Public Version
Camera ISP Functional Description
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If edge enhancement is selected, the two left-most and two right-most pixels in each line are not outputted
to the line memories and the vertical stage. The
[11:0] HORZ register is the final output
width, up to 1280 pixels when vertical 4-tap mode is used, and up to 640 pixels when vertical 7-tap mode
is used. When edge enhancement is enabled, the horizontal resizer output width used to calculate the
required input width must be
[11:0] HORZ + 4.
NOTE:
Some details of this feature are not available in the public domain,
[7:0] CORE is in U8Q0.
[11:8] SLOP is in U4Q4.
[15:12] GAIN is in
U4Q4.
6.4.8 Camera ISP Statistics Collection Modules
The statistics-collection modules (SCMs) are the H3A and histogram modules that provide statistics on the
incoming images to help designers of camera systems.
6.4.8.1
Camera ISP H3A
6.4.8.1.1 Camera ISP H3A Features
The H3A module supports control loops for autofocus, auto white balance, and auto exposure by
collecting metrics about the imaging/video data. The metrics are used to adjust parameters for processing
the imaging/video data. There are two main blocks in the H3A module:
•
Autofocus engine (AF):
The AF submodule extracts and filters the red, green, and blue data from input image data and
provides the accumulation or peaks of the data in a specified region. The specified region is a
two-dimensional block of data referred to as a paxel. The AF engine supports the following features:
–
Peak mode in a paxel (a paxel is defined as a two dimensional block of pixels): Accumulate the
maximum focus value of each line in a paxel.
–
Accumulation of the maximum focus value of each line in a paxel
–
Accumulation mode
–
Accumulation/sum mode (instead of peak mode): Accumulation of focus value in a paxel
–
Up to 36 paxels/windows in the horizontal direction and up to 128 paxels/windows in the vertical
direction
–
Programmable width and height for the paxel/window
–
Programmable red, green, and blue position within a 2x2 matrix
–
Separate horizontal start for paxel and filtering
–
Programmable vertical line increments within a paxel
–
Parallel IIR filters configured in a dual-biquad configuration with individual coefficients (2 filters with
11 coefficients each)
•
Auto exposure and auto white balance engine (AE/AWB)
The AE/AWB engine accumulates values and checks for saturated values in a subsampling of the
video data. In the case of the AE/AWB, the two-dimensional block of data is referred to as a window.
Thus, other than having different names, paxels and windows are essentially the same. However, the
numbers, dimensions, and starting positions of AF paxels and AE/AWB windows are programmable
separately. AE/AWB supports the following features:
–
Accumulation of clipped pixels along with all nonsaturated pixels
–
Up to 36 horizontal windows/paxel and up to 128 vertical windows/paxel
–
Separate vertical start coordination and height for a black row of paxels different from the remaining
color paxels
–
Programmable horizontal and vertical sampling points in a window
NOTE:
Some details of this feature are not available in the public domain.
1224
Camera Image Signal Processor
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated
