nConvBuffers

This is used when working with tiled images, which have disk tiles. It represents the number of buffers in conventional memory that will cache the disk tiles. The swap buffers will greatly improve the access to these disk tiles. The default is 1 (one swap buffer will be used to cache the disk tiles).

This parameter specifies how many buffers should be used:

>0, nConvBuffers indicates the number of swap buffers

<0, -nConvBuffers indicates the percentage of the total of disk tiles. For example, a value of -50 means that cache buffers will be used for 50% of the disk tiles.

If this parameter is 0, no swap buffers will be used. This uses the least amount of memory.

It is useful to have more than one swap buffer when you have an algorithm that constantly reads data going up and down. Usually, the data is read in one direction (from top to bottom or bottom to top) – in this case, one swap buffer will be enough. Also, if you only view a certain portion of the image, you might benefit from having enough swap buffers to cache the visible portion of the image (or the bitmap’s region).

The buffers are dynamic: when data is being read/written to a disk tile, a cache buffer is created (if permitted and there is enough memory). If the maximum number of cache buffers for that bitmap has been reached, the cache buffer for the last used tile will be deleted and used for the new tile.