Video cameras! DSP, oversampling, optics, media, news...

One of the most important advances in image capture technology is the implementation of digital signal processing systems in video cameras. Cameras with DSP systems can manipulate images in a fully digital environment, in real time and before they are encoded as a video signal.

In its most elementary form, DSP systems make it possible to optimize the performance of automatic camera systems. For example, luminance control does not necessarily have to be limited to the interaction between lens iris adjustment and camera gain. By having DSP circuits it is possible to sectorize the focal plane and apply a different processing to each part of the image. It is also possible to make dynamic gamma and gain adjustments to increase the latitude of exposure, with the consequent improvement in the handling of backlights. In addition, the performance of the camera can be improved in low light, as DSP systems allow you to increase the contrast to improve the apparent definition of dark images. In this way, better results are obtained than with traditional image intensification systems.

On the other hand, most DSP cameras can dynamically couple the balance of blacks and whites, constantly adjusting to color temperature variations. In some cases it is possible to program the camera to maintain its balance based on a particular color. In this way you can keep the same look even if the light conditions vary. In addition, as DSP systems constantly monitor all image parameters, consistent performance is ensured, minimizing drifting or accidental variation of the image caused by temperature changes in the camera electronics. This constant control also makes it possible to compensate for the characteristic defects of color television coding systems, such as the tendency of NTSC video to vary the dye with fluctuations in chrominance levels.

Apart from these basic functions, DSP systems present great possibilities for creative image manipulation. Some cameras incorporate filters or fixed settings that allow you to solve specific problems. One of the most popular is what is known as skin tone detail, a function that allows you to adjust the detail in the components of the image that correspond to the skin color. In practice, the result is a selective diffusion of the image that improves the appearance of the talent. Manufacturers offer it as an electronic system to remove wrinkles and reduce makeup effort without severely affecting the overall appearance of the image, as might occur if optical filters were used for the same purpose. Another frequently used filter is a chrominance noise reducer, which allows to improve the apparent quality of the image originated by cameras with low quality CCD. Some cameras offer an "electronic zoom", and others have image stabilization functions based on DSP circuits.

In the most sophisticated cameras it is possible to paint the image by applying color control parameters that were previously only available in expensive color correction equipment that operates in RGB environment. Each manufacturer defines a color control system according to the vectors it deems convenient, or most useful for the operator. In some cases the image is manipulated according to the parameters of the YUV color space, in others by adjusting RGB values and in others following conventional parameters to adjust the camera's response to black and white. This is really a software problem, and the challenge for manufacturers is to develop efficient color correction systems that can be operated from the camera's viewfinder .

Another interesting possibility is to store camera settings that can be retrieved to resume work sessions with the security of retaining an identical setting to the previous one. Some cameras allow you to archive your configuration on small magnetic cards, on an integrated circuit built into a cassette or on a personal computer. And certain storage systems allow you to transfer the configuration from one camera to another to ensure a perfect match in multi-camera productions.

Some cameras can be programmed to emulate the performance of the most popular film stocks , simulating characteristics such as grain, latitude, apparent definition and color saturation that are traditionally associated with images originating in cinema. In some cases it is possible to originate from the camera the sequence of frames equivalent to a 3:2 pulldown , originating images similar to those of the film telecine film shot at 24 frames per second.

In short, DSP systems open up great possibilities, making cameras more flexible tools. However, the creative potential of DSP cameras must be handled with caution. It's common for a camera operator to make the wrong decisions when applying color correction to images that don't really need it, or to forget to check the camera's status before starting to record. New technology demands a rethinking of conventional work systems, the need to acquire new customs to make the most of the most powerful tools.

For many years the manufacturing processes of lenses did not vary significantly. They were certainly refined, but there were no momentous changes until the popularization of internal focus zoom lenses, which minimize the effect of mechanical lens problems on the camera image. With the refinement of solid-state image sensors or CCDs, the importance of the lens in the quality of video images became evident. In fact, in many cases it is possible to originate images of excellent quality using low-cost cameras with lenses of good specifications.

On the other hand, improvements in the brightness of the lenses and the development of techniques to increase the sensitivity of CCDs completely changed the landscape of lighting work for video. Advances in camera colorimetry allow results consistent with the use of optical filters, and in the new generations of zoom lenses the aberrations characteristic of variable lenses have decreased while the weight tends to decrease and servo mechanisms become more complex.

All these improvements are a consequence of the optimization of existing designs, and have fundamentally been motivated by the vertiginous increase in quality in the electronics of the cameras. However, recently there have been important advances in the design of lenses for video cameras thanks to the questioning of some basic aspects of existing technology.

One of these changes relates to the mechanics of the lenses. Introducing radical changes in the operation of variable lenses has been able to minimize the effect of perspective variation characteristic of zoom lenses, and thus have appeared the lenses known as variable primes, which are nothing more than zoom lenses with performance that approximates that of fixed lenses.

