
TM1100 Preliminary Data Book
Philips Semiconductors
13-24
PRELIMINARY INFORMATION
File: icp.fm5, modified 7/26/99
13.6.9
Vertical Filter - SDRAM to SDRAM
This routine performs vertical scaling and filtering of one
component (Y, U or V) of an N x M image from one loca-
tion in SDRAM to another.
13.6.9.1
Algorithms
The routine reads image data from SDRAM using the Y
address counter, scales and filters the data in the vertical
direction and writes it back to the SDRAM using the Z ad-
dress counter. The 5-tap filter scales and filters the data.
The U LSB register is used as the scaling coefficient reg-
ister. The U LSB Increment value supplied by the param-
eter table determines the scaling. Lines at the top and
bottom of the image are mirrored to provide the extra line
data needed by the 5-tap filter.
The routine reads and writes data in 64-byte (one
SDRAM block) columns of pixels until the entire image is
transferred. For each column, line segments of 64 pixels
are processed until the entire column has been pro-
cessed. Each 64-pixel line segment generated requires
five vertically adjacent 64-pixel line segments as input to
the 5-tap filter. The routine processes the image in pixel
columns to eliminate redundant read of input pixel data:
each new line segment typically requires reading only
one new 64 byte line segment.
The routine processes data in 64-pixel blocks, corre-
sponding to the input block buffer sizes. Five buffers are
used in processing the current line segment, while the
sixth buffer reads in the next line segment in overlap with
current processing.
13.6.9.2
Parameter Table
the input and output starting addresses and offsets, the
image height in lines and width in pixels, and the scale
factor.
0
1234 5
6 7 8 9 10 11 12 13 14 15 16 17 18 1920
0
1234 5
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
P2N = F(10, 11, 12, 13, 14)
P2L = F(2, 7, 12, 17, 22)
21 22 23 24 25
Normal Down Scaling
Large Down Scaling
Input Pixels
Output Pixels
Input Pixels
Output Pixels
Figure 13-18. Normal vs. Large Down Scaling for Scale Factor = 5.0
Figure 13-19. Vertical Filter Parameter Table
Parameter Word
Description
Upper 2 bytes
Lower 2 bytes
Input Image Start Address
Start address of X0Y0 (byte address)
U Counter
Start Fraction
Input Image
Line Offset
Starting value: may be 0.5, etc. for interspersed convert;
Line offset from X0Y0 to X0Y1