Chess contrast. Dynamic Contrast is a technology that improves picture clarity. Contrast as a transfer characteristic

Everyone knows perfectly well that cameras are not perfect and do not always accurately select the color (light) in the photo. It happens that the flash does not have time to charge and we see an almost black square of Malevich, sometimes it works too hard and we see a white square by an unknown artist with red dots in the middle (the eyes of a hamster), and it happens that we try not to depend on the flash, try to shoot without it, and the photo turns out to be a yellowish-brownish muddy shade. All this can be easily cured using Photoshop (of course, within reasonable limits! Of course, a completely black or completely blown-out frame cannot be restored).

How to properly change brightness, contrast and saturation

Let's start first with some brief and then brief definitions in order to understand what we are changing.

What dictionaries tell us on this topic:

Brightness - light characteristic of bodies. The ratio of the intensity of light emitted by a surface to the area of \u200b\u200bits projection on a plane perpendicular to the observation axis.

Contrast - distinguishability of the object of observation from the surrounding background (monochromatic radiation); color contrast is a type of optical contrast associated with the difference in color shades.

Saturation - in physical terms, color saturation is determined by the nature of the distribution of radiation in the spectrum of visible light.

Ghm ... Indigestible terms ... I'll try to formulate it in a simpler way and regarding this topic:

Brightness - the amount of white in your photo. The higher you set the brightness, the brighter the frame becomes.

Contrast - the difference between different adjacent colors. The higher the contrast, the more abruptly we observe the transition from one color to another (sometimes the contrast works as a sharpening).

Saturation - how juicy and bright this or that color looks for you. You can increase it within immodest limits - then the photo even begins to "cut" the eye.

You can, of course, describe each of these characteristics point by point, but that would be wrong. It is correct to complexly change all three frame settings. How? Now let's analyze ...

Let's take for consideration such a dark, low-contrast photo ...

These commands are hidden in the "Image" menu, then "Correction", then "Brightness / Contrast" and "Hue / Saturation":

and

When we press the "Brightness / Contrast" button, we see this window:

When you select Background Color / Saturation, this is:

To begin with, open the "Brightness / Contrast" and calmly and peacefully move both sliders to the right to the desired brightness and contrast (all this is done in a purely intuitive way and in each case in its own way!). You should not always set exactly the same values \u200b\u200bas in this frame here:

It seemed to me that first you need to set the brightness to +120, and the contrast to +30. But everyone can see that the colors are too bright and unnatural. It's good that we know where the Background / Saturation menu is located, which will help us fix this:

It seems to me that if you reset the saturation value by 13 points, it works well. That seems to be all, but I always play it safe and once again go to "Brightness / Contrast", checking, maybe something else needs to be changed to achieve the most beautiful result and realistic photo:

It seems that if you add 20 units of brightness and 10 units of contrast, it will be even better.

Let's see the result in comparison:

Contrast

Contrast - in the most general sense, any significant or noticeable difference (for example, “Russia is a country of contrasts ...”, “contrast of impressions”, “contrast of taste of dumplings and broth around them”), not necessarily quantified.

Contrast - the degree of contrast, most often expressed quantitatively as a dimensionless quantity, ratio or logarithm of ratios.

Basic meanings

Quantitative characteristics

Contrast as a transfer characteristic

In quantitative measurement, in contrast to the previous group of meanings of the term, the ratio of the differences of two measured quantities, the output signal and the input, is used.

In the context of optical and photometric measurements, the term is used contrast ratio or contrast ratio... A similar parameter of the transfer characteristic in electronics is called ac signal gain.

• Lowered lens contrast - an integral characteristic describing the decrease in the contrast of the image formed by the lens in comparison with the contrast of the optical object. Depends on lens aberrations, coating, lens processing, frame features, scene and lighting. Usually not standardized or described by an exact number or graph.

Other meanings and terms

• Contrast (statistics) (eng. en: Contrast (statistics)) is a linear combination of two or more average values. In the simplest case, the difference between the two mean values.
• Cold and hot shower - alternate change of water temperature from the coldest to the hottest and vice versa.
• Linguistic, or semantic contrast (eng. en: Contrast (linguistics)) - opposition (eng. opposition) between the two parts of the argument.
• Contrast agent (eng. en: Contrast medium) - a substance added during medical examinations (usually with radiography and fluoroscopy) in the body fluid to obtain a more contrasting image of the examined organs. For example, Barium Sulfate, Iodolipol.

Notes

• Photocinema: Encyclopedia / Editor-in-Chief E. A. Iofis. - M .: Soviet Encyclopedia, 1981. Articles:

Wikimedia Foundation. 2010.

