Exposition (2 of 2)

This is the poster (designed by Ria van der Ploeg) for an overview exhibition of four friends with a somewhat comparable “pure” or classical style of photography from our local photo club:

The exhibition will be opened on Sunday, January 29th 2012 by our photography mentor, Hans Zoete. The exhibition is at an art gallery in Eindhoven and lasts 6 weeks. The exhibition website (http://www.puur-2012.nl) is in Dutch but largely consists of images.

Posted in Peter, Photos | Tagged , , , , | Leave a comment

Exposition (1 of 2)

This is the poster (made by Ariejan van Twisk) for the yearly exposition of my local photography club “Fotogroep Waalre”. The poster shows a picture by Aad Schoenmaker that I really like. Although the picture may look like it was created in Photoshop, it is essentially an as-taken photo. I deliberately won’t explain how Aad managed to get himself warped into this cyberzone, and leave it to you to guess (or ask Aad).

Posted in Temporary | 2 Comments

Fuji’s Organic Sensor Technology

In 2009, Fujifilm was granted a patent on an organic layer to improve CMOS image sensor performance. The thin organic layer converts incoming light to electrical charge (like a solar cell) that is then detected by more or less conventional CMOS image sensor circuitry.

Fujifilm’s “organic sensor” technology started to receive attention recently due to speculation that it would be featured in a future high-end compact camera (expected in early 2012; possibly called the “LX10“). This camera is expected to have an interchangeable lens and target the same market as the highly successful Fujifilm X100.

Although Fujifilm has not confirmed the use of their organic conversion layer in the forthcoming camera, a Fujifilm executive claimed that the interchangeable lens camera (possibly with an APS-C sized sensor) will outperform the current generation of full-frame sensors in terms of noise.

The technology

Fuji sensor with "panchomatic" organic layer

Fuji sensor with "panchromatic" organic layer (taken from Fuji's 2009 white paper)

A color sensor using this technology uses a conventional color filter array to make individual pixels sensitive to green, red and blue light. In a 2009 white paper, Fuji states that the layer is insensitive to infrared light. Therefore no IR absorption filter is needed, which is in itself a minor benefit.

The organic layer is labeled “Panchromatic Photoelectric Conversion Layer” in the above diagram by Fuji. The layer is 0.5 μm thick, and converts almost all visible light to an electrical charge (electrons and holes). The organic layer, which closely resembles a solar cell technology, is sandwiched between a negatively charged transparent electrode (like in LCDs) and an array of positively charged square “Pixel Electrodes” that form the actual imaging pixels. The latter are not transparent.

Electron microscope image of the upper surface of an array of 3 μm (aka um) pixel electrodes. The small circle within (below) each square the metal conductor that connects each pixel electrode to the transistors below.

In the 2009 prototype the pixels are spaced 3 μm apart. This would result in a resolution of roughly 40 MPixels for an APS-C size sensor or 22 MPixels for a Four-Thirds size sensor. Due to the gaps between the pixel electrodes, 85% of the surface area is used to capture charge. The possible loss of 15% of the incoming light can probably be neglected anyway, but these gaps could be further reduced if Fuji wants to and may not play any measurable role at all if the free electrons generated above the gaps reach the pixel electrodes anyway due to the applied electric field.

So a key benefit of this technology is that it is efficient compared to alternative ways to make arrays of relatively small pixels. With small pixels in a conventional CMOS sensor, the gaps between pixels (or the inverse “fill factor”) becomes a problem, especially because the wiring needing to access the pixels lies on the upper (outside) layers of the sensor. Backside illumination (BSI) addresses the latter by grind down the chip and illuminating the sensor from the back.

Fuji stresses that their sensor doesn’t need a micro lens array to funnel the light to the pixels. Apart from a reduction in component count, this avoids color errors at the edges of the sensor. This occurs with small pixels due to crosstalk between the color channels when light hits the sensor at an extreme angle.

The Benefits

One key benefit of this sensor technology should be its sensitivity to light: Fuji measured a quantum efficiency of 65% in 2009 (for green light at 550 nm) but stated that this can be improved by adding anti-reflection coatings. The quantum efficiency figure seems competitive compared to relatively expensive backside-illuminated sensors as used in recent high-end sensors with small pixel dimensions (such as the Nikon P-100, Canon S100, iPhone 4 and iPhone 4s).

This translates to a slight sensitivity gain – and would behave like removing a very light gray neutral-density filter. Using the available data, I am unable to calculate how big this improvement is expressed in ISO. Note that the prototype sensor described in 2009 will obviously differ from Fuji’s current technology anyway.

