AP0101CS datasheet(18/42 Pages) ONSEMI

18 / 42 page

AP0101CS/D Rev. 7, 1/16 EN

©Semiconductor Components Industries, LLC,2016.

AP0101CS HDR: Image Signal Processor (ISP)

Image Flow Processor

Defect Correction

After data decompanding the image stream processing starts with defect correction.

To obtain defect free images, the pixels marked defective during sensor readout and the

pixels determined defective by the defect correction algorithms are replaced with values

derived from the non-defective neighboring pixels. This image processing technique is

called defect correction.

AdaCD (Adaptive Color Difference)

Automotive applications require good performance in extremely low light, even at high

temperature conditions. In these stringent conditions the image sensor is prone to

higher noise levels, and so efficient noise reduction techniques are required to circum-

vent this sensor limitation and deliver a high quality image to the user.

The AdaCD Noise Reduction Filter is able to adapt its noise filtering process to local

image structure and noise level, removing most objectionable color noise while

preserving edge details.

Black Level Subtraction and Digital Gain

After noise reduction, the pixel data goes through black level subtraction and multiplica-

tion of all pixel values by a programmable digital gain. Independent color channel digital

gain can be adjusted with registers. Black level subtract (to compensate for sensor data

pedestal) is a single value applied to all color channels. If the black level subtraction

produces a negative result for a particular pixel, the value of this pixel is set to 0.

Positional Gain Adjustments (PGA)

Lenses tend to produce images whose brightness is significantly attenuated near the

edges. There are also other factors causing fixed pattern signal gradients in images

captured by image sensors. The cumulative result of all these factors is known as image

shading. The AP0101CS has an embedded shading correction module that can be

programmed to counter the shading effects on each individual R, Gb, Gr, and B color

signal.

The Correction Function

The correction functions can then be applied to each pixel value to equalize the

response across the image as follows:

(EQ 1)

where P are the pixel values and f is the color dependent correction functions for each

color channel.

Pcorrected row, col



Psensor row, col

 f(row, col)



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