Fast Open Image Signal Processor (fast-openISP)

As told by its name, fast-openISP is a faster (and bugs-fixed) re-implementation of the openISP project.

Compared to C-style code in the official openISP repo, fast-openISP uses pure matrix implementations based on Numpy, and increases processing speed over 300 times.

Here is the running time in my Ryzen 7 1700 8-core 3.00GHz machine with the 1920x1080 input Bayer array:

Module	openISP	fast-openISP
DPC	20.57s	0.29s
BLC	11.75s	0.02s
AAF	16.87s	0.08s
AWB	7.54s	0.02s
CNF	73.99s	0.25s
CFA	40.71s	0.20s
CCM	56.85s	0.06s
GAC	25.71s	0.07s
CSC	60.32s	0.06s
NLM	1600.95s	5.37s
BNF	801.24s	0.75s
CEH*	-	0.14s
EEH	68.60s	0.24s
FCS	25.07s	0.08s
HSC	56.34s	0.07s
BBC	27.92s	0.03s
End-to-end pipeline	2894.41s	7.82s

^* CEH module is not included in the official openISP pipeline.

Usage

Clone this repo and run

python demo.py

The ISP outputs will be saved to ./output directory.

The only required package for pipeline execution is numpy. opencv-python and scikit-image are required only for data IO.

Algorithms

All modules in fast-openISP reproduce processing algorithms in openISP, except for EEH and BCC modules. In addition, a CEH (contrast enhancement) module with CLAHE is added into the fast-openISP pipeline.

EEH (edge enhancement)

The official openISP uses an asymmetric kernel to extract edge map. In fast-openISP, however, we use the subtraction between the original and the gaussian filtered Y-channel as the edge estimation, which reduces the artifact when the enhancement gain is large.

BCC (brightness & contrast control)

The official openISP enhances the image contrast by pixel-wise enlarging the difference between pixel values and a constant integer (128). In fast-openISP, we use the median value of the whole frame instead of a constant.

Parameters

Tunable parameters in fast-openISP are differently named from those in openISP, but they are all self-explained, and no doubt you can easily tell the counterparts in two repos. All parameters are managed in a yaml in ./configs, one file per camera.

Demo

Bayer Input

CFA Interpolation

Color Correction

Gamma Correction

Non-local Means & Bilateral Filter

Contrast Enhancement

Edge Enhancement

Hue & Saturation Control

Brightness & Contrast Control

License

Copyright 2021 Qiu Jueqin.

Licensed under MIT.