IPSR-VIDEO Altera, IPSR-VIDEO Datasheet - Page 140

• 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

5–60
Video and Image Processing Suite User Guide
f
In summary, you can generate a set of coefficients for an N-tap, P-phase instance of
the Scaler as follows:
1. Define a function, f(x) over the domain [0, N – 1] under the assumption that
2. For each tap t Î {0, 1, . . . ,N – 1} and for each phase p
3. Quantize each sample. Ideally, the sum of the quantized values for all phases
4. Either store these in a CSV file and copy them into the parameter editor, or load
Coefficients for the bicubic algorithm are calculated using Catmull-Rom splines to
interpolate between values in tap 1 and tap 2.
For more information about the mathematics for Catmull-Rom splines refer to E
Catmull and R Rom. A class of local interpolating splines. Computer Aided Geometric Design,
pages 317–326, 1974.
The bicubic method does not use the preceding steps, but instead obtains weights for
each of the four taps to sample a cubic function that runs between tap 1 and tap 2 at a
position equal to the phase variable described previously. Consequently, the bicubic
coefficients are good for up scaling, but not for down scaling.
If the coefficients are symmetric and provided at compile time, then only half the
number of phases are stored. For N taps and P phases, an array, C[P][N], of quantized
coefficients is symmetric if:
That is, phase 1 is phase P – 1 with the taps in reverse order, phase 2 is phase P – 2
reversed and so on. The predefined Lanczos and bicubic coefficient sets satisfy this
property. Selecting Symmetric for a coefficients set on the Coefficients page in the
parameter editor, forces the coefficients to be symmetric.
Recommended Parameters
In polyphase mode, you must choose parameters for the Scaler MegaCore function
carefully to get the best image quality.
Incorrect parameters can cause a decrease in image quality even as the resource usage
increases. The parameters which have the largest effect are the number of taps and the
filter function chosen to provide the coefficients. The number of phases and number
of bits of precision are less important to the image quality.
(N – 1)/2 is the mid-point of the filter.
sample f(t – p).
should be equal.
them at run time using the control interface.
for all p Π[1, P Р1] and for all t Π[0, N Р1], C[p][t] = C[P Рp][N Р1 Рt]
{0, 1/P, . . . , (P – 1/P)},
Chapter 5: Functional Descriptions
January 2011 Altera Corporation
Scaler