See what "Contrast" is in other dictionaries:

CONTRAST, contrast, many others. no, wives. (book). distract. noun to contrasting; the presence of contrast. Ushakov's explanatory dictionary. D.N. Ushakov. 1935 1940 ... Ushakov's Explanatory Dictionary

CONTRAST, oh, oh; ten, tna. Ozhegov's Explanatory Dictionary. S.I. Ozhegov, N.Yu. Shvedova. 1949 1992 ... Ozhegov's Explanatory Dictionary

Transfer from CNET

Do you want to know why such an important image parameter as contrast grows infinitely and remains incomprehensible to many?

Understanding what contrast is and how to measure it will help you choose the best TV based on your capabilities. But this is a little more complicated than it might seem.

Basically, contrast is defined as the difference between the brightest and darkest picture a TV can reproduce. A more precise formula:

white level / black level \u003d contrast.

If a TV can emit 45 fL with a white screen and only 0.01 fL with a black screen, it has a contrast ratio of 4,500: 1. Unfortunately, in reality, things get more complicated.

There are several ways to measure contrast. For example, a manufacturer can measure the maximum light output of one pixel at some maximum inaccessible in the usual mode, then measure the light output from the same pixel in the complete absence of a signal. Such a situation is hardly possible with the usual viewing of films and TV programs, but without a generally accepted standard for measuring, such trifles do not bother TV manufacturers.

Moreover, contrast ratios have recently grown to such extreme values \u200b\u200bthat sometimes there is literally no way to measure them. Why did this situation arise? The marketing department declares the numerical values \u200b\u200bwith which it can sell the product. Specialists-developers, in the end, have to be cunning and, lo and behold, the TV gets the necessary contrast. The only way to find out the real abilities of TVs is to read reviews, but even they are not always accurate, as we will see below.

Contrast ratio: good and bad

Since you are reading this article from a display that has a different contrast ratio, you cannot give you real examples of what good and bad contrast looks like, so you will have to look for other ways.

You can check how well your monitor is configured by reading dedicated articles. And below are two images, on the left with good contrast, on the right with poor contrast.

The left image is more accurate with good contrast. On the right, the contrast is worse, the black level is higher.

It's pretty easy to note that the picture on the left is more correct. The picture on the right has a higher black level, and when choosing from two TVs side by side, the choice is unambiguous.

Contrast: natural and dynamic

There are two types of contrast. Most often they are called natural (native) and dynamic. The natural contrast is the one that the display technology allows without trickery. In the case of an LCD display, this feature is determined by the liquid crystal panel. In the case of DLP technology, everything is determined by one or three DMD chips.

Imagine the above images on your TV screen. Natural contrast is determined by comparing the darkest part of an image with the brightest elements in the same scene. Let's call it "the internal contrast of the plot", although, maybe someone has better definitions in this regard?

This contrast is different from what is currently attributed to most televisions, which is called dynamic. Dynamic Contrast Ratio is an extended term for a technology that allows infinitely high readings compared to natural contrast. When playing a movie or TV program, the TV adjusts the overall luminous flux according to the type of scene being displayed. Perhaps you have manually adjusted the LCD backlight, the TV does the same automatically, analyzing the video being played back in real time.

This grayscale is an example of the relative brightness of the display. With the backlight set to maximum, the LCD is at its brightest but has poor black levels. If the backlight level is set to minimum, the black level will be decent and the overall light output will be insufficient.

Automatic backlight adjustment (similar to the projector's iris adjustment) is performed by the video signal control circuit and allows real-time adjustment of the total luminous flux, depending on what is on the screen at that time. An example of an image using dynamic contrast:

In a dark scene, the TV dims the backlight (or covers the aperture of the projector), so the image becomes darker. At the same time, bright areas on the screen are lost, which also darken.

In a light scene, the TV boosts the overall luminous flux, but as you can see from the gray scale, the increased brightness comes at the expense of a decent black level.

Light scenes become brighter and dark ones blacker. This is very good, and does increase the apparent contrast of the display, but not as much as one would suggest based on the stated contrast settings. A TV with a 5,000,000: 1 contrast ratio is fantastic. I would very much like to see him, it is a pity that he does not exist. An HDTV with a high dynamic contrast ratio may look better than a TV that does not have this circuitry, but it will not be as good as a display with a high natural contrast ratio.

Yes, the LED backlighting of the LCD panel can be turned off, creating a true black color, but this is far from always possible during playback of a real movie. A display with high natural contrast will show bright white text on deep black backgrounds. A high dynamic contrast display may have the same dark background, but the text will not be as bright.

