Monthly Archive for: "September, 2018"

Edge Correction is an additional correction that improves the keying quality.

Click on the icon Edge Correction in order to open a window.

The Brightness function is responsible for correction of the semitransparent areas (like a correction of hair tips that should be darkened/brightened), affecting the image’s natural effect.

The Shrink function is responsible for reducing the object’s contour by softening it.

This is especially important for certain types of cameras, image from which can produce a white line around the object. It is possible to remove it with the Shrink function. You can also use it in the cases where keying is difficult in some places, due to the properties of the object’s edges or lighting. Be careful
not to trim the edges of the object too much, so that it doesn’t look unnatural.

Functions in the Spill Correction section eliminate from the object a reflection effect of the keyed background color. The picture below shows an impact of green color on the object – view before the spill correction.

Click on the icon Spill Correction to open the spill correction window. Despill Color and Despill Coarse functions are the functions used for preliminary elimination of unwanted color on the basis of RGB (red, green, blue) plane.

When you move the Despill Color slider to position 0 (to the left), the algorithm will automatically subtract the green color component, in the case when green is a keyed color (similarly blue when a blue background is used). Whereas moving it to a position 1000 (to the right) will cause adding color red with blue (when green is a keyed color) or red with green (in the case when a blue background was used) automatically by the algorithm.

You can control the value of the algorithm with Despill Coarse function. In the case of green background color, the Despill Coarse function entirely excludes a green component from the object in the RGB (red, green, blue) plane when it goes beyond a certain threshold, resulting in a shift of color to the purple
(magenta) area.

The next function enables more accurate improvement of the correction described above.

When you use the Despill Fine function, the color of the keyed background is excluded, but this time on the basis of chrominance components. Below you can see the Despill Fine slider.

After using the Despill Coarse function, which is an initial correction, the next step is to operate on the precise values. In the case where the Despill Coarse function was set at a high level, any changes in Despill Fine function settings may be of little significance to the algorithm.

As was shown in the previous picture, widening the scope with the White level function usually makes the plane, that formerly had a uniform black color, return to the light gray color scale.

In this case, to correct this gray, the two following functions from Tolerance Correction section are necessary.

Click on the button Tolerance Correction to open the tolerance settings window.

The first function – Luminance – improves the structure of the white mask’s uniform color.

The second function – Color – means returning to a single structure of the black background.

In particular, it improves visibility of an object, when there is a big difference in luminance between the object and the background. In this case, semitransparent objects, like a glass or eyeglasses, become more distinct.

Color function also fulfills a different task. It allows you to eliminate unnatural contours when you disable Show Alpha Matte and return to the actual image. You can remove these contours by improving the limit value between the keyed color and the object.

Click on the button Matte Control to set the initial keying parameters. It is done with the Show Alpha Matte function which, when enabled, shows a mask’s window in black and white. Parts of the mask’s image for which the colors are closer to white will be opaque, and those closer to the dark – transparent.

A view after clicking on the Show Alpha Matte icon.

The expected result is getting a black color of the mask’s background as perfect as possible. In order to achieve it, you have to move the markers on the Black/White slider up until you get as uniform distribution of the black color on the mask’s background as you can.

A view after the Black level correction

Moving the slider to the extreme positions will make the remaining objects lose their properties becoming opaque. Therefore, you have to carefully balance the extent to which you use this function, in order to reach a point where there are still some slight but noticeable differences in the distribution of the black background. The next step is to obtain a uniform distribution of white color on the objects that are to remain completely opaque. This non-uniformity may result from the fact that some of the object’s colors may have color components close to the keyed color. In this case, you can make adjustments using the White slider’s marker.

You can obtain a perfect distribution of a white color on the object by moving the slider towards the maximum value on the left.

A view after the White level correction.

In many cases, the option of White level setting is used together with the Black option, in order to obtain the most efficient settings possible of the black background – without losses in white objects and vice versa.

After selecting the operating mode of the key, the next step is to choose a background color. Click on the button Chrominance Keyer below the Mode button.

A window will appear, as shown below. Now you should choose a background color. There are two options: blue and green. You can change the background color by clicking on a rectangle with a green color. The color of the rectangle also changes then.

In the case of uneven color of the keyed background, you have a button: Detect Color at your disposal. It calculates LRGB parameters of the background on the basis of automated averaging. If reception of these parameters is not successful, the user is notified via a message window and then the default color is set. The Default Color button is used to select the default color.

Click on the highlighted square button Mode to choose the keying mode.

There is a choice between four options:

• Chroma Key – precise setting of the key,
• Simple Chroma Key – quick setting of the key,
• Luma Key – setting of the key on the basis of luminance,
• Disable Key – working with the key off.

Keying is a special filter that in the Reckeen 3D Studio system can be used for camera inputs. The principal of its operation is to remove the areas of a specific color (e.g. green) from the image. The green color is removed after you turn the keying on and set its parameters. This way a figure of a presenter filmed on a green background can be placed against any virtual decoration.

The key can operate in either luminance (luma-keying) or chrominance (chroma-keying) mode. Setting the parameters of the key is done in a few simple steps, through which a special wizard can lead you. Thanks to this solution, selection of optimal key parameters is achievable even for the inexperienced users. And the results are impressive.