Nikon Digital Image Processing Technologies and the D200
Color reproduction and interpolation that reflects user preferences.
The challenge to meet demands for capabilities possible only with digital images continues.
Digital image processing technology has evolved with amazing speed. What are the latest technologies featured in Nikon's flagship digital-SLR cameras, the D2 series?
Generally speaking, digital images can be processed inside digital still cameras using a built-in signal-processing LSI and image processing engine. But cameras alone generally don't have the power to handle functions available with image processing and editing software like Nikon Capture. This type of software makes more advanced processing possible because its large memory capacity makes it more flexible. So in developing the D2H and D2X, we were successful in making hardware capable of achieving what had previously been possible only with software. In other words, the D2H and D2X benefited from a major innovation; they offered in-camera image processing that was as advanced as image processing with software.
I see. That's a big step forward.
This innovation meant that precise reproduction of even detailed patterns was possible with the D2X due to interpolation that could now be performed in-camera. This feature has been highly praised throughout the market because it eliminates moiré while preserving image sharpness.
I'm also impressed with the superior color processing design. Is this also related to the evolution of image processing technologies?
Yes. As I mentioned before, we received a lot of comments and requests from users around the world after the release of the Nikon D1. Among these, an extremely high percentage was requests regarding color reproduction. We came to realize that the colors demanded varied depending upon how the final images were used.
Preferred colors also vary with each country or culture. This difference can be easily explained with reference to portraits. Japanese users, for example, prefer whiter skin tones, while Americans prefer skin tones that appear a little more orange. Consider landscape photos for a moment. Since the color of the sky in Tokyo, Las Vegas, or Amsterdam is surely different, it's only natural that users would have varying preferences regarding reproduction of the blues in the sky. In addition to such preferences, colors also differ depending on how pictures are used or the skill of the photographer. These various demands all led to development of the color mode system. In addition to mode I, which is best suited to portraits, mode II, which offers natural color reproduction, and mode III, which reproduces colors similar those achieved in landscape photos taken with film with enhanced color saturation. Hue can also be adjusted so that the preferred colors of all users can be perfectly reproduced. We have also equipped some cameras with modes Ia and IIIa to accommodate the users of those models more precisely. However, we are taking special care to preserve the basic color design concept for mode II throughout our camera lineup. Mode II has remained unchanged since release of the D1X and D1H, standardizing post-processing among all of our cameras.
I had no idea that color preferences differ from country to country. There is a lot more to image expression than I thought!
Before release of the D2X, we sent a crew to conduct color preference surveys and shooting tests in a number of countries. The information they brought back led us to the conclusion that light sources seem to have a great influence on color preferences. Not only is the sky a different color in a different part of the world, but indoor lighting also varies greatly. For example, fluorescent lighting is very common in Japan, while western countries seem to prefer incandescent lighting with its slightly reddish cast. Therefore, Nikon has improved the level of image design with color tuning under actual lighting conditions in several regions throughout the world.
That must have been a lot of work!
It certainly was. But we believe that digital images designed within the confines of a studio could never express truly natural looking landscape photos. As you know, various tests are performed with development of automobiles. The same goes for cameras. Testing is critical to our ability to reproduce colors that are faithful to the place in which they were captured, regardless of even dramatic differences in light sources and hues.
OK, I understand the importance of that, but I'm still surprised that so much effort goes into developing digital image technologies.
Image design without ever having seen the actual colors would limit the accuracy of color reproduction. So it is very important for designers to experience the colors and atmosphere of each region in which our products are used.
Such perfectionism is what leads to improvements in technology.
I believe that the four most important aspects of image design are to see images, to capture images, to analyze images, and to truly understand user preferences regarding images.
Digital imaging is still in the process of development.
We have to progress from the point of producing “beautiful” images to producing “remarkable” images.
Finally, a successor to the D100 has been released. Tell us about this new camera's image processing characteristics.
The camera itself can be generalized as a successor to the D100 that incorporates the latest imaging technologies inherited from the D2X, such as high-speed four-channel independent readout, and an image sensor with a higher pixel count. It also features a new optical low pass filter with infrared cut coating that prevents images from having a red cast, making it easier to reproduce colors, such as the moss green or brown of a cloth colored with vegetable dye, that are very difficult to reproduce with current products.
I see. It sounds like a professional-class camera.
Yes, you could say that. This camera features the same image processing functions built into the D2X, plus improved hardware specifications. I think we can clearly say that this camera is not only more flexible than the D100, but also offers the excellent performance of the D2X. Furthermore, its low pass filter is constructed with four-directional separation for optical suppression of moiré. Technology for reducing moiré optically has already been used in the D2H and the D100, and is highly regarded in the field of photojournalism, where speed and quick response are very important. The new low pass filter retains image sharpness, which tends to be sacrificed with the D100, and reduces moiré, making this new camera easier to use than the D100.
Was there any specific reason for using a mechanical shutter rather than an electronic shutter?
In order to maintain excellent tone characteristics while radically increasing the effective pixel count of this Nikon DX-format camera to ten million, we were forced to re-examine CCD pixel structure. We decided that a mechanical shutter would be more effective than an electronic shutter. Thus, this camera offers the main advantages of cameras with pixel counts higher than ten million, such as excellent blur characteristics and expression of depth, while remaining very flexible.
I see. Finally, could you tell us a little about your hopes for the future of digital imaging?
Digital image processing technologies have made remarkable progress, but I believe that image sensors will continue to evolve to offer even greater performance and functionality. I think that developments regarding pixel count have just about reached their limits, so new technology should focus on other aspects, such as improvements in tone characteristics, speed, and tolerance for higher sensitivities. At the same time, high pixel counts can be maintained with current technology.
The possibilities in digital imaging remain limitless. For example, there are still many colors that we cannot reproduce. I would personally like to work towards development of a camera that makes the most of the unique possibilities and characteristics of digital images by capturing photos that make all users shout, “That's the picture I was hoping for!” Thanks to the rapid progress of digital image processing technologies, it is getting easier and easier to create “beautiful” images, but I think that users now want to capture “remarkable” images. So, I guess that I would like to apply the know-how I've acquired with my years of experience with video and movies to still cameras so that one day digital imaging will have reached the level where a still image is able to express the same level of emotion that a movie can.