300dpi using the native 16mpixel sensor resolution of the Sony NEX-5T will easily generate a 17inch on the long dimension high resolution image.

As for the "superresolution" techniques, here is what I have thus far experienced.

My early understanding of how "cubic" up-rez works was insufficient.  Up-rez'ing an image at 150dpi or 300dpi will yield jagged edge transitions and will amplify "noise" across an image field. 

Note: What I've learned is that by increasing the sample rate of the "cubic" filter that the output up-rez'd image will contain fewer artifacts.  In clear terms - to perform a 2x up-rez requires, minimally, a 600dpi filter sample rate.  This is fundamental to understanding how to retain the most image quality when performing an up-rez. 

For this comparison I set the "cubic" filter sample rate to 1200dpi.

Using the Gimp's "cubic" Image Scale function quickly generates a 9500pixel file from the base 4900+pixel image.  No new information is added, of course.  Image problems (shake, mis-focus, etc) and sensor "noise" are amplified.  Following my early attempts at understanding "superresolution", this approach still has some promise.  Compared with the following two "superresolution" examples that follow, the simple "cubic" up-rez technique is somewhat lacking.

Looking at the blended image stack examples I see the results can be pretty interesting.  The very first thing I see is a dramatic drop in sensor "noise".  The images are much smoother than even the original base image.  In fact, blending just two images produces a very useful reduction in noise, even in a non-up-rez'd image, that this technique is worth utilizing.

The second thing I see is that stacked images do indeed appear to add information to the resultant image.  This is much like what we expect out of the "superresolution" functions in some Olympus and Sony mirrorless cameras where, in those cases, they "wiggle" the sensor electronically.  For the handheld technique, this is a very nice finding.

The technique of image stacking wasn't as straightforward as described in the recipe.  My first attempts were actually rather soft.  On close inspection I found that the Hugin "aligned" image output was not really "aligned."  The images were all too often many pixels mis-aligned, but only in the "y" dimension.  The "x" dimension seemed to be correctly positioned.  There is something I don't yet understand about the Hugin image stack output and how to import them correctly aligned into the Gimp.

Note: To achieve correct image stack alignment I chose a scene segment with clear dark to light transitions (like a raindrop or door keyhole or a piece of paper with writing) and set the "view" to 400% so that I could see every pixel magnified.  Using the base image (the image at the bottom of the stack) as the reference I worked with each layer, one at a time (turning off the visibility to all the other layers and by setting the "opacity" to 50% so I could see both the layered image and the base image). Then I used the keyboard arrows to move the layered image to set the exact alignment.  It was time consuming but yielded, obviously, the best results.

Observation: The recipe calls for a minimum of 20 images stacked and blended to get the most information.  In my case, I found that as few as 5 layers above a base image can yield outstanding results.  Perhaps my process technique isn't as accurate as it could be, but I can't see any "improvement" in the amount of information an image stack gives by going beyond those first 5 layers.

The last item in the recipe was the strong suggestion that a 2 pixel unsharp mask sharpen function be applied to the up-rez'd blended "superresolution" image stack.  To my eyes the results are quite impressive.  It appears, at first glance, as if a 300dpi 30inch print can be made while retaining all the native blended layer file resolution of the up-rez'd image stacked file.

It appears that my output is similar to the recipe examples.  Before declaring victory and moving on to another area of investigation I needed to compare my results, not only with the original "superresolution" recipe, but with the output of the latest generation of high resolution cameras.  Looking thru Flickr for Fuji GFX full resolution images I have come to realize that the handheld "superresolution" technique produces a different "look."  The native GFX file resolution is clearly superior to the approach being explored here.  Have I missed something in my own process?  Or is this just the way things are?

While clearly superior to native resolution base image output, using the handheld "superresolution" technique produces an image that reminds me of the soft, gentle tonal transitions I see in old contact print large format film. That is, the "feeling" of the image is that of light gently scattering through the gelatin surface coatings of traditional 20th century print papers. 

Saturday, December 01, 2018

Process ~ when it seems to work

Looking back over the past two years I see that a lot has changed in my understanding of the craft of photography.  I've looked as deeply as I could (without access to a full optical lab) at the subject of lenses, resolution, and what really happens when we talk about resolution and "sharpness".

I was prodded into action by a couple of articles on The Online Photographer's blog about how to make "good" black and white images from digital files.  The outcome of that was I rediscovered how much I enjoy making monochrome images.  As a bonus it seems to me that my current output has become "sharper" and "smoother" than my earlier 4x5inch and 8x10inch enlargements and contact prints.

Which leads me to a short story about the path I've taken in transitioning from large format film to APS-C digital.

Uffizi Gallery ~ Florence, Italy 2018

The thing that kicked me into digital was it's ease of access and immediacy.  I could see something, snap a photo of it, and review the results before I continued on my way.   The change certainly was not because digital was as sharp as large format film.  It wasn't.

When I started into digital I acquired a Canon 40D (later a 50D, a 7D, and a 5D MkII) and two lenses, a 24-105L and a 10-22mm EF-S.  I paid a lot for all this equipment so I was "all in" as they say.

Looking back I'm shocked at my early digital work.  In a small size the images are merely OK.  But comparing the original files against my current output I can't believe I hadn't chucked the whole plot into the ocean and returned to film.  The Canon sensors and lenses, while famed and widely lauded, are "soft".  The original files are nearly unusable.  I can't stand to "pixel peep" them.

Thinking I might shoot a bit of video I started picking up old Nikon Nikkor manual focus lenses.  They are widely available and can be had for little money.  I went with Nikon because Canon's old R/FL/FD mount lenses would not fit on Canon EOS without serious modification.

Uffizi Gallery ~ Florence, Italy 2018

With the Nikkor lenses all I needed was a simple adapter.  But manually focusing, even with AF confirmation chips in the adapters, was a hit and miss operation.  For this one reason I never could see how much sharper than Canon zooms a good fixed focal length lens really is.

One of the first things I did after buying a Sony A6000 was to mount one of my Nikkors on the camera and see how sharp the system was.  I was shocked by what I saw.  The APS-C sensored images were demonstrably sharper than anything I ever saw out of the Canon system.

Knowing what resolution was possible and wanting a bit of auto focus, I purchased a trio of Sigma Art DN lenses, tested them, found them to be as sharp as my Nikkors.  Back when I owned Canon cameras Sigma was still known as a low cost, low quality aftermarket supplier.  Over the years Sigma's reputation changed and some of that is due to the quality of the Art DN series.

Now I have a choice between using the old manual focus Nikkors and newer AF capable small lenses.  I find that around town and when I can relax and take my time I like using the Nikkors.  When my wife and I are traveling the Sigma lenses are just about perfect.

Accedemia ~ Florence, Italy 2018

On this end of the long road of experience I find that coupling high quality imaging with a better understanding of how to make a "luminous" black and white image that something startling to me is possible.  When I compare my old 8x10inch film contact prints with a digital print, the digital image in many ways "looks" better.  When I compare a 20x24inch enlarge 4x5 image to a similarly sized digital image I see the very same thing.   The digital image in many ways "looks" better.

While there is so much more I could say about all this (I have obviously skimmed over many important details), the bottom line is: The tiny, very lightweight Sony APS-C mirrorless cameras produce images at least the equal in terms of quality as any high quality large format film camera I ever hauled through the world.