Comparatively, it looks like this:

The image on the left simulates a display with high natural contrast. The one on the right has reduced natural contrast, but increased dynamic. The right image is capable of presenting low black levels, but it does so at the cost of reducing overall light output. The high natural contrast of the display (left) makes it possible without technical tweaks to reproduce as black as possible, and at the same time bright white.

As you can see, a display with high natural contrast is the way to go. Against the background of an inky black sky, the glare of street lamps is clearly visible. During the day, the sky is bright, but the black jacket is dark enough. It looks more like a picture on CRT TV screens, more like a movie in a cinema, more in line with the real picture.

The technology with the highest natural contrast ratio today is the one used in LCOS home projectors. JVC projectors currently use the proprietary version of this technology (D-ILA). These projectors have the highest natural contrast ratio measured. Sony's version (SXRD) lags far behind, but comes in second. Plasma HDTVs can be considered the third in terms of natural contrast, although some DLP projectors are close to them.

LCD TVs have made great progress over the past decade, but still lag behind other technologies in a number of ways. Fortunately, the best manufacturers are aware of this and have come up with several ways to mimic the high natural contrast inherent in other technologies.

The best way for LCD TVs to achieve high contrast within a scene is to use local dimming. In this case, the display backlight is an array of light-emitting diodes (LED sources), the brightness of each of them can vary depending on what is shown on the screen. Although this is not done and not at the pixel level, and the LEDs are not individually controlled, but by zones, as a rule, the overall effect is very good.

Unfortunately, most manufacturers today have given up on full LED backlighting, which is the only type of good local dimming. These TVs are more expensive to manufacture.

Most LCD LED displays today use side (edge) backlighting, which places the backlight LEDs on the top and bottom of the LCD panel. Several companies have developed methods for dimming specific areas of the screen and for such backlighting (Edge LED), but the effect is not as good as using a full LED array behind the screen. Many side-lit TVs look great though.

Measurement and all other problems

However, you naturally have a question for a long time: How can you find out which TV in the store has the best contrast? Good question. However, the increased brightness of the lighting distorts the actual capabilities of the TV. In addition, some models may have a glossy screen coating, while others are anti-reflective, which also makes comparison difficult. As already mentioned, all manufacturers give overestimated contrast ratios, which have little to do with the real capabilities of TVs. Therefore, you shouldn't really trust the specifications.

So it remains to read the reviews. Unfortunately, only a few sites do contrast measurements during testing. And the obtained indicators can sometimes vary greatly, which is understandable, moreover, there is no single standard for measuring contrast. Someone might estimate a contrast ratio of 20,000: 1, while another tester would only get 1,000: 1.

Much depends on what you measure. You can take a black field (brightness 0 IRE) from a tuning wheel or signal generator, and then a white field (100 IRE) from the same sources. This will give you a decent overall contrast, but it is not very relevant in real-world video viewing (which is never completely dark or completely white). In addition, numerous video processing systems begin to work on real material, which affect the brightness of individual areas of the image.

An ANSI contrast measurement would be a good addition. In this case, eight black and white squares are displayed on the screen in a checkerboard pattern. All measurements are averaged. This gives a good idea of \u200b\u200bthe display's capabilities, and is much more relevant to actual video. A particular problem is that the brightness of the white fields can affect the measurements of the black squares. Thus, in order to do everything right, you will have to spend a lot of time.

Conclusion

In this case, there is no definite answer. This is precisely the conclusion that can be drawn from everything written above. The best that you can hope for today in order to get a general idea of \u200b\u200bthe vending HDTV models is fairly accurate measurements given in TV reviews from competent sites. And also the knowledge gleaned from this article will be very useful to imagine what potential TV capabilities will best unfold in the viewing conditions in your home.

As with many TV selection guides, the following can be said. Much depends on the conditions in which you intend to watch TV. If you are a movie lover and watch TV in a dark room or at night, the increased contrast of the plasma will look very cinematic.

If you watch TV more often during the daytime, nothing beats LED LCD in brightness. Somewhere between them are LCD TVs with a local or zone dimming system for LED (LED) backlighting. They can provide better "internal scene contrast" than conventional LCD displays, but with sufficient light output headroom.

Regardless of what kind of TV you have in your home, it is very important to set it up correctly, as the initial factory settings cannot fully reveal the full potential of the TV.

(CRTs) have completely disappeared from the shelves of computer hardware stores, giving way to their liquid crystal brethren. People unfamiliar with this technology are often confused in terms, since there are several names for the same subject at once. To avoid misunderstandings, let's get this point clear right away: LCD, LCD are all the same liquid crystal technology, not different. LCD stands for Liquid Crystal Display. Indirectly, the term "TFT" can also be attributed here, meaning the use of thin-film transistors to drive the matrix. Since they are not used in CRTs, it is obvious that the mention of TFT also refers to LCD.

