2. Background
1
Most common mistake is
blurring of moving objects or
by camera-shake.
Blurred image
Dark image
Increase shutter speed
Sensitivity of the sensor has been
improved.
But, we still have dark images
with fast shutter speed.
3. Low-Light Image Enhancement
2
Take photo
under
low-lightscene
Proposed Image EnhancementLow-Light Image Enhancement is
highly demanded.
We propose a gradient-
based low-light image
enhancement.
6. Example of post-processing
5
Input image Processed image
×1.5
Intensity range of
processed image
exceeds [0,255]
Rescaling Intensity clipping Proposed
7. Proposed Integration
6
Shibata, Gradient-Domain Image Reconstruction Framework with Intensity-Range and Base-Structure
Constraints, CVPR2016
Gradient
extraction
Gradient
manipulation
Proposed
integration
Input
image
Output
image
Intensity range
information
𝐹𝐹 𝑢𝑢 𝑥𝑥 = � �
𝑑𝑑=ℎ,𝑣𝑣
𝜕𝜕𝑑𝑑 𝑢𝑢 𝑥𝑥 − 𝑞𝑞𝑑𝑑 𝑥𝑥 2
𝑑𝑑𝑑𝑑 + G𝑅𝑅[𝑢𝑢(𝑥𝑥)]
𝑢𝑢 𝐱𝐱
𝑔𝑔𝑅𝑅(𝑢𝑢 𝐱𝐱 )
𝑅𝑅 𝑚𝑚𝑚𝑚 𝑚𝑚 𝑅𝑅 𝑚𝑚𝑚𝑚𝑚𝑚
Intensity range
We penalize if the
intensity exceeds the
intensity range.This cost function means to
preserving the gradient
information while keeping
the intensity range within the
given intensity range.
14. Conclusions
13
We propose have a gradient-based low-light
image enhancement.
• Higher gain for darker region
• Image integration with
intensity range constraint
Input image
Proposed result
matlab code is available on our project page:
http://www.ok.sc.e.titech.ac.jp/res/IC/LowLight/