Cine4Home test criteria
The home cinema market is growing continually. With the advent of digital technology, a number of projection systems and television variants have established themselves in the market. Hardly a week goes by without new models being announced or published. They all have advantages and disadvantages.
But how do you assess the quality of a specific device / system objectively? The manufacturer's specifications are often too minimalist and imprecise for use as a reference.
In this article, Cine4Home puts together the essential quality characteristics and test criteria which we apply in our own testing area, among other things. We hope to provide our readers with the essential background information on our tests but also to provide guidelines and suggestions on how to quickly assess whether a device on offer in s shop can actually meet their requirements.
1. Processing
The processing viewpoint is an essential criterion of every test, not only in the home cinema area. Good processing combines the undisrupted functioning and durability of the acquired device. Accurate processing is very important for sensitive technologies such as home cinema systems in particular, as defects have serious consequences. A moderately processed projector, for example, is particularly susceptible to dust and dirt. The consequence is the bother and cost of having to clean the device frequently.
Each device should therefore be examined carefully. Are the parts assembled accurately? Were screws saved and replaced by cheap clip-anchors? Are the materials of high quality? Does the demonstration model already show signs of wear or even dust clots? Does the device make unusual noises during operation or does it become unusually hot? Are the connections robust? All these are aspects that can be checked relatively quickly and with very little effort.
2. Connections
In addition to the robust connections mentioned above, their number is also a non-negligible quality feature. Projectors and plasma TVs are all-purpose devices with a variety of applications: DVD films, TV films, TV sports broadcasts, computer signals, slide shows for digital photos, etc. Even if you do not avail of all these uses when buying the device, you will be pleasantly surprised by a device with lots of ports. Devices bought subsequently can be easily integrated in the system without the bother of switching connections. Simpler devices, especially in the projector segment, sometimes have only a single socket for RGB, YUV and PC signals. Depending on the application, the connection has to be changed.
Special adapters (cables) are also needed for different types of signals respectively. If they are not included in the scope of delivery of the device, which unfortunately is usually the case, they will be difficult and potentially expensive to obtain. And if available, they are usually too short in length or of poor quality.
A good device provides for the most common types of connection, each with its own port: 1 x composite (RCA or BNC), 1 x S-Video) (Hosiden, 1 x YUV (RCA or BNC), 1 x PC (D-sub or BNC).
If they are all available, most devices can be connected in parallel without bothersome special connections. You only need standard cable such as those found in any accessories store. Particularly high-quality projectors / plasma displays offer even duplicate versions of some ports or fully digital interfaces such as DVI.
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3. Supported Signal Types
The same applies for the types of signal as for the number of connections. The more the better. Even future-oriented signal types that are currently not supported in this country should not be missing in an expensive purchase such as a projector or plasma. People are often quick to say "I don’t need that", but who knows what the future holds? Nobody was talking about the PAL-progressive standard for example a year or two ago. But today it is already regarded as almost a "must" for every home cinema. It’s even more upsetting if you have to do without it due to lack of support, or even have to buy a new appliance. This can also be the case with the still rarely found HDTV standards. A better projector / plasma should support all of the common standards, i.e. NTSC (480i), PAL Progressive (480p), PAL (576i), PAL Progressive (576p), HDTV (720p support / 1080i). The following serve as a signal for this:
- Composite (480i / 576i): the worst quality but most commonly used type of 480i / 576i.
- S-Video (480i / 576i): better picture quality, also found on most devices
- RGB (480i / p, 576i / p, PC): best quality in the analogous area.
- YUV (480i / p, 576i / p, HDTV): the type of signal most commonly used in home cinema technology. Universal for almost any standard image used. Almost the same quality as RGB.
- DVI: "new" standard for complete digital image transmission. Provides, at least theoretically, the best possible image quality.
DVI is still rare in plasma TVs but found somewhat more frequently in projectors. Although it is not currently supported, it is possible that it may establish itself in the coming years like HDTV. Devices with this input are thus a safer bet in the future especially if it supports the new “HDCP” copy protection system.
4. Accessories
The supplied accessories are viewed as an integral part of a device. The more generous the manufacturer is by supplying comprehensive, high-quality accessories, the pleasanter the everyday use. A remote control is the minimum scope of supply. It should be of the same quality as the device. Unfortunately, many manufacturers save here. Remote controls in high-end devices are often small, inadequate and cheaply made.
 
We cannot understand these “savings measures”. The remote control is the component with which the user is confronted every day, the "interface" so to speak. Any defect will anger the user again and again, letting the joy in an otherwise excellent device subside.
