Enhance
Raster data often lacks the vibrant colors typically seen in natural imagery because it does not use the standard 8-bit resolution that computer monitors are designed to display. As a result, raw images often appear nearly black and white with little visible detail. To create natural-colored images, various image enhancement techniques must be applied. The SIPT library implements the algorithm used to create the Sentinel-2 L2A True Color Optimized images. The original description can be found [here]{https://custom-scripts.sentinel-hub.com/custom-scripts/sentinel-2/l2a_optimized/}. The algorithm includes the following steps:
- Highlight Compression
- Gamma Correction
- Saturation Boost
- sRGB convertion
The sRGB convertion is intentionally not implemented. There is no need to change the color space.
Parameters¤
| Name | Type | Description |
|---|---|---|
input_dir |
str |
Input directory containing GeoTIFF files. Can contain subfolders. |
output_dir |
str |
Output directory. If same as input then the original files are overwritten. Keeps subfolders. |
alpha |
boolean |
Choose whether to add an alpha channel to the enhanced images for transparency or not. Default: True |
max_reflectance |
float |
Define the max reflectance used in highlight compression. Typical reflectance values fall between 0 and 1. Outliers are possible depending on the used image sensors. Default: 3.0 |
min_reflectance |
float |
Define the min reflectance used in highlight compression. Typical reflectance values fall between 0 and 1. Outliers are possible depending on the used image sensors. Default: 0.13 |
sat |
float |
Adjust the saturation. 1 is no change, < 1 reduces the saturation and > 1 increases the saturation. Default: 1.6 |
gamma |
float |
The gamma correction factor that controls the non-linear mapping of intensity values (contrast). Default: 1.8 |
gOff |
float |
An offset applied before and after the gamma adjustment, affecting the curve's shape and how the lower intensities are mapped. Default: 0.01 |