Step 1: Start with a search pattern of all coordinates (x,0) within the search area and find the coordinate with the lowest BDM value.

Step 2: Continue by creating a new search pattern, consisting of all coordinates that are vertically lined up with the current best matching position. Again search the block with the lowest BDM value.

Step 3: Halve the search range. Proceed like in step 1, this time with the row of the current best matching block.

Step 4: Step 2 is repeated with the reduced search range


>

performs the next comparison

>>

performs the next 10 comparisons

>|

performs all comparisons


The grid:
In the lower left you will see a grid. It presents a schematic view of the search area. Each coordinate represents a block within the area.
A red circle marks position that are going to be searched.
A yellow dot marks the current optimal position
A green dot marks the current search position
A black cross marks positions that have been searched

How the comparisons of two blocks is done:
In this applet only grey scale-images are used - this means the images have only one color value per pixel (color images e.g. in RGB format have three).

The algorithm runs through every pixel of the source block and subtracts it from the pixel at the same position in the block compared to. results are squared and summed up. In the end, they are normalized,




dist = distance in color space
c(x) = color value of pixel x