Other accessories include cables, bags (for projectors) and any necessary adapters.
In addition to the accessories supplied, the optional accessories provided are very important. Adapting your room depends on this. Different mounting options such as wall brackets, feet, and even ceiling mounts should be supplied for a plasma display. The greater the scope of supply here, the more individually the user can plan their room. A robust ceiling mount is the minimum accessory for projectors.
5. Operation
Operating a device is extremely important, especially for everyday devices such as plasma TVs. It consists of a combination of on-screen menus and remote control. Only with a well thought-out combination of both is the operation simple, intuitive to use, yet with comprehensive functions. Like processing errors in the remote control, design errors in the device control will quickly “get on the user’s nerves” and diminish the quality impression significantly. One should therefore look at how a device is operated closely, at the strengths and weaknesses, prior to making a purchase. A graphically sporty-looking interface might look good but quickly leads to confusion with small, non-self-explanatory motives. The same applies for incomprehensible wording and laborious nested menus. The optimum menu navigation is simple, yet graphically appealing, quick to use and intelligently structured.
6. Technology
Every type of display technology has its own homemade pros & cons. Whether it is LCD, DLP or plasma, specific artefacts in the image or other problems are known for each system, e.g. the "rainbow effect" in DLP or the "screen door” on LCD (more on that below). Unfortunately, no technology is "perfect". You should therefore check beforehand if a particular technology with all its restrictions suits your personal taste. Once your decision has been made, you can proceed with the details. The individual problems are larger or smaller depending on the model. High-end models are the ones which are quite successful in combating the limitations of their system. You can find more detailed information on the different projection technologies in our Know-how Special: Large-screen projection - an introduction, details on plasma TVs in our Know-how Special: The basics in plasma displays.
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7. Projection Distance (projectors only)
The required projection distance is important for certain image sizes for projectors. Some projectors require very large distances and only enable acceptable image sizes in large rooms. Others, on the other hand, have a very short projection distance. This may make it easier to mount the device (e.g. on the coffee table).
A device should not require too large a distance. Furthermore, the device should have a zoom lens to provide leeway when setting up and adjusting the size. The projection distances are listed in tabular form as a rule in the manual.
8. Resolution
Digital projectors and plasma displays have a certain built-in "native" resolution expressed in pixels (width x height). This forms the basis for resolution of detail and sharpness. As with so many other things, the same rule applies here: The more the better.
For the normal PAL standard in our country, there are certain minimum requirements starting from which full quality use is assured. PAL DVDs show resolution of 720 x 576 pixels, either in 4:3 or 16:9 format. A projector used predominantly to show films should therefore have at least in excess of 720 x 576 pixels in 16:9 format. Plasma displays on which a lot of 4:3 TV material is also viewed should already have PAL resolution in the 4:3 area. A detailed description of the resolution criteria can be found in our Know-how Special: Resolution and scaling requirements for projectors and Plasma TV's. The resolution is always specified in the technical data of devices.
9. Scaling / Signal Processing / Sharpness
The scaling of a device is just as important as resolution for clarity of picture and detail of display. Input signals such as PAL, NTSC and HDTV do not generally correspond to the native resolution of the video display device. The projector or plasma TVs has thus to convert the resolution "internally", "scale" it.
An example: if a plasma display has a native resolution of 1024 x 768 pixels, the resolution of a PAL DVD with 720 x 576 pixels will not be sufficient to fill the full screen content. The plasma TV has to add 304 pixels horizontally and 192 pixels vertically, or "interpolate". The better the job it does, the sharper and more detailed are the resulting pictures. Poor scaling leads to loss of resolution, linearity problems (the proportions of objects become distorted), and even vertical or horizontal “distorted axes”.
The quality of scaling is not easy to assess at first glance. You need to use detailed, high-quality picture material here. Special resolution and geometry test images like those we always use in our tests are best suited. They are found in many commercially available calibration DVDs. A so-called "burst signal" determines fairly quickly how well the device displays the resolution of the signal, and whether certain proportions appear distorted.
Further information on scaling can also be found in our Know-how Special: The resolution and scaling requirements for projectors and Plasma TV's.
10. De-interlacing
The third crucial component for sharpness and detail representation is the so-called "de-interlacing" of a device.
Unlike conventional TVs, plasma TV's and projectors produce a "progressive" video display. Progressive means that the total resolution is used with each picture. All pixels are fully triggered 50 times per second with PAL, 60 times per second with NTSC.