A more interesting question is what impact the technology change has on dynamic range. The ability to funnel more light to the sensor helps sensitivity and noise. But dynamic range depends on the ratio between the maximum amount of charge the pixel can hold (at saturation) compared to the noise level. Given the high expectations set by Fuji for the 2012 camera, the benefits of the organic layer must somehow translate to a dynamic range improvement (as differences in quantum efficiency between modern sensors tend to be limited).

Impact

It is a bit early to speculate on the impact of an unannounced camera of only leaked images seem to exist. Especially when we can only guess whether it utilizes Fuji’s organic photoelectric conversion layer. But what would happen if the technology delivers? In particular, would it really close the image quality gap between say full frame and APS-C sensors?

The key question for strategists is thus whether an organic layer would improve all sensor sizes and sensor resolutions to the same degree. If so, it could simply improve the quality level of what could be manufactured, but doesn’t change the landscape of Four-Thirds versus APS-C versus Full Frame versus Medium Format sensors. Fuji’s white paper starts off with

We proposed a new CMOS image sensor with a thin overlaid panchromatic organic photoelectric conversion layer as the best candidate for sensors with reduced pixel size.

and its title also mentions reduces pixel size as the highlight of this technology.

This suggests that the organic layer helps increase the design of high-resolution sensors regardless of their size, by improving their light gathering efficiency. This implies improved performance of tiny compact camera sensors with mere 1 μm pixels, and would provide an alternative to the cumbersome back-side illumination technology used in some compact cameras and camera phones.

It could also pave the way for 20 MPixel Four-Thirds sensors and 40 Mpixel APS-C sensors, and 80 MPixel full-frame sensors. Such (relatively speaking) extreme resolutions when using 3 μm pixels might be overkill for many lenses, but would indirectly increase image sharpness by promoting cameras designed without an anti-aliasing filter. Such an AA filter softens the image to get rid of details that are too fine to be resolved. But in doing so, AA filters also blur the finest details which the sensor can capture (in essence an anti-aliasing filter is a sheet of very finely frosted glass).

Because extreme resolution is not always needed and is sometimes even useless, a high-end camera could conceivably provided modes whereby the full pixel resolution can be downscaled within the camera. For example a full-frame camera 80 MPixel camera might normally record at 40, 20 or 10 MPixel resolution. But can be set to resolve in 80 MPixels if the user wants this. Current Canon SLRs already have a similar resolution scaling feature that Canon calls SRAW, but the option is not used very much because it gives loss of detail without shrinking the file size much. Note however that this route should give fine image quality, but likely costs more energy than the equivalent lower resolution sensor (more samples to digitize, more digital operations).

[ last modification: 26-Nov-2011 ]

Posted in Photo Technology | Tagged , , , | 3 Comments

Fotogroep Waalre 8-Jun-11

2011-Rotterdam-024 (100 ISO, 135mm, f/7.1, 1/400)

This composition is essentially about diagonal lines in modern architecture.

The Toren op Zuid (aka KPN Gebouw) by Renzo Piano has a façade with an overhang of 6°. The single external pole is for the required extra support. The foreground on the left is part of the nearby Erasmus Bridge.

2011-Rotterdam-015. Click to view larger (100 ISO, 70mm, f/10, 1/400)

Nearby there is a new high-rise residential building (“New Orleans”) and cranes for the next high-rise project (“De Stad Rotterdam”). Some viewers complained about the distracting cloud “coming out of” the building. The Dutch Photography Museum is incidentally housed somewhere below the green loft on the right.

Overview of Wilhelminaplein in Rotterdam showing the relationship between both previous images.

Posted in Peter, Photos | Tagged , | 2 Comments

Technical tips for amateur photographers

Sometimes there are tips I don’t offer to experienced photography enthusiasts unless they ask the right question first. This is because I feel they should already know all this, and might be offended that I could imagine they didn’t – especially if the issue is pretty important.

But… in practice nobody can know everything. Especially when some things in the photography world have changed gradually or are non-trivial. So many photographers still use best practices that were suitable years ago, but may be outdated. So, pssst… here is a checklist of several such issues. Where applicable, I tried to add evidence.

1. Good cameras and photographers deserve Raw

The question is whether to set the camera so that it generates Raw image files. Your camera’s default is to generate JPG files. Raw files can be seen as the camera’s native format, and may need to be converted to JPG at some point.

Adobe called their open Raw format “Digital Negatives” or DNG. So, to borrow their analogy, the underlying question is whether to save or to automatically discard your digital negatives. If you currently generate JPG files, you are automatically developing and discarding those “negatives“. As the analogy suggests, this is automatic and thus convenient. But it has certain drawbacks.

