Lightning Bezel compensation

Lightning Bezel compensation

Bezel compensation

When you display the video across multiple monitors, the monitor’s bezel gaps can introduce space that was not intended to be there resulting in a disjointed image that is not continuous across all displays. With bezel compensation, part of the video is hidden behind the display bezel so that the bezel appears to be part of the video. Using bezel compensation produces a more continuous image across the displays and provides a more realistic experience. It is similar to looking through a window where the window frames block your view. Below is an example of a 2×2 with and without bezel compensation applied.

without bezel compensation

with bezel compensation

Bezel compensation can be calculated in a few different ways. If the display has a uniform bezel size then calculations can be simply performed. Calculations become a little more complex when the bezel sizes are not the same. For instance, some displays will have a larger bottom bezel than the top, or the left can vary compared to the right.
Bezel compensation only applies to edges of the video potions joining to another display. Only the orange edges of the below examples need to be compensated.

Definition of terms:
source_resolution_width = source video resolution width in pixels
source_resolution_height = source video resolution height in pixels
DH = number of physical displays in the row (side-by-side)
DV = number of physical displays in the column (top-to-bottom)
BW = physical width of the display bezel in millimetres when using uniform bezel size
BWL = physical width of the displays left bezel in millimetres when using different bezel sizes
BWR = physical width of the displays right bezel in millimetres when using different bezel sizes
BWT = physical width of the displays top bezel in millimetres when using different bezel sizes
BWB = physical width of the displays bottom bezel in millimetres when using different bezel sizes
OW = physical overall width of the display in millimetres
VW = physical width of the displays viewable area in millimetres
OH = physical overall height of the display in millimetres
VH = physical height of the displays viewable area in millimetres

We are going to look at an example of a uniform bezel sized display, and one that is not.
1) Uniform bezel size
For a 2×2 video wall with uniform bezels we are going to use the following values:
• source_resolution_width = source video resolution width in pixels
• DH = number of physical displays in the row
• OW = physical overall width of the display in millimetres
• VW = physical width of the displays viewable area in millimetres
Firstly we need to know a few dimensions of the display in millimetres.
• physical width of the display bezel in millimetres (BW)
• physical overall width of the display in millimetres (OW)
• physical width of the displays viewable area in millimetres (VW)
BW can be physically measured, or calculated from OW and VW like below:
((OW – VW) / 2) = ((615 – 595) / 2) = 10
Now we need to know how many displays we have in rows and columns.
A 2×2 wall has 2 rows and 2 columns.
So DH = 2 and DV = 2

The last detail we need to know is the source resolution in pixels.
This example uses 1920×1080 so source_resolution_width = 1920
Now we have all the information we require, we can use the formula below to calculate the bezel compensation required in pixels.
(((source_resolution_width / DH) * BW) / VW) =
(((1920 / 2) * 10) / 595) =
(((960) * 10) / 595) =
((9600 / 595) =
16px

width = ((horizontal resolution / number of horizontal displays) – Bezel)
height = ((vertical resolution / number of vertical displays) – Bezel)
h_offset = ((horizontal resolution / number of horizontal displays) + Bezel)
v_offset = ((vertical resolution / number of vertical displays) + Bezel)

2) Different bezel sizes
For a 2×2 video wall with different bezels we are going to use the following values:
• source_resolution_width = source video resolution width in pixels
• source_resolution_height = source video resolution height in pixels
• DH = number of physical displays in the row
• OW = physical overall width of the display in millimetres
• VW = physical width of the displays viewable area in millimetres
• BWx = bezel width in millimetres
Firstly we need to know a few dimensions of the display in millimetres.
• physical width of the display left bezel in millimetres (BWL)
• physical width of the display right bezel in millimetres (BWR)
• physical width of the display top bezel in millimetres (BWT)
• physical width of the display bottom bezel in millimetres (BWB)
• physical overall width of the display in millimetres (OW)
• physical width of the displays viewable area in millimetres (VW)
• physical overall height of the display in millimetres (OH)
• physical height of the displays viewable area in millimetres (VH)
Now the bezel on each side of the display need to be physically measured.
BWL = 10mm
BWR = 10mm
BWT= 10mm
BWB = 20mm
Now we need to know how many displays we have in rows and columns.
A 2×2 wall has 2 rows and 2 columns.
So DH = 2 and DV = 2

The last detail we need to know is the source resolution in pixels.
This example uses 1920×1080 so source_resolution_width = 1920 snd source_resolution_height = 1080
Now we have all the information we require, we can use the formulas below to calculate the bezel compensation required in pixels.
Left bezel compensation =
(((source_resolution_width / DH) * BWL) / VW) =
(((1920 / 2) * 10) / 595) =
(((960) * 10) / 595) =
((9600 / 595) =
16px

Right bezel compensation =
(((source_resolution_width / DH) * BWR) / VW) =
(((1920 / 2) * 10) / 595) =
(((960) * 10) / 595) =
((9600 / 595) =
16px
Top bezel compensation =
(((source_resolution_width / DH) * BWT) / VH) =
(((1080 / 2) * 10) / 335) =
(((540) * 10) / 335) =
((5400 / 335) =
16px
Bottom bezel compensation =
(((source_resolution_width / DH) * BWB) / VH) =
(((1080 / 2) * 20) / 335) =
(((540) * 20) / 335) =
((10800 / 335) =
32px

width = ((horizontal resolution / number of horizontal displays) – (Bezel Left + Bezel Right))
height = ((vertical resolution / number of vertical displays) – (Bezel Left + Bezel Right))
h_offset = ((horizontal resolution / number of horizontal displays) + Bezel Left)
v_offset = ((vertical resolution / number of vertical displays) + Bezel Top) 