But most types of signals we use every day just issue “interlaced” signals. Interlaced, also called field (odd field, even field) artificially halves the resolution of our PAL standard. The even and then the odd lines are triggered alternately. It is only through the inertia of the human eye that the images merge to a full picture.
As a result, the individual pixels of a TV are not triggered 50 or 60 times per second, but only 25 or 30 times.
In the same way as it does with scaling, a projector has to internally calculate, interpolate, the missing lines of the picture with an interlaced video source (e.g. TV, camcorder, VHS, etc.). This process is called de-interlacing. The better and more accurately this is done, the more detailed and sharper the resulting images. There are two different de-interlacing application variables depending on the source material:
10.1 De-interlacing of video material
In the case of video material such as shows, sports broadcasts, documentaries, etc. each field corresponds to a snapshot. The image content varies in movement from image to image. In other words; video material consists of 50 different images with a resolution of only 720 x 288 pixels. The de-interlacer must now create an image from each image with 720 x 576 pixels, doubling the vertical resolution. This requires complex algorithms that have to be fast (only 1 / 50 second per image).
Some projectors and plasmas “fail” in this discipline.
10.2 De-interlacing of film material
Footage has always been recorded using only 24 frames per second, i.e. 24 Hz. When transferring to video, you use the high resolution of the starting material to your advantage. Two fields are made for a movie screen – one with all the even lines, one with all the odd lines. Since our PAL standard displays 50 fields per second, the movie is artificially accelerated a little. 25 cinematic images are divided into 50 fields per second.
The task of the de-interlacer now is to integrate these divided fields into the original film images. Each of two successive half-images are woven into a full-screen: line 1 of field "A", line 2 of field "B", line 3 of field "A", line 4 of field "B" and so on.
In this way, the original film images are created, the fields are complementary in their resolution as they are generated from one and the same film image.
This interweaving of fields, in English "weaving," sounds easier in theory than it is in practice. The de-interlacer must “find out” on its own which two fields are from one and the same film image. If it fails to do this, it interweaves "wrong" fields leading to bothersome image changes.
If the necessary information is not in the image signal, a complex image analysis is required, and this in turn under enormous time pressure of only 1 / 50 second.
Most projectors and plasma TVs often have no de-interlacing, and if they do, it is only average.
De-interlacing is probably one of the most complex aspects of the progressive image representation of projectors and plasma displays. If you are looking for detailed information about this topic you should look into our Know-how Special: Progressive scanning in home cinema - introduction to a complex issue.
How do you assess the de-interlacing features of a device? This is not easy. You should have a certain "default choice" of video and film DVDs whose picture features you know well. The test should focus on very detailed picture elements with fine structures. If they flutter or even flicker, the de-interlacer is not working accurately. This effect can seem even worse with vertical movements. If, on the other hand, they are calm but blurred, the image is being interpolated too roughly. A good de-interlacer generates a steady image with high sharpness as far as the signal source allows it to. In our tests, we use a large number of film DVDs and test sequences from calibration DVDs. Special care is required here as the de-interlacing can have many subtle weaknesses.
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11. Contrast, Black Level and Brightness
Equipment manufacturers and dealers advertise their products using simple, adroit technical "facts". Contrast is one of the most popular of these. High values from 1000:1 to 4000:1 are used to convince customers of the contrast quality. This is a little misleading. While contrast is a very important quality feature, it is also just one of many components that are necessary for a good picture. What is contrast composed of? This includes several aspects.
11.1 Black Level
The black level, the darkest displayable "colour", is still not perfectly dark in the digital technology used in digital projectors and plasma TVs. There is always a little residual light that makes black elements in the picture look grey. Manufacturers have been working on rectifying this problem for quite some time, and they have been successful. The black level has become darker and darker from generation to generation. A good black level affects the depth impression even in dark pictures but without impairing three-dimensionality. Poor black levels show a too bright grey as darkest colour. Dark scenes lose vividness and appear "misty".
11.2 Maximum brightness
The maximum brightness of a projector / plasma describes the highest white level the device is able to project. Good brightness is needed to convey a natural picture in bright scenes (outside shoots). If the picture is too dark, everything appears as viewed through a pair of sunglasses. Even bright desert scenes look as though it is cloudy.
11.3 Contrast
The contrast describes the relationship between maximum brightness and black level. A contrast ratio of 1500:1 means the "white" is 1500 times brighter than the darkest "black". The higher the ratio, the more leeway there is for levels of brightness making it more dynamic.