Originally Raw files were considered a tool for pixel fetishists: the digital photo that you really needed (for printing, for mailing, for websites, for displaying) was in JPG format because most software could only handle JPG files. So Raw files added an extra step and were thus considered by many to be a waste of time, energy and storage space. Furthermore the JPG file format is well standardized, while Raw files were vendor-specific image formats that might become obsolete in the future.

This situation has changed. By now JPG is a 20 year-old image format that is still good enough as an output format, but isn’t really sophisticated enough to store the images which current camera sensors can capture. So assuming you have a good camera, one could argue that you lose a few year’s worth of camera industry innovation if you choose to exclusively work in Raw. Obviously not everybody will care, but it is at least worth knowing what your choice is.

In more technical terms, current sensors have 12 or 14 bit of accuracy and JPG was designed in the time that 8 bit was considered enough. Furthermore classic JPG was designed to discard fine detail and color nuances in order to save storage space: JPG is essentially a form of “lossy compression”. To JPG‘s credit, the tradeoff between image quality and file size is adjustable, but cameras only give you limited control over this tradeoff. Raw files, on the other hand, use “lossless compression”, store all 12-14 bits of information and produce files that may be 1.5-4× larger (this depends on the ISO setting).

Here is an example of the image quality lost by using JPG. These are 100% crops of an image of a bee keeper’s working clothes taken with my Canon 5D Mark II. The Raw and JPG images were actually simultaneously recorded in-camera and are thus automatically generated from the same exposure. I selected the camera’s highest quality setting. No changes were applied to the resulting Raw and JPG files in post-processing: these are pretty much the defaults.

Hold the mouse over the images to exchange the Raw and JPG images. Loading may take a few seconds.

The JPG version clearly has less contrast (but that could be fixed in post-processing) but a lot of details are lost: at this extreme magnification, the photo starts to look like a water-color painting.

The full image (100 ISO, 70-200mm f/4L IS lens, 106 mm, f/6.7, 1/500s).

The claim that “Raw is an extra intermediate step” is a misconception: when you print or view or zoom into an image, you are generating a new derived image – generally at a lower resolution. So in a way, JPG is a detour rather than the short route: your camera natively speaks Raw, compresses the image because storage space was formerly a major concern, after which the image is decompressed so that it can be used (viewed, edited, printed), can be sent (e-mail) or can be shared (web).

In modern software like Lightroom or Google’s Picasa, Raw and JPG both serve as valid input formats. When you adjust an image (e.g. change brightness, crop it, remove dust, adapt the contrast…) no output image file is generated. Only the (tiny) adjustment commands themselves are saved.

Photoshop and its alternatives also support all major Raw formats and can generate many different output formats. If you may edit the image again in the future, JPG is seldom recommended as the intermediate storage format because every additional detour via JPG causes more loss of quality.

Thus, although Raw has few drawbacks nowadays, here are some legitimate excuses to still use JPG:

  1. If you have a camera phone or compact camera and it probably only supports JPG. This means the camera is probably not good enough to worry about subtle differences in image quality.
  2. In general, if quality is not an issue, JPG is good enough. An extreme example: I use JPG to take pictures of street names, etc instead of writing them down ;-)
  3. If you take studio images, you may have the time and skills to tune the lighting, composition and camera settings so that you don’t need to adjust the image at all in post-processing. If you never change your image (no dust, ideal exposure, ideal contast…) JPG may be good enough. You still loose some sharpness, but for portraits sharpness may even be somewhat undesirable.
  4. If your camera has an obscure proprietary Raw format, you may want to use something else for archiving. This is seldom the case today: small manufacturers use Adobe’s well-documented (but not really open) DNG Raw format and major manufacturers get enough software support for their current and older formats anyway.

To strengthen the case for Raw, Your Honor, here are some more comparisons:

Hold the mouse over the image to swap the Raw and JPG images.

Again, the JPG version largely loses skin texture and fabric detail. You won’t really notice this on small prints, but it will limit your ability to crop or enlarge your pictures.

The corresponding full image (100 ISO, 111 mm, f/6.7, 1/500, 70-200 f/4L IS)

As a last example, here is a macro image of bees taken with a macro lens (while wearing the protective clothing you saw in the first picture).

Hold the mouse over the images to swap the Raw and JPG images.

The JPG has less sharpness for the hairs, less texture in the smooth bits and darker shadows (although the latter can likely be fixed).

