Digital Photo Processes

-- Introduction -- Lens & image -- A/D conversion -- Lumix & Leica --  Sharpness -- CCD noise1 -- CCD noise2 -- 5 years later -- 

Introduction

Photography has been of life long interest to me. I started out in my high school years with a relatively small bellows camera, turned my bedroom into a darkroom when needed, developed black and white film and printed enlargements. Over time I graduated to a Rolleiflex and then to a Pentax SLR with multiple lenses. My camera bag grew ever larger and became too heavy. I started to take along only the essentials and began to simplify. I was willing to sacrifice features and even some performance for size and weight. I actually enjoyed the challenge to use the equipment limitations to photographic advantage if unavoidable.

Eventually my cameras became smaller. On business trips, vacations, outings and family events I mostly carried with me one of the various small Olympus Stylus 35mm cameras. I took slides and gave slide shows. Now I have boxes full of them. Little got printed. One of these days I may put a printed collection together to pass on to my children and grandchildren. 

The advent of digital photography rekindled my interest in capturing the essence of a moment. The darkroom was now on the computer. Cameras could be small, picture taking inexpensive and I could have easy control over every step of the process.

So the Olympus XA2 film camera was replaced by its digital version and then I drifted to Canon A610, A540 and A700 models. In my search I also acquired an Olympus C-5050 and a Nikon E8400.

My favorites these days are the Panasonic Lumix FZ50 and the Lumix LX2. One is large and therefore only gets taken when its manual zoom range of 35mm to 420mm, or the electronic view finder, or an external flash, or its swiveling LCD might be important. The LX2 with its relatively small size and wide range of capabilities, though, comes along even when there is no specific plan to take pictures. 

Both cameras have "Leica" lenses and can output RAW picture data files. Their CCD sensors, though, are small. While this makes the small physical size of the optics possible, it also limits the ultimate image quality due to noise and how it has been processed in the camera. 

In these web pages I will show what I investigated and learned about noise and artifacts in digital photo processing. I pursued this specifically with the LX2 in mind because I love this little camera and wanted to understand its practical limitations in different lighting situations. There are also the Leica branded D-Lux 3 and V-Lux 1 models. They use camera firmware which is different from the related Panasonic models. It is not clear whether this affects the ultimate image quality that can be obtained from either brand, assuming that their optics meet identical specifications.    

Panasonic Lumix DMC-FZ50 and DMC-LX2. 
Note the bore-sight that I glued to the LX2 for finding the center of a scene when the LCD is difficult to see due to bright light or when the scene changes too quickly to track with the LCD. A similar, longer finder could be slipped into the FZ50 hot-shoe for tracking fast moving object at long telephoto extensions.

Photo processing stages

The light from a photographic scene is captured by the camera and converted into digital data in Stage 1. The scene can then be viewed on on the camera display, be sent to a printer for a paper copy, or be sent to a computer for storage. There, in Stage 2, the picture data can be further manipulated using specialized software to yield optimum image quality on a computer monitor. The data can also be prepared for optimum print quality depending on printer, ink and paper in Stage 3. 

The information flow from the scene to the final picture output goes through bottle necks at each stage. Information is distorted on this path, some is lost, different artifacts and noise are added. I am particularly interested in the front end, the camera, and what it adds and removes from the original photon flux input while it is converted to a pixel data output.

-- Introduction -- Lens & image -- A/D conversion -- Lumix & Leica --  Sharpness -- CCD noise1 -- CCD noise2 -- 5 years later -- 

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CAUTION: The content of the Digital Photo Processing pages may change without notice as I learn new things or find better descriptions. See the What's new page.  Photography is a hobby for me and I am not selling anyone's products, though I may be very specific about certain one's. You find here descriptions and experiments that helped me to understand more about digital photography. Maybe some of it is useful to you. My interest is specifically in small and easily portable cameras that also provide full manual control. Cameras, as every product of engineering, are designed with trade-offs. Understanding those, they sometimes can be worked around by changing techniques or they can be used creatively. The camera is just a tool, after all. Write to me only if you have something constructive to add and then use a recognizable email Subject line. I get hundreds of emails per day and 97% of them are junk that I flush out. The remainder deals with loudspeaker issues. Just as loudspeakers are ultimately about auditory perception, so are cameras about visual perception. Both fascinate me.