11.4 Assessment contrast / black level
You should only trust the manufacturer’s contrast data under certain conditions. These data are usually the results of laboratory tests which have nothing to do with reality and without the correct image calibration. It is better to rely on your own eyesight here. The black level should be as dark as possible and not affect very dark scenes in a fully darkened room. At the same time, the device should have a good maximum brightness with proper colour temperature (see below). If both of these conditions are fulfilled, the video image should be pleasing to the eye in terms of deep dimensions and clean dynamics, yet always spatial and vivid. In addition to film DVDs, special black and white test pictures from calibration DVDs are good for tests.
You can find more detailed and additional supplementary information about contrast in our Know-how Special: Contrast with digital projectors - How important is it really? or Contrast with data projectors and plasma displays - Useful or misleading information?
12. Gamma Distribution / Homogeneity
A good contrast ratio of a projector / plasma TV given in certain circumstances can only be adequately used with a correct gamma distribution. It describes the distribution of brightness in the image. The more even the brightness distribution, the more precise and homogeneous are the shades in the picture. Dark picture elements should be allocated as much "space” in the contrast area as bright ones. For example, an uneven distribution makes dark elements of images appear well shaded. Bright elements however, lose their structure as there are not enough shades available. Any combination is possible. The medium brightness range may also be "drowned". Basically, if the gamma distribution is incorrect, certain areas appear either too dark or too bright. An accurate image display is not possible.
The gamma distribution is measured in a so-called gamma curve. It places the different brightness levels in relation to actual video display brightness. The "unity" of the brightness levels is the so-called "IRE" level. IRE 0 stands for black, IRE 100 for white, and IRE 50 for medium grey. In simple terms, this can be expressed as "percentages" of white: 0% (black) to 100% (white).
During testing you measure the light efficiency of different IRE levels generated by grey test cards, and enter them into a diagram.
The result should ideally be a curve with a value of 2.2. It takes into account the distribution selected during video encoding and ensures accurate light reproduction.
If the gamma curve deviates from the ideal curve, the effects will be those described above.
An example:
The gamma curve is rising too fast and there are barely any jumps in brightness at the top. In the picture this means that picture elements with average IRE levels already appear too bright. Bright details from 70 to 100 IRE have little "room" to distinguish themselves. The dynamics are lost. In a film, bright clouds would have very little structure, for example. They would look like flat, mono-coloured paper.
Normal users do not have such extensive testing methods at their disposal. They have to rely on their own eyes. A useful test image is a grey scale image. It shows different brightness levels from black to white in an image as a bar.
Care must be taken here that the shades of brightness appear evenly between the bars. In our "bad" example above, the last 4 grey bars would be indistinguishable from each other. The dark grey bars should have clear differences in brightness and not be swallowed by the black. This would result in a massive loss of detail in dark areas.
Cine4Home measures the gamma distribution using high-quality software and sensors. We would like therefore to demonstrate picture properties to the reader in our tests, which can not be perceived as easily with the naked eye, but affect the picture quality significantly.
13. Gamut
The human eye is able to detect a very large number of hues. Even minimal differences are differentiable for us. A projector / plasma should therefore be in a position to display as many colours as possible. The more shades of colour, the more natural and vivid the result. Video electronics currently limits the number of displayable colours. The entire spectrum of the human eye is far from being met. There are however certain minimum standards which an image output device must meet in order to make maximum use of the video standard. This is illustrated graphically by the so-called "CIE chart”. It shows the human colour spectrum in proportion to the displayable colours of the projector / TV.
The black triangle shows the scope of the best current video standard, HDTV. The white triangle shows the displayable colours of the projector. The greater the surface area of the triangle and the more accurate according to the HDTV standard, the better. The chart above shows, for example, very good potential for red and green or weaknesses for blue.
It is difficult to ascertain the colour range without measuring instruments. The user should consider mono-colour test images of the three primary colours: red, green and blue. Even colour films may help in the assessment. If a colour is too pale, the device may have weaknesses here. Please note however: a proper calibration is needed for each test image, otherwise the result will be distorted.
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14. Colour Temperature
Many image tests may describe the colour gamut, that is the colour potential, but ignore the colour temperature, i.e. accurate colour display. The truth of the matter is, it is just as important if not even more important than colour gamut. Incorrectly set or poorer-quality devices are not able to reproduce the true colour characteristics of the original film, leaving the picture distorted. This may not be directly apparent to the viewer. After all, you are used to adjusting your eye so that a picture looks “good”.
