Add --band flag

README.md

@@ -29,8 +29,10 @@ near-realtime picture of Earth.
 
 ```
 usage: himawaripy [-h] [--version] [--auto-offset | -o OFFSET]
-                  [-l {4,8,16,20}] [-d DEADLINE] [--save-battery]
-                  [--output-dir OUTPUT_DIR] [--dont-change]
+                  [-l {4,8,16,20}]
+                  [--band {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16}]
+                  [-d DEADLINE] [--save-battery] [--output-dir OUTPUT_DIR]
+                  [--dont-change]
 
 set (near-realtime) picture of Earth as your desktop background
 
@@ -44,14 +46,17 @@ optional arguments:
   -l {4,8,16,20}, --level {4,8,16,20}
                         increases the quality (and the size) of each tile.
                         possible values are 4, 8, 16, 20
+  --band {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16}
+                        If 0, get RGB visible light picture; if 1 to 16, get
+                        just that band as greyscale image. See
+                        https://en.wikipedia.org/wiki/Himawari_8#Instruments.
   -d DEADLINE, --deadline DEADLINE
                         deadline in minutes to download all the tiles, set 0
                         to cancel
   --save-battery        stop refreshing on battery
   --output-dir OUTPUT_DIR
                         directory to save the temporary background image
   --dont-change         don't change the wallpaper (just download it)
-
 ```
 
 Most of the time himawaripy can accurately detect your timezone if you pass the flag `--auto-offset`, although you may

himawaripy/__main__.py

@@ -55,9 +55,9 @@ def calculate_time_offset(latest_date, auto, preferred_offset):
 def download_chunk(args):
     global counter
 
-    x, y, latest, level = args
-    url_format = "https://himawari8-dl.nict.go.jp/himawari8/img/D531106/{}d/{}/{}_{}_{}.png"
-    url = url_format.format(level, WIDTH, strftime("%Y/%m/%d/%H%M%S", latest), x, y)
+    x, y, band, latest, level = args
+    url_format = "https://himawari8-dl.nict.go.jp/himawari8/img/{}/{}d/{}/{}_{}_{}.png"
+    url = url_format.format(band, level, WIDTH, strftime("%Y/%m/%d/%H%M%S", latest), x, y)
 
     tiledata = download(url)
 
@@ -71,7 +71,7 @@ def download_chunk(args):
             print("Downloading tiles: completed.")
         else:
             print("Downloading tiles: {}/{} completed...".format(counter.value, level * level))
-    return x, y, tiledata
+    return x, y, band, tiledata
 
 
 def parse_args():
@@ -105,6 +105,13 @@ def parse_args():
         default=4,
         help="increases the quality (and the size) of each tile. possible values are 4, 8, 16, 20",
     )
+    parser.add_argument(
+        "--band",
+        type=int,
+        choices=range(0, 17),
+        default=0,
+        help="If 0, get RGB visible light picture; if 1 to 16, get just that band as greyscale image. See https://en.wikipedia.org/wiki/Himawari_8#Instruments."
+    )
     parser.add_argument(
         "-d",
         "--deadline",
@@ -192,13 +199,20 @@ def thread_main(args):
     if args.auto_offset or args.offset != 10:
         print("Offset version: {} GMT.".format(strftime("%Y/%m/%d %H:%M:%S", requested_time)))
 
-    png = Image.new("RGB", (WIDTH * level, HEIGHT * level))
+    if args.band > 0:
+        band = "FULL_24h/B{:02d}".format(args.band)
+        image_mode = "LA"
+    else:
+        band = "D531106"
+        image_mode = "RGB"
+
+    png = Image.new(image_mode, (WIDTH * level, HEIGHT * level))
 
     p = mp_dummy.Pool(level * level)
     print("Downloading tiles...")
-    res = p.map(download_chunk, it.product(range(level), range(level), (requested_time,), (args.level,)))
+    res = p.map(download_chunk, it.product(range(level), range(level), (band,), (requested_time,), (args.level,)))
 
-    for (x, y, tiledata) in res:
+    for (x, y, band, tiledata) in res:
         tile = Image.open(io.BytesIO(tiledata))
         png.paste(tile, (WIDTH * x, HEIGHT * y, WIDTH * (x + 1), HEIGHT * (y + 1)))