Step by Step Presets: Brightness and Contrast

Let's get to the point with the help of test pictures from DVE High Definition for setting up the correct brightness and contrast levels. Newcomers will notice that when setting up the picture parameters for the first time that logic does not always come to play, but the goal is achieved. The whole operation goes something like:

1. The "Brightness" function serves to set up the darker picture regions.
2. The "Contrast" function enables the lighter picture regions to have a degree of luminosity without being too intensive and saturated.
3. These two controllers oppose each other, and the effects of one will affect the other. Hence, a second round of adjustment is required to test the result.
4. A critical inspection of the color values at this point is beneficial; as unknowingly, altering the brightness and contrast settings could introduce an unwanted color cast to either the lighter or darker picture areas.

All the necessary picture material required for the setup can be found in the DVE High Definition "Test & Calibration" section right at the beginning of "Video Calibration" in the first subchapter.

In the so-called "Pluge" test picture, to the left and right of the central gray graduated block are three vertical strips on a pure black background. If these vertical strips cannot be seen, then the brightness needs to be set a little higher. If the black background appears gray, then the brightness should be reduced. The brightness control has been optimized when the darkest strips on the outer edges are just about visible and almost melt in with the black background. Easily recognizable in this correct brightness setting, are the two vertical peripheral strips with two and four percent brightness respectively.

The four gray graduations in the central strip, starting at 100% brightness at the top with each adjacent one having 25% less than that of its neighbor, serve to give an instant overview of the color purity - called "gray tracking". An alternative but darker test picture for brightness control is "Window 20% w/Pluge", which is recommended, in particular, when the maximum contrast available to a particular set being adjusted is low.

Brightness control visualization based on the "Pluge w/Gray Scale" test picture which can be found in the "Video Calibration" section on the Digital Video Essentials HD DVD:

The correct setting: The very dark strips to the far left and right of the test picture along with the black background appear almost as a single entity. Easily distinguishable are the two adjacent strips with brightness values of two percent and four percent respectively.

If all three dark strips appear quite clearly on a gray background, then the brightness is too high.

If only one or none of the strips are immediately apparent, then the brightness setting is too low and the picture appears swamped. All the fine details present in darker scenes just get lost in the murkiness.

The "Ramps & Steps, Luma" test picture contains whiter than white (WTW) and blacker than black (BTB) components that are positioned on the outside edge of the picture, and are distinguishable by three dots.

The test picture, beginning with blacker than black (digital '0') on the outside has standard black (16) adjoining it. On the inside, the whiter than white (255) element has standard white (235) adjoining it. When the contrast setting is excessively high, then either the two top gray bars merge to form one bigger bar, or color errors are introduced.

Not all video material is capable of reproducing these extreme WTW or BTB components, and certainly not all televisions or projectors are capable of displaying them anyway. In which case, the marked area in the central portion of the test picture should appear without any clipping or introduced color casting. Of the 23 individual gray tones of the full control test picture, at least 21 must be clearly distinguishable.

In addition, the black & white test picture serves to highlight, subjectively, any color deviations that may have occurred while simultaneously acting as an optical control of the color temperature across the complete gray color spectrum.

Setting up the Brightness and Contrast on the Samsung 52 M 86: The controllers are clearly and logically labeled and work perfectly.

To setup the contrast correctly, one needs a picture with gradual differences in light and dark tones. The contrast is only then correctly setup when the lighter areas do not merge together or become consolidated. Particularly well suited to contrast adjustment is a combination picture comprising gray graduated steps together with a gray blend at both top and bottom of the picture as consolidation and/or color casting becomes quickly apparent.

When the perfect contrast setting has been attained, the last but one white strip does not show any color cast, and the whiter than white strip at the outer edge is discernable from the background equally without a color cast. If the whiter than white strip is obviously not lifted from the background, then the contrast setting is not at its full potential and needs to be increased a little. This procedure sounds more difficult than it is. In practice the contrast is increased up until the point where there is no difference seen between the first two light strips, in which case the setting should be knocked back just a touch.

Contrast setup visualization using the "Ramps & Steps, Luma" test picture found in the "Video Calibration" section:

The correct setting: The gray steps are clearly distinguishable right up to the penultimate standard white one. The whiter than white strip is just visible, and even the gray blend at both top and bottom of the picture is uniform and not eroded.

If the whiter than white strips are still visible at the ends of the gray steps, but the overall picture appears dull, then there is not sufficient contrast, which may be remedied by increasing the contrast setting.

Too much contrast results in light gray strips overshooting the marking for 100% white. The visual result of this effect is that clouds, for example, appear as blocks of white.