SAMA5D44_14 Datasheet, PDF (655/1776 Pages) ATMEL Corporation – Atmel | SMART ARM-based Embedded MPU

Color space conversion coefficients are defined with one sign bit, 2 integer bits and 7 fractional bits. The range of
the CSCij coefficients is defined below with a step of 1/128.
– 4≤ CSC_ij≤ 3.9921875
Additionally, a set scaling factor {Yoff, Cboff, Croff} can be applied.
32.6.9 Two Dimension Scaler
The High End Overlay (HEO) data path includes a hardware scaler that allows an image resize in both horizontal
and vertical directions.
32.6.9.1 Video Scaler Description
The scaling operation is based on a vertical and horizontal resampling algorithm. The sampling rate of the original
image is increased when the video is upscaled, and decreased when the video is downscaled. A Vertical
resampler is used to perform a vertical interpolation by a factor of vI, and a decimation by a factor of vD. A
Horizontal resampler is used to perform a vertical interpolation by a factor of hI, and a decimation by a factor of hD.
Both horizontal and vertical low pass filters are designed to minimize the aliasing effect. The frequency response
of the low pass filter has the following characteristics:
H(ω)
=
^I



when 0 ≤ ω ≤ min(^π-_I-,_D-^π--)
0 otherwise
Taking into account the linear phase condition and anticipating the filter length M, the desired frequency response
is modified.
H(ω)
=



I
–jω
e
M_-2---


when 0 ≤ ω ≤ min(^π-_I-,_D-^π--)
0 otherwise
Figure 32-6. Video Resampler Architecture
Input
video
stream
Vertical Resampler
Vertical
upsampler
vI
Low Pass
Filter
Vertical
downsampler
vD
Horizontal Resampler
Horizontal
upsampler
hI
Low Pass
Filter
Horizontal
downsampler
hD
output
video
stream
The impulse response of the low pass filter defined is:
h(n)
=



I
×
ω_-----c
π
when
n
=
0




I
×
ω_-----c
π
×
-s--i--n--_ω-⁽---^ω_c---_n-^c---ⁿ---⁾
otherwise
SAMA5D4 Series [DATASHEET]
Atmel-11238A-ATARM-SAMA5D4-Datasheet_30-Sep-14
655