DxO Image Science and the ZEISS Camera-Eyepiece DC4 White Paper
At the heart of the new ZEISS digital Camera-Eyepiece DC4 sits DxO Image Signal Processing based on DxO Labs’ embedded image science. This award-winning solution delivers outstanding image quality to these new Zeiss digital products.
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The Camera-Eyepiece DC4 is the digital photography add-on that brings digiscoping capability to ZEISS existing spotting scopes. It gives birth to a line of digiscope products combining the benefi ts of digital image capture with ZEISS traditional top-class spotting scopes. This new line of products is dedicated to serving the needs of wild-life photographers, outdoor enthusiasts and others who are eager to capture extreme telephoto images of scenes who up to now remain an ephemeral experience. DxO Image Signal Processing (ISP) has been tailored to manage the demanding imaging and usability expectations of wild-life-photographers and other digiscope users, the most important being: natural color rendition, detail recognition and visibility in low contrast situations. |
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DxO ISP is an unrivalled solution based on stateof-the-art image processing technology, it is the critical component ensuring that the digital path of the Camera-Eyepiece meets the best-of-class standards of ZEISS.
Carl Zeiss Sport Optics and DxO Labs partnership results in a high performance digital camera nicely extending this recognized Spotting Scope product line as it enters the digital photography world.
DxO ISP is the Key to Image Quality
The optical system of the Camera-Eyepiece projects the telephoto scene onto the electronic sensor. From there, DxO ISP performs the end-to-end processing of pixel signals straight from the image sensor to produce a top-quality visible image ready for display or storage.
To achieve the desired color, contrast and details, DxO customizes the ISP based on the unique characteristics of the optical system and image sensor.
Great ColorsIn digital photography, a key challenge is to deliver great colors under a huge variety of lighting conditions. Great colors strongly depend on white balance correction and powerful color management, both fi elds in which DxO Labs has a proven track record in its award-winning automatic digital image enhancement software, DxO Optics Pro. |
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With the white balance preset modes, users are also provided with manual settings for the most frequent lighting conditions.
Simultaneously, DxO color management achieves optimal color rendition thanks to fine calibration of color profi les for all major illumination conditions.
In low light situations, in which the camera ISO setting increases, the colored noise level also increases and significantly degrades color rendition.
DxO color management adapts to the ISO setting by slightly decreasing color saturation for higher ISO values to reach the best color rendition compromise.
To further enhance fl exibility during image shooting, the DxO color management offers two color modes.
Natural mode delivers faithful colors (closest to the real scene colors).
Enhance mode delivers more vivid and saturated colors for more visually appealing photos. DxO Labs tuned this mode to obtain color rendition equivalent to high-end D-SLRs.
Optimum Contrast Visibility
DxO Lighting also effectively deals with optical effects that degrade scene contrast such as fl are, haze or light diffusion in a foggy atmosphere. More generally it deals with a wide range of lighting and exposure diffi culties that digiscope users may face, including:
Photography is about capturing variations in light intensity and color, and restitute them on an output media as accurately and appealingly as possible. The human eye is extremely adaptable to local lighting variations, enabling us to see both inside a dimly-lit room and through the windows to the brightly-lit exterior, and to discern details in shadows that are thousands of times dimmer than surrounding areas.
- Low contrast (flare)
- High contrast
- Under exposure
- Backlit subjects
- Sharp variations in illumination across a scene
- Incorrect exposure settings or estimates
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Photographic films and digital camera sensors can’t do this. Neither can computer displays or photographic papers reproduce such a range. In order to produce satisfactory results, contrast management tools are essential to bring the luminance range of the real world within the limits of the display media. To overcome these challenges, DxO Labs developed DxO Lighting technology, a unique local exposure and dynamic range optimizer. DxO Lighting brings out contrast in specifi c areas of the scene while preserving highlights, textures, colors and a natural look. DxO Lighting breaks down the captured scene into areas based on luminance ranges and processes each area to best reveal tonal details through automatic localized contrast adjustment. As a general rule, DxO Lighting slightly increases lightness gain in dark areas. This brings out shadow detail while avoiding the highlight clipping that a simple gamma change would cause. A color correction check then ensures consistency with the scene colors. |
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Low contrast (flare)
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High contrast
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Under exposure
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Backlit subjects
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Sharp variations in illumination across a scene
- Incorrect exposure settings or estimates
Sharp DetailsThe DxO ISP for ZEISS Camera-Eyepiece DC4 automatically corrects image softness (blur) removes graininess while sharpening details at the same time. Image softness is both a function of the camera sensor and of the optical system that projects the observed scene onto the sensor. What typically happens with a “softened” optical system is that the smallest possible spot size is larger than the pixel size; therefore sharp details of the scene are degraded or lost and the fi nal image lacks micro-contrast. This phenomenon is also called “blur” or sharpness loss. Furthermore, blur or sharpness varies against two key parameters: the image fi eld and the color. Sharpness is generally highest in the center and spot size varies from blue to red. Then the de-blurring technique needs to account for the sharpness fall-off across the fi eld and the color. At the same time, increasing image sharpness may increase noise visibility. Noise visibility is a complex function of light level, ISO speed setting, the uniformity of objects in the scene, and eye sensitivity.
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In order to resolve the complex issue of compromising between sharpening and graininess reduction, DxO Labs has developed an innovative method to easily characterize noise within an image. This measure, called BxU, relates to the size of the spot induced by noise, and allows the simple adjustment of sharpening and graininess reduction filters.
DxO sharpness correction locally adapts the level of deblurring measured with BxU, to apply very strict noise control, keeping noise below the level of perceptibility.
DxO graininess fi lter increases the signal noise ratio locally by smoothing homogeneous parts of the image while preserving details in textured areas.
The combination of DxO sharpness and graininess reduction typically allows an average increase of image sharpness by 1.5 BxU and signal to noise ratio (SNR) up to 5dB (depending on ISO setting), without loosing details.
Parameter Settings
Several parameters are selectable for photographers who wish to have full control of image capture and storage parameters. Here is the list of user- selectable parameters with respective values:
| File format | Uncompressed (Tiff) Compressed (Jpeg: high - medium - low) |
| ISO Speed | Auto ISO 50 - 100 - 200 - 400 - 800 |
| White Balance | Auto Presets: Day Light, Haze, Shadow, Sunset/Sunrise |
| Color Fidelity | Natural Enhanced (visually more appealing colors) |
| Exposure Adjustement | None EV-bias (-2, -1.7, -1.3, -1, -0.7, -0.3, 0, 0.3, 0.7, 1, 1.3, 1.7, 2) |
| Contrast Enhancement | On Off |
| Sharpness | Low - Mid - High |