An accurate image calibration enabling you to attain the naturalness of the original picture as closely as possible is far more desirable.
How do you calibrate the colour temperature correctly? First of all, you need to know which standards the “makers” of a DVD use for encoding. Film-video transfers are “calibrated” to a certain colour temperature. This colour temperature is measured in units of "Kelvin”, named after the British physicist, W.T. Kelvin. It uses a theoretical body as a reference that is completely black at 0 degrees Kelvin (= -273 ° Celsius), and sets its particular glow colours in relation to the temperature it is heated to.
3000 Kelvin is thus the white that this theoretical body produces at 3000°K.
Normal daylight has a colour temperature of about 5000 Kelvin (abbreviated D50); the midday sun is about 6500 K (D65).
All video transfers are calibrated using the latter, 6500K. All shades of grey in our picture should, without exception, correspond to the exact colour temperature of 6500K. The more precise the factory settings of a projector / plasma are here, the more accurate the colour.
Checking the colour temperature of equipment is relatively easy with the help of measuring devices such as those used by Cine4Home. As with gamma measurement, the grey areas of all brightness areas are measured from 0 to 100 IRE and entered in a chart.
The result shows clearly how accurate the colour is and in which brightness areas the deviations and thus errors in the colour display can occur.
The colour temperature can only be “measured” by a trained eye. An unnatural colour display is most evident in skin colours and faces. Is the actor healthy or does he have jaundice? Does he look pale and “bluish” as if he were ill? You can easily memorize these amusing criteria to roughly estimate the colour temperature of equipment quickly. You can continue by using the test image with grey shades.
All the greys should be internally consistent without a tendency to red, green or blue. It is particularly difficult to estimate white here. People tend to turn white up to "bright". Under an appropriate 6500K, white is not glaring and pale, but rather warm, like an eggshell. Please do not forget: white should be equivalent to the colour of the midday sun.
Additional explanations of the correct colour temperature can be found in the Know-how Special: Contrast with data projectors and plasma displays - Useful or misleading information? And in our Tips & Tricks area: Increase in contrast and black improvement in digital projectors - colour correction and ambient light filter sometimes make miracles happen.
If all that is too much or too complicated, you can simply read the accuracy of the devices from the measured diagrams in our tests.
15. Screen Door Effect
Nowadays, the screen door effect mainly affects only digital projectors of the LCD genre.
It describes the undesired, black space between the individual image pixels. If you sit too close to the screen or have good eyesight, the entire picture appears to be behind a "screen door". At the same time, maximum brightness and contrast are impaired by the dark stripes. Thus, the smaller the distance between the pixels, the better the image result. The proportion of the distances is measured by the so-called "fill rate". It describes the area fraction of the actual picture elements on the overall picture. A fill rate of 70%, for example, means that only 70% of the image is illuminated by pixels, while 30% is “covered” by black lines.
D-ILA projectors achieve a fill factor of 93%, DLP projectors 88%, and conventional LCD projectors only 60% because the conductors block the optical path.
Newer LCD models have special blur functions to increase the filling rate and diminish the screen door effect. An example is the PT-AE300 with smooth screen feature.
The screen door effect does not apply for Plasma TV's. As with normal TVs, the picture is too small in relation to the viewing distance to make individual pixels "visible".
16. Illumination
Uniform (even) illumination is important in projectors. Many older or cheap devices with low-cost optics show a visible loss of brightness at the edges, resulting in the undesired “hot spot”. The picture is too bright in the middle. It looks like someone is aiming a flashlight at it.
Fortunately, illumination with modern equipment and lower price ranges is largely uniform and rarely poses a problem. Nevertheless, Cine4Home plans to include illumination as a test criterion in their future measurements.
17. Shading
LCD and D-ILA projectors are predominantly affected by "shading" effects. Shading describes the non-homogeneous colour distribution over the entire image. Colour shifts (slight "colour spots") can be clearly seen at the edges of the picture.
You can check the shading properties of grey images with medium levels of brightness. Here, colour shifts are usually seen clearly. Almost all LCD and D-ILA projectors have slight shading problems. However, the results can vary from device to device and should therefore be checked directly before purchasing. Shading cannot be detected when showing a film if the device is set properly.
18. Overscan / Pixel Cropping
Film DVDs are “recorded” at a resolution of 720x576 pixels. This full resolution can only be exploited by the projector if it displays the entire image content. However, in order to allow TV manufacturers work within ranges, only part of the image need be displayed. The rest is a type of transition area known as overscan.