Another important innovation is the introduction of aspherical elements in zoom lenses, which allow to reduce the number of elements that make up the lens, decrease its size and weight, improve the luminosity and increase the definition towards the ends of the focal plane. In this type of lenses, internal reflections are minimized, as the quality of the coatings has also been improved and the effects of halo or repeated reflections in front of strong lights practically disappear.

Thanks to the refinement in the manufacture of the elements, it has become possible to manufacture zoom lenses with greater variations in focal length, with a greater "travel", which retain their performance throughout the intermediate positions. It is especially noticeable the improvement of the image originated in the telephoto position. By manufacturing lighter lenses it is feasible to incorporate teleconverters, which have become a standard feature in lenses for ENG applications. All these developments are combined with the application of ergonomic principles that make the work of photographers more comfortable.

The need to automate production operations has spurred the manufacture of "smart" lenses with computerized controls that can communicate with external systems to achieve movements and adjustments with maximum precision. This technology supports virtual reality applications in which a grapher generates images in real time according to lens variations.

Finally, image stabilization systems have appeared that work thanks to exclusively optical mechanisms. Thanks to a floating prismatic system that follows the movements and vibration of the camera it is possible to maintain a stable image within moderate ranges of vibration and low frequency movements. These stabilization systems have been designed as accessories to ordinary lenses and are offered at relatively low costs.

Camera support equipment has been developed on two opposite lines. On the one hand, with complex electronic systems that allow programming and reproducing complicated movement patterns. Computerized systems apply both to motion control techniques for special effects shots and to the remote control of cameras installed on hot heads or robotic heads. Lightweight cranes with computerized controls have become indispensable accessory for VET productions. It's not unreasonable to see a video camera mounted on a small helicopter, or on a speedy miniature car.

Computerized controls are combined with software techniques for motion detection, so that camera systems are configured that have the ability to follow a moving subject while maintaining a predetermined framing.

On the other hand, many machines have appeared that respond to the optimization of traditional designs. Constant improvements in materials make it possible to build lighter and stronger tripods, small dollys of fluid and silent operation, camera stabilizers that work by gravity and folding cranes of amazing simplicity. The pressure of the consumer market has allowed the development of an infinity of accessories for light cameras that are gradually opening a space in the professional field.

Meanwhile, the development of traditional products such as hydraulic chamber stabilizers, heavy cranes, grips and jibs that gradually receive the contribution of electronic controls to improve their operation continues.

The DXC-D30 camera is the first model in Sony's professional line to incorporate the TruEye DSP system for digital video signal processing. This camera delivers an image of 850 lines of horizontal resolution that is optimized by TruEye to improve contrast response, edge definition and colorimetry. One of the main advantages of the DSP system of this camera is that it manages to suppress the color shift in the backlights and in the planes with large areas of strong colors. In addition, TruEye has a Skin Detail feature to reduce detail in skin tones.

The DXC-D30 includes a control system called EZ-Mode that allows you to adjust all camera parameters according to a pre-stored configuration, although the operator can easily control all camera and DSP system settings from the viewfinder. When used as a camcorder with a DVCAM recorder, the DXC-D30 stores its settings on tapes, allowing you to retrieve these settings or transfer them from one camera to another with ease.

Although the DXC-D30 is part of the DVCAM and BETACAM SX product line, it maintains compatibility with analog recorders and all accessories of the popular DXC-537 and DXC-637 cameras. This allows owners of this type of camera to take advantage of DSP technology by changing only the head of the camera, without losing their investment in lenses, adapters, CCU and other accessories. In addition, Sony offers a control system with triax connections, especially suitable for applications with long cable paths, such as sports productions or news applications.

Sony updates its line of broadcast cameras with the new models of the BVP500 series, which significantly improves the specifications of the previous models by offering a resolution of more than 800 lines and a complete repertoire of DSP function controls. Especially interesting is the possibility of storing camera settings on small static RAM cards and the ability to monitor several images simultaneously in the viewfinder, a function that can be useful in studio applications. This product line includes models with the ability to generate 16:9 ratio images without loss of physical resolution.

- Prosumer cameras use the DV format

Sony offers two models of low-cost prosumer cameras aimed at the event videography market or news coverage in small markets. The VX1000 is accorder of the HandyCam line, equipped with three CCDs for recording DV digital video with 5:1 compression. The DSR-200 is a DVCAM camcorder closest to the professional team. This camera is attractive for the corporate environment because it offers an excellent cost-benefit ratio and compatibility with the professional DVCAM line. The two cameras manage their automatic controls using basic DSP functions.

The Sony DVW700 camcorder was designed to produce images that look similar to those originating in cinema. This model has a sophisticated DSP control system and records 2:1 compressed digital video on Digital Betacam cassettes. Sony proposes to adopt the DVW700 as part of a production model it calls electronic cinematography. The idea is to replicate in video the work systems characteristic of the cinematographic production of advertising or plot pieces taking advantage of the similarity between the cinema images transferred to video and the images originated by the DSP system of the DVW700. Optionally, this camera allows you to generate images in 16:9 format that can be post-produced with current Digital Betacam equipment.