Replacing old CRT monitors with modern LCDs, many owners have encountered a surprising phenomenon - at first after the transition, their eyes start to hurt, and some even have this question - "how is it done for the eyes." There are many recommendations on the Web, but most of them are incomplete, because the very reason for what is happening is cleverly overlooked. Indeed, if monitor contrast and brightness in LCD and CRT technologies are similar concepts, then where does the discomfort in the eyes come from when working with LCD? After all, this should not be. The real reason for eye fatigue is that the principle of operation of the backlight is based on gas discharges in the tube, and even modern LED backlights also flicker (read about PWM LED control). In addition, the glow color of both the lamp and the diodes is unnatural, it has a flawed spectrum. "By eye" it is imperceptible, but the visual receptors cannot be fooled.

In general, monitor contrast is a numerical value representing the ratio of the difference in brightness between the lightest white point to the darkest black point. Indicated in monitors as "xxx: y". In fact, this is a different way of recording. For example, the contrast of a monitor with a maximum dot brightness of 300 cd / m2 and a minimum of 0.5 cd / m2 will be (300-0.5) /0.5 \u003d 599: 1. It is generally accepted that the higher the contrast value, the clearer the picture. This is partly true, but only up to a certain limit, since an infinite increase leads to image distortion (light details on a white background are no longer distinguishable). If the contrast of the monitor is not adjusted properly, then this is one of the reasons for the feeling of grit in the eyes when changing from CRT to LCD.

Note that all methods of setting parameters offered on the Web are subjective. Each user should make adjustments based on personal preferences only. The Windows 7 operating system has a built-in monitor brightness setting that allows you to optimally set the brightness, contrast and gamma values.

On the desktop, press the right mouse button, follow to "Screen resolution", then "Make text and other elements larger or smaller" and "Color calibration". By clicking "Next", we follow the advice of the wizard (there is also detailed help here). At the end, you will be asked to customize the display of fonts using the Clear Type technology: in the samples, we indicate the clearest and "thickest" lines of letters.

Additionally, you can customize the monitor itself. To do this, set the contrast to 20-40%, and achieve a high-quality image with brightness. In some cases, the brightness can be zero, which is quite acceptable. The color temperature (deviation in the yellow or blue spectrum) must be set on the basis. A yellow tint is considered more natural, corresponding to the color temperature of sunlight (6300 K). Various image enhancement mechanisms and dynamic contrast ratios prevent the monitor from setting up correctly, so you need to compare Better and Natural modes to find the best one for you.

Practically the most important parameter that determines the quality of a monitor or screen is contrast. This term is understood as the maximum difference between the darkest color (ideally, absolute black) that the screen can display, and the lightest (white).

There is no exact method by which contrast is measured. For this reason, manufacturers use any that exists today, and the results are passed off as real monitor parameters, although this is not entirely true. These checks create ideal conditions for each mode, which simply cannot exist with daily use of a monitor or screen. As a result, the parameters are overestimated tens of times. Therefore, when choosing a monitor or screen, focus on your own perception, and not on the passport parameters, although you need to know them, but they should not become decisive when choosing.

There are two types of contrast: natural static (native) and dynamic. Natural is the difference between black and white, which the monitor is capable of producing without additional image processing by service programs. Dynamic Contrast is the name of a technology that improves the original performance of a screen. This parameter is provided by software that analyzes the current picture and changes the illumination of the monitor at certain points.

The liquid crystal monitor itself does not emit light; special microlamps or LEDs are used to illuminate the image, which are located behind the screen. To achieve the greatest picture contrast in the dark area of \u200b\u200bthe screen, the backlight is turned off, which achieves a deeper black color. To ensure the brightest white - the intensity of the glow of the elements is increased. This technology is called dynamic contrast. With this, you can increase the real characteristic of the screen many times.

Dynamic contrast can only be realized on a moving picture. If the image is static (for example, text processing in a text editor), only natural contrast is effective, which is the main technical characteristic of the monitor. It is she who in this mode determines the parameters of the image.

When watching movies or playing games, dynamic contrast greatly improves the perception and clarity of the picture. So it is impossible to call this technology completely unnecessary or unnecessary, but this is precisely the technology, not the screen parameter. A display with a high natural contrast will always show deep colors and provide high-definition images, while a dynamic display only enhances the moving picture, while the text on the screen will remain gray instead of black. For this reason, choose those screens or monitors with which you feel most comfortable - we are different and the same parameters will be perceived differently by different people. Focus on personal perception and sensations, but do not forget about the technical parameters.