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https://github.com/Algy/fast-slic
20x Real-time superpixel SLIC Implementation with CPU
https://github.com/Algy/fast-slic
blazingly-fast image-segmentation python slic superpixel-algorithms superpixels
Last synced: about 1 month ago
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20x Real-time superpixel SLIC Implementation with CPU
- Host: GitHub
- URL: https://github.com/Algy/fast-slic
- Owner: Algy
- License: mit
- Created: 2019-04-09T15:43:41.000Z (over 5 years ago)
- Default Branch: master
- Last Pushed: 2021-09-08T01:13:39.000Z (over 3 years ago)
- Last Synced: 2024-08-02T05:12:06.275Z (4 months ago)
- Topics: blazingly-fast, image-segmentation, python, slic, superpixel-algorithms, superpixels
- Language: C++
- Homepage:
- Size: 2.08 MB
- Stars: 257
- Watchers: 6
- Forks: 34
- Open Issues: 23
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
- awesome-blazingly-fast - fast-slic - 20x Real-time superpixel SLIC Implementation with CPU (C++)
README
# Fast Slic
Fast-slic is a SLIC-variant algorithm implementation that aims for significantly low runtime with cpu. It runs 7-20 times faster than existing SLIC implementations. Fast-slic can process 1280x720 image stream at 60fps.
It started as a part of my hobby project that demanded true "real time" capability in video stream processing. Among pipelines of it was a postprocessing pipeline smoothing the result of image with SLIC superpixels and CRF. Unfortunately, there were no satisfying library for real-time(>30fps) goal. [gSLICr](https://github.com/carlren/gSLICr) was the most promising candidate, but I couldn't make use of it due to limited hardware and inflexible license of CUDA. Therefore, I made the blazingly fast variant of SLIC using only CPU.
[Paper preprint](https://github.com/Algy/fast-slic/files/4009304/fastslic.pdf)
## Demo
## Installation
```python
pip install fast_slic
```
## Basic Usage
```python
import numpy as np
from fast_slic import Slic
from PIL import Image
with Image.open("fish.jpg") as f:
image = np.array(f)
# import cv2; image = cv2.cvtColor(image, cv2.COLOR_RGB2LAB) # You can convert the image to CIELAB space if you need.
slic = Slic(num_components=1600, compactness=10)
assignment = slic.iterate(image) # Cluster Map
print(assignment)
print(slic.slic_model.clusters) # The cluster information of superpixels.
```
If your machine has AVX2 instruction set, you can make it three times faster using `fast_slic.avx2.SlicAvx2` class instead of `fast_slic.Slic`. Haswell and newer Intel cpus, Excavator, and Ryzen support this.
```python
import numpy as np
# Much faster than the standard class
from fast_slic.avx2 import SlicAvx2
from PIL import Image
with Image.open("fish.jpg") as f:
image = np.array(f)
# import cv2; image = cv2.cvtColor(image, cv2.COLOR_RGB2LAB) # You can convert the image to CIELAB space if you need.
slic = SlicAvx2(num_components=1600, compactness=10)
assignment = slic.iterate(image) # Cluster Map
print(assignment)
print(slic.slic_model.clusters) # The cluster information of superpixels.
```
If your machine is ARM with NEON instruction set, which is commonly supported by recent mobile devices and even Raspberry Pi, you can make it two-fold faster by using `fast_slic.neon.SlicNeon` class instead of the original one.
## Performance
With max iteration set to 10, run times of slic implementations for 640x480 image are as follows:
| Implementation | Run time(ms) |
| ----------------------------------------- | --------------:|
| skimage.segment.slic | 216ms |
| cv2.ximgproc.createSuperpixelSLIC.iterate | 142ms |
| fast_slic.Slic(single core build) | 20ms |
| fast_slic.avx2.SlicAvx2(single core build /w avx2 support) | 12ms |
| **fast_slic.Slic(w/ OpenMP support)** | **8.8ms** |
| **fast_slic.avx2.SlicAvx2(w/ OpenMP, avx2 support)** | **5.6ms** |
(RGB-to-CIELAB conversion time is not included. Tested with Ryzen 2600x 6C12T 4.0Hz O.C.)
## Known Issues
* Windows build is quite slower compared to those of linux and mac. Maybe it is due to openmp overhead?
## Tips
* It automatically removes small isolated area of pixels at cost of significant (but not huge) overhead. You can skip denoising process by setting `min_size_factor` to 0. (e.g. `Slic(num_components=1600, compactness=10, min_size_factor=0)`). The setting makes it 20-40% faster.
* To push to the limit, compile it with `FAST_SLIC_AVX2_FASTER` flag and get more performance gain. (though performance margin was small in my pc)
## TODO
- [ ] Publish as a research paper
- [x] Remove or merge small blobs
- [x] Include simple CRF utilities
- [x] Add tests
- [x] Windows build
- [x] More scalable parallel loop in cluster assignment. I suspect there is false sharing problem in the loop.
- [x] would be great if I can optimize loop more. SIMD?