Among the facilities offered by Sony to implement this production model is the availability of memory cards that allow you to program the camera to emulate the look of some types of film. Despite the DSP processing, the camera retains some of the video's own features, especially the limited contrast range and low exposure latitude. However, the image quality is sufficient to replace the film in many applications.

Sony continues to offer its products based on the Betacam SP format, which have ensured their continuity in the market for several years. Especially noteworthy is the UVW-100 camcorder, a low-cost unit that has great penetration in the news market. Additionally, Sony has available a wide range of products in the broadcast and professional lines that include separable camcorders that can be used with the new digital camera heads and integrated units such as the BVW400 and BVW600, analog cameras of excellent quality.

WWW: http://www.sony.com

Panasonic's proposal for the events market is the EZ-1, a small three-CCD camcorder of novel design that clearly competes with the Sony VX1000 for this segment of the market. The EZ-1 weighs less than a kilo and incorporates an electronic image stabilizer and a "digital zoom" that visibly deteriorates the image. The EZ-1 is very often used in ENG applications, as the image quality is sufficient to post-produce it in analog formats with acceptable results.

The AJ-D700u is a DVCPRO camcorder with a resolution of more than 750 lines that Panasonic intends to position as a replacement for Betacam SP cameras. Its DSP implementation is similar to that of traditional camera controls, although it includes additions such as detail controls in chrominance and skin tone detail. You also have the possibility to store configuration files on electronic cards. Despite differences in image quality, some news production companies include an EZ-1 as a backup to production equipment based on the AJ-D700u.

Additionally, Panansonic continues to promote its analog equipment, especially the SuperCam, an SVHS camcorder that was the first camera in its category to incorporate automatic controls based on DSP technology.

WWW: http://www,panasonic.com

JVC offers a complete line of cameras with DSP processing and the ability to generate images in 16:9 format. Among the interesting features of its product line is the electronic image stabilization without loss of resolution, which it offers in its KY-D29U model.

JVC considers the DV format to be perfectly suitable for professional-quality video recording, and that's why it offers the BR-D10U, a dv-format attachable recorder with professional features that can be connected to any analog camera head. Additionally, JVC offers several camcorder configurations based on its DIGITAL-S format, which records digital video with 3.3:1 compression using the BR-D40U recorder.

JVC also operates a line of analog cameras such as the KY-29U and X2-B especially suitable for low-light work, which are aimed at the news and corporate market. These cameras can be configured as camcorders with analog or digital recorders of any format.

WWW: http://www.jvcpro.com

Hitachi presented at NAB'97 the SK-3000 HDTV camera. This is a hybrid camera that simultaneously offers HDTV and NTSC signals in a 4:3 or 16:9 ratio. This camera is ideal for installations that need to make a gradual transition to the HDTV production environment. The camera operates constantly in 16:9 format, and the 4:3 signal it delivers corresponds to the central part of the image captured in the focal plane. Internal processing reaches up to 20 bits, and the camera can be seamlessly integrated into analog or digital installations of any kind.

Additionally Hitachi introduced the Z-2010, a high-sensitivity DVCPRO camcorder with DSP functions, and the Z-V1, a DSP camera head suitable for ENG/EFP applications that can be easily integrated into analog environments, configured as a camcorder of any format and also shares all the accessories of the other Z series cameras.

WWW: http://www.hitachi.com

ProMotion offers a complete line of camera support products for lightweight equipment, including FlightStick camera stabilizers and the lightweight crane known as MegaCrane. This crane is installed on an ordinary camera tripod, reaches a maximum height of 4.5 meters," has a mechanism to replicate the movements of the tripod head at the base of the camera.

According to the manufacturer, the crane can be assembled in less than 15 minutes.

MegaCrane supports cameras up to 25 pounds in weight and costs less than $1000.

WWW: http://www.webpromotion.com

Cyclops is one of the most sophisticated motion control systems on the market, developed by Mark Roberts Motion Control, an English firm specialized in computer equipment for special effects. It is a robotic camera mount, a fully automated study crane that allows previously programmed movements to be made with maximum precision. Cyclops can be controlled from a panel connected directly to the machine or from an external computer.

The main applications of Cyclops are in the realization of shots for special effects, combination of graphics with real images and in installations of virtual sets. However, it can also be useful in all studio applications that require precise movements. It can even be used to automate "live" sequences with complex camera movements.

MRMC also offers a motion control system designed for outdoor use. Milo has similar characteristics to Cyclops, although its size is smaller and operates on conventional rails. One of the most interesting features of these equipment is the target tracking system, which allows them to compensate for the mechanical limitations of the equipment to achieve straight-line movements that are very difficult to achieve with conventional study machines.