The corresponding full image (320 ISO, 100 mm f/2.8 macro lens, f/5, 1/250)

More examples at higher ISO values and using different cameras can be found on here on the www.DPReview.com site. Note that when you compare different cameras, you are often also varying resolution and varying the choice of lens. But the a quick look at different cameras confirms the conclusion that a good photo made with good equipment deserves Raw.


2. Photoshop or Lightroom?

Adobe’s Photoshop dates back to the late 1980′s. It is one of the most famous software tools and even brands in the world. Unfortunately it has also grown into a huge program with many features and large add-ons (e.g. Bridge). This is partly because it is used by very diverse types of users. And this is partly because it was designed to be the single, ultimate tool for modifying or generatinging images.

It is consequently reasonably tricky to learn, and requires a pretty disciplined approach to manipulating images.

In 2006 Adobe launched a new product, Adobe Photoshop Lightroom, that only targets the basic needs of (serious) photographers. It is thus designed to cover pretty much everything a photographer does with photos. It focuses on helping the photographer do common tasks efficiently – rather than on providing an ultimate toolbox which can do everything… providing that you can find out how.

The main benefits of Lightroom (compared to Photoshop CS are):

  1. It is lightweight, but still targeted at professional photographers and serious amateurs. “Lightweight” implies easier to use, easier to learn and significantly less expensive.
  2. Lightroom also keeps track of your files (thus covering Bridge functionality). It does keywording, searching, browsing, etc. The files themselves can be stored with normal file names in a normal directory structure. There is support for having different versions of a file (“virtual copies”).
  3. You never create output images unless you need to send (“export”) a file to someone/somewhere else. You only store the original image. And information is recorded on what modifications you selected. This allows you to change your mind and adapt the image later without any loss of quality. It also makes it irrelevant in what order you do modifications, and it avoids having to store and track multiple intermediate or alternative versions of the same image.
    This approach actually works faster on large images because the computer only calculates changes at the resolution or the crop that you are viewing at that moment: on a screen you either see a low resolution overview image, or a high-resolution partial image. This is because screens are typically 1 to 2 MPixels while your camera is likely between 10 and 20 MPixels.
  4. There is no support for layers. Some uses of layers are handled by the previous point. But there are things you can do in Photoshop which you simply cannot do in Lightroom. Many professional photographers thus actually own both, but spend most of their time in Lightroom.
  5. Lightroom covers the entire workflow in one user interface: importing and managing collections of images, common and some less common image enhancements (“Develop”), professional quality printing, and exporting images to a website or web service.

So if the final output of your work is typically still essentially a single photo, Lightroom (or its competitor Aperture) may give you all you need in an elegant, efficient but professional-strength tool.

Here is a rather extreme example of how far Lightroom can adjust a (Raw) image.

Original version of 2011_Paris_249 (100 ISO, 105 mm, f/5.6, 1/200).

Edited version that stresses the shadows above (!) the tower.

The changes made to this particular image were:

  1. Reduced the exposure by 3.5 (!) stops. Yes, the original was a Raw file.
  2. Removing dust spots
  3. Rendering as black and white.
  4. Cropping off the bottom of the image
  5. Increasing the contrast
  6. Applying automatic lens corrections for distortion, vignetting, etc

The order in which such changes are made is irrelevant – unlike Photoshop, the enhancements are applied in a fixed order determined by Lightroom. This “fixed order” may sound inflexible, but actually allows you to apply the required changes in any order you like and backtrack on earlier decisions without having to start over.

Below is a cropped version of the original image superimposed with the final image. The images move slightly due to the applied lens correction.

Cropped original version of 2011_Paris_249. Place mouse over image to see edited version.

Obviously many images need less or even no editing. But, on the other hand, Lightroom even supports some enhancements that are fancier than those shown above: gradient filters and brush-based local enhancements.

Some of the main things you cannot do in Lightroom 3.x:

  • no layer support (although there is a form of masking)
  • no hundreds of creative filters
  • no HDR or panorama stitching (Lightroom can invoke Photoshop to do both)
  • no softproofing of print jobs (a well-known complaint)

So … for photographers, using Photoshop Lightroom as your main tool saves you time. And the end result is likely to be a bit better. This is simply because Lightroom was design for photographers. Photoshop nowadays targets graphic artists, website designers, engineers, print ad developers, etc. You may find that you still need Photoshop occasionally. But Lightroom provides integration support for extra tools and plugins – including Photoshop.


Candidates for additional topics in this article or series:

  • Calibrate the colors and brightness of your screen.
  • I recommend using adding artificial vignetting to many photos
  • image stabilizers as “digital tripods”. 10x slower shutter speed.
  • Beginners should never use the flash.
Posted in Photo Technology | Tagged , , , , , | Leave a comment