VX6953CB datasheet(54/107 Pages) STMICROELECTRONICS

54 / 107 page

Video timing

VX6953CB

54/107

8209023 Rev 5

Down scaler factor

The down scaler factor is controlled by an M/N ratio, scale_m is >= 16 and scale_n is fixed

at 16. scale_m is in the range 16 to 164.

This single down scale factor is used by both the horizontal and vertical scalers. The scaler

acts upon the addressed region of the array which is determined by the x_addr_start,

y_addr_start, x_addr_end and y_addr_end registers.

Figure 18. Example image full scaled by a downscale factor of 2

6.1.4

Subsampling

Subsampling is achieved by programming the x _odd_inc, y_odd_inc, x_even_inc and

y_even_inc registers.

If the pixel being readout has an even address then the address is incremented by the even

increment value either x_even_inc or y_even_inc. If the pixel being readout has an odd

address then the address is incremented by the odd increment value either x _odd_inc or

y_odd_inc.

The subsampled readout is disabled by setting the odd and even increment values to 1.

Subsampling acts upon the addressed region of the array which is determined by the

x_addr_start, y_addr_start, x_addr_end and y_addr_end registers.

For the EDOF focus estimation to operate effectively, the x_even_inc and y_even_inc

registers must be 1.

The equation for the subsampling factor is given below:

down_scale_factor =

scale_m

scale_n

Downscale by 2

Full (horizontal and vertical) scaling

Raw Bayer image

sub_sampling_factor

even_inc odd_inc

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