IBIS4-14000-M Datasheet, PDF (11/30 Pages) Cypress Semiconductor – 14-Megapixel CMOS Image Sensor

IBIS4-14000-M
IBIS4-14000-C
2.3 Readout and Subsampling Modes
The subsampling modes available on the IBIS4-14000 are
summarized in Table 7.
Table 7. Subsampling Modes
Subsampling modes programmed into SPI register
X shift register subsampling settings
Bitcode
Mode
000
1:1
001
Full resolution (all columns)
010
011
24:1
Select 4 columns/ skip 20
100
8:1
Select 4 columns / skip 4s
101
12:1
Select 4 columns / skip 8
Y shift register subsampling settings
Bitcode
Mode
000
4:1
010
Select 2 rows / skip 2
100
001
1:1
Full resolution (all rows)
011
6:1
Select 2 rows / skip 4
101
12:1
Select 2 rows / skip 10
Use
Full resolution (4 outputs)
4:1 subsampling
24:1 subsampling ( 2 outputs)
8:1 subsampling (2 outputs)
12:1 subsampling (2 outputs)
Use
4:1 subsampling
Full resolution
6:1 subsampling
12:1 subsampling
Each mode is selected independently for the X and Y shift
registers. The subsampling mode is configured via the serial
input port of the chip. The Y and X shift registers have some
different subsampling modes, due to constraints in the design
of the chip.
The baseline full resolution operation mode uses 4 outputs to
read out the entire image. 4 consecutive pixels of a row are put
in parallel on the 4 parallel outputs.
Subsampling is implemented by a shift register with
hard-coded subsample modes. Depending on the selected
mode, the shift register skips the required number of pixels
when shifting the row or column pointer.
The X shift register always selects 4 consecutive columns in
parallel. Subsampling in X can be done by activating one of
the modes wherein a multiple of 4 consecutive columns is
skipped on a CLK_X pulse. The Y shift register selects a single
row. It will consecutively select 2 adjacent rows and then skip
an amount of rows set by the subsample mode. This imple-
mentation is chosen for easy subsampling of color images
through a 2-channel readout. In this way color data from 2x2
pixels is made available in all subsample modes. On
monochrome sensors this is not required—only one output
can be used and the each second row selected by the Y shift
register can be skipped. This doubles the frame rate. Note that
for 2 or 1 channel readout, the not-used output amplifiers can
be powered down through the SPI shift register.
Rows can also be skipped by extra CLK_Y pulses. It is not
required to apply additional control pulses to rows that are
skipped. This is a way to implement extra subsampling
schemes. For example, to support the 24:1 X shift register
mode also vertically, the Y shift register can be set to the 12:1
mode and an additional CLK_Y pulse needs to be given at the
start of each row.
Table 8 lists the frame rates of the IBIS4-14000 in various
subsample modes with only one output. The row blanking time
(dead time between readout of successive rows) has been set
to 17.5 s.
Table 8. Frame Rates and Resolution for Various Subsample Modes
Ratio
# Outputs
Image Resolution Frame rate [frames/s]
1:1
4
3024 x 4536
3.25
4:1
1
756 x 1134
12.99
8:1
1
378 x 567
41.30
12:1
1
252 x 378
77.13
Note that the 24 additional columns and rows (see Figure 4) do not subsample.
Frame readout time [s]
0.308
0.077
0.024
0.013
Document #: 38-05709 Rev. *A
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