readme.md

Input

Outputs

Pixel Replacement (aka brute force)

Time: 1.51s Replaced 875566 of 1819797 pixels

Geometry Mask

Time: 0.681s

apply transparency to landsat thumbnail.py

from time import time
from PIL import Image, ImageDraw


def by_geometry_mask():
    def to_percentage(coordinates, extent):
        min_x, min_y, max_x, max_y = extent
        points = []
        for x, y in coordinates:
            px = (x - min_x) / (max_x - min_x)
            py = (y - min_y) / (max_y - min_y)
            points.append((px, py))
        return points

    POINTS = to_percentage([[-3.207, 81.203], [2.307, 79.699], [-5.129, 78.838], [-11.194, 80.211], [-3.207, 81.203]], (-11.194, 78.838, 2.307, 81.203))
    SCALE_FACTOR = 4

    print('Geometry Mask:')
    t = time()
    img = Image.open('LC80010022016230LGN00_thumb_large.jpg')  # type: Image.Image

    w, h = img.size[0] * SCALE_FACTOR, img.size[1] * SCALE_FACTOR

    mask = Image.new('L', (w, h), 255)

    draw = ImageDraw.Draw(mask)
    draw.polygon(list(map(lambda p: (p[0] * w, p[1] * h), POINTS)), fill=0)

    # mask = ImageOps.invert(mask)
    mask = mask.resize(img.size, resample=Image.ANTIALIAS)

    img = img.convert('P', palette=Image.ADAPTIVE)
    img.paste(0, mask=mask)
    img.save('by geometry mask.png')
    print('    Done in {:.3}s'.format(time() - t))
    print()


def by_pixel_replacement():
    print('Pixel Replacement:')
    t = time()

    img = Image.open('LC80010022016230LGN00_thumb_large.jpg')  # type: Image.Image
    img = img.convert('RGBA')

    pixels = list(img.getdata())
    dropped = 0
    total = len(pixels)
    for i, (r, g, b, a) in enumerate(pixels):
        if r < 15 and g < 15 and b < 15:
            dropped += 1
            pixels[i] = (0, 0, 0, 0)
    img.putdata(pixels)
    img.save('by pixel replacement.png')
    print('    Done in {:0.3}s (replaced {} of {} pixels)'.format(time() - t, dropped, total))
    print()


by_pixel_replacement()
by_geometry_mask()

footprint.geojson

{
  "type": "Feature",
  "properties": {
    "uri": "http://landsat-pds.s3.amazonaws.com/L8/001/002/LC80010022016230LGN00/LC80010022016230LGN00_thumb_large.jpg"
  },
  "geometry": {
    "type": "Polygon",
    "coordinates": [[[-3.207,81.203],[2.307,79.699],[-5.129,78.838],[-11.194,80.211],[-3.207,81.203]]]
  }
}