File size: 2,169 Bytes
aeea03d |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 |
"""
NOTE: Major TOM standard does not require any specific type of thumbnail to be computed.
Instead these are shared as optional help since this is how the Core dataset thumbnails have been computed.
"""
from rasterio.io import MemoryFile
from PIL import Image
import numpy as np
def s2l1c_thumbnail(B04, B03, B02, gain=1.3, gamma=0.6):
"""
Takes B04, B03, B02 numpy arrays along with the corresponding NODATA values (default is -32768.0)
Returns a numpy array with the thumbnail
"""
# concatenate
thumb = np.stack([B04, B03, B02], -1)
# apply gain & gamma
thumb = gain*((thumb/10_000)**gamma)
return (thumb.clip(0,1)*255).astype(np.uint8)
def s2l1c_thumbnail_from_datarow(datarow):
"""
Takes a datarow directly from one of the data parquet files
Returns a PIL Image
"""
# red
with MemoryFile(datarow['B04'][0].as_py()) as mem_f:
with mem_f.open(driver='GTiff') as f:
B04=f.read().squeeze()
B04_NODATA = f.nodata
# green
with MemoryFile(datarow['B03'][0].as_py()) as mem_f:
with mem_f.open(driver='GTiff') as f:
B03=f.read().squeeze()
B03_NODATA = f.nodata
# blue
with MemoryFile(datarow['B02'][0].as_py()) as mem_f:
with mem_f.open(driver='GTiff') as f:
B02=f.read().squeeze()
B02_NODATA = f.nodata
img = s2l1c_thumbnail(B04,B03,B02)
return Image.fromarray(img)
if __name__ == '__main__':
from fsspec.parquet import open_parquet_file
import pyarrow.parquet as pq
print('[example run] reading file from HuggingFace...')
url = "https://huggingface.co/datasets/Major-TOM/Core-S2L1C/resolve/main/images/part_01000.parquet"
with open_parquet_file(url, columns = ["B04", "B03", "B02"]) as f:
with pq.ParquetFile(f) as pf:
first_row_group = pf.read_row_group(1, columns = ["B04", "B03", "B02"])
print('[example run] computing the thumbnail...')
thumbnail = s2l1c_thumbnail_from_datarow(first_row_group)
thumbnail.save('example_thumbnail.png', format = 'PNG') |