IPSR-VIDEO Altera, IPSR-VIDEO Datasheet - Page 86

• Manufacturer Part Number: IPSR-VIDEO
• Description: RENEWAL Of IPS-VIDEO
• Manufacturer: Altera
• Series: IP Suitesr

Specifications of IPSR-VIDEO

• Software Application: IP CORE, SUITES
• Supported Families: Arria GX, Cyclone II, HardCopy II, Stratix II
• Features: Common Avalon Streaming (Avalon-St) Interface And Avalon-St Video Protocol
• Core Architecture: FPGA
• Core Sub-architecture: Arria, Cyclone, Stratix
• Rohs Compliant: NA
• Lead Free Status / RoHS Status: na

5–6
Chroma Resampler
Video and Image Processing Suite User Guide
Horizontal Resampling (4:2:2)
f
The Chroma Resampler MegaCore function allows you to change between 4:4:4, 4:2:2
and 4:2:0 sampling rates where:
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■
■
All modes of the Chroma Resampler assume the chrominance (chroma) and
luminance (luma) samples are co-sited (that is, their values are sampled at the same
time). The horizontal resampling process supports nearest-neighbor and filtered
algorithms. The vertical resampling process only supports the nearest-neighbor
algorithm.
The Chroma Resampler MegaCore function can be configured to change image size at
run time using control packets.
Figure 5–1
Figure 5–1. Resampling 4.4.4 to a 4.2.2 Image
Conversion from sampling rate 4:4:4 to 4:2:2 and back are scaling operations on the
chroma channels. This means that these operations are affected by some of the same
issues as the Scaler MegaCore function. However, because the scaling ratio is fixed as
2× up or 2× down, the Chroma Resampler MegaCore function is highly optimized for
these cases.
The Chroma Resampler MegaCore Function only supports the cosited form of
horizontal resampling—the form for 4:2:2 data in ITU Recommendation BT.601, MPEG-
2, and other standards.
For more information about the ITU standard, refer to Recommendation ITU-R BT.601,
Encoding Parameters of Digital Television for Studios, 1992, International
Telecommunications Union, Geneva.
4:4:4 to 4:2:2
The nearest-neighbor algorithm is the simplest way to down-scale the chroma
channels. It works by simply discarding the Cb and Cr samples that occur on even
columns (assuming the first column is numbered 1). This algorithm is very fast and
cheap but, due to aliasing effects, it does not produce the best image quality.
4:4:4 specifies full resolution in planes 1, 2, and 3
4:2:2 specifies full resolution in plane 1; half width resolution in planes 2 and 3
4:2:0 specifies full resolution in plane 1; half width and height resolution in planes
2 and 3
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= Y’
= Cb
= Cr
= CbCr
= Y’CbCr
shows the location of samples in a co-sited 4:2:2 image.
Sample No
1
2
3
4
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1
2
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3
4
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5
Chapter 5: Functional Descriptions
January 2011 Altera Corporation
6
Chroma Resampler
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