The DVD standard still uses the full overscan area almost exclusively for displaying image information, too. The following thus applies: the larger the displayed area of the video display device, the more image information / resolution.
The overscan area can be made visible with special test patterns. You can read the "swallowed" part of the image pixel clearly with them.
High-quality projectors include settings options as menu items, with which the user can optimize the display window.
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19. Noise
Undesired image noise mainly arises only with DLP projectors and plasma TVs. There are technical reasons for this.
Shades of brightness are created by rapid switching on and off the adjustable mirror (DLP) and phosphorus pixels (plasma). The darker the shade, the "slower" the intervals. A visible screen noise can occur with dark colours or shades of grey.
Depending on the make and quality of the particular device, the "interference" plays a larger or smaller role. You can check the image noise with test images that show the difficult colours such as dark red or dark grey. The more noise the video image makes, the worse the image reproduction of dark image content. Plasma TV's and projectors show major differences here. It is definitely worthwhile doing a test.
20. False Contour Effect
The root of the so-called false contour effect is also in interval-generation of shades of brightness in DLP and plasma.
It describes the loss of resolution in brightness of moving picture elements.
Greyscale loses accuracy and there is “disturbance” / noise at the edges. A vertical grey bar loses some of its grey shades, for example, if it is moved horizontally. It looks digitally distorted.
The false contour effect can be tested with specially animated test scenes. If you do not have these, you need to take a very close look when it comes to films, especially those with moving grey picture content.
21. Rainbow Effect
Again, this undesired effect occurs only with DLP projectors and plasma TVs.
Single-chip DLP projectors use a single DMD chip for all three primary colours. They are projected onto the canvas successively (sequentially) using a colour wheel. The three monochrome images only merge to a colour image in the brain thanks to the inertia of the human eye. But with fast movements with strong contrasts the primary colours may still be perceived separately. There is a "rainbow effect". This effect can be reduced with faster colour wheels. Modern high-end projectors have, for example, colour wheels rotating at double speed, thereby minimizing the rainbow effect significantly.
In the case of plasma displays, the colours are produced simultaneously by separate colour pixels, but a type of "lightning" is also evident.
The light periods of different types of phosphorus for red, green and blue are not currently identical. Thus, there is slight ghosting in high-contrast and moving white elements.
The different light periods are also noticeable with fast camera cuts with bright pictures. Viewers with sensitive eyes can make out a so-called rainbow effect similar to the rainbow effect in DLP projection though not nearly as strong.
The rainbow effect varies from model to model. You should therefore test it with your own eyes.
It is extremely easy to “detect”. High-contrast scenes with fast camera cuts clearly provoke it. If you move your eyes while watching these scenes, the "problem" becomes evident very quickly.
The strength of the rainbow effect, however, depends not only on the device used. Not everyone has very sensitive eyes. Some find it unbearable and tire easily, while others barely notice it. Therefore you should check how sensitive your eyes are and take all of your relations who will be regular viewers with you before making a purchase.
22. PC Signal Processing
In addition to video display, a modern projector must also be able to display PC signals well. Sooner or later, all users will use their projector for games, surfing or work. You may even connect a home cineam PC which will further improve the picture quality of DVDs considerably.
Almost all modern projectors / plasma TVs support PC signals, however, very few do it "correctly". Inaccurate signal calibration with scaling artefacts, unsupported refresh frequencies (e.g. 50Hz for PAL) or permanent image judder are often problems the user has trouble with due to poor PC signal processing. An equally widespread problem is the so-called "tearing". Here, the picture is “torn” into two parts during fast horizontal movements. The lower image content does not match the upper.
Problems in computer processing technology occur in all categories of plasma and projectors. Picture judder and tearing are phenomena found particularly frequently DLP projectors.
Computer processing can best be checked with a good HTPC. With the help of programs like PowerStrip, you can test all the relevant frequencies and resolutions. You should pay special attention to the native resolution of the projector. Picture judder and tearing can be seen very quickly if the HTPC displays "liquid" pictures itself.
23. Conclusion
In this article, we have endeavoured to explain the most important, if not all, the quality features of projectors and plasma TVs. Many aspects only provide a very positive “image experience” in perfect interaction with each other. The complexity of the matter quickly becomes apparent. It is therefore important to be fully convinced of all of the quality features of a device before purchasing expensive equipment such as a projector or plasma.
We hope to have provided our readers with some help in understanding our tests and that they will find it easier to assess the quality of devices in the shops from now on.
Ekkehart Schmitt
www.Cine4Home.com
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