brother_ql_create --red speedup (saving 90% CPU time)

The dissection of the color into red, black, & white now
takes part in the HSV color space (instead of HLS before).
Pillow's built-in capabilities to convert RGB → HSV
are now used.

While the creation of --red labels still takes 16 times longer
than the simple black/white ones, it is now 90% less time than
before this commit.

brother_ql/brother_ql_create.py

@@ -10,7 +10,7 @@ import PIL.ImageOps, PIL.ImageChops
 from brother_ql.raster import BrotherQLRaster
 from brother_ql.devicedependent import models, label_type_specs, ENDLESS_LABEL, DIE_CUT_LABEL, ROUND_DIE_CUT_LABEL
 from brother_ql import BrotherQLError, BrotherQLUnsupportedCmd, BrotherQLUnknownModel
-from brother_ql.image_trafos import filtered_hls
+from brother_ql.image_trafos import filtered_hsv
 
 try:
     stdout = sys.stdout.buffer
@@ -104,18 +104,18 @@ def create_label(qlr, image, label_size, threshold=70, cut=True, dither=False, c
         im = new_im
 
     if red:
-        filter_h = lambda h: 255 if h <  60 or h > 240 else 0
-        filter_l = lambda l: 255 if l < 220 else 0
+        filter_h = lambda h: 255 if (h <  40 or h > 210) else 0
         filter_s = lambda s: 255 if s > 100 else 0
-        red_im = filtered_hls(im, filter_h, filter_l, filter_s)
+        filter_v = lambda v: 255 if v >  80 else 0
+        red_im = filtered_hsv(im, filter_h, filter_s, filter_v)
         red_im = red_im.convert("L")
         red_im = PIL.ImageOps.invert(red_im)
         red_im = red_im.convert("1", dither=Image.NONE)
 
         filter_h = lambda h: 255
-        filter_l = lambda l: 255 if l < 120 else 0
         filter_s = lambda s: 255
-        black_im = filtered_hls(im, filter_h, filter_l, filter_s)
+        filter_v = lambda v: 255 if v <  80 else 0
+        black_im = filtered_hsv(im, filter_h, filter_s, filter_v)
         black_im = black_im.convert("L")
         black_im = PIL.ImageOps.invert(black_im)
         black_im = black_im.convert("1", dither=Image.NONE)

brother_ql/image_trafos.py

@@ -1,49 +1,23 @@
 from PIL import Image
 import colorsys
 
-def HLSColor(img):
+def filtered_hsv(im, filter_h, filter_s, filter_v, default_col=(255,255,255)):
     """ https://stackoverflow.com/a/22237709/183995 """
-    if isinstance(img,Image.Image):
-        img = img.convert('RGB')
-        r,g,b = img.split()
-        Hdat = []
-        Ldat = []
-        Sdat = []
-        for rd,gn,bl in zip(r.getdata(),g.getdata(),b.getdata()) :
-            h,l,s = colorsys.rgb_to_hls(rd/255.,gn/255.,bl/255.)
-            Hdat.append(int(h*255.))
-            Ldat.append(int(l*255.))
-            Sdat.append(int(s*255.))
-        r.putdata(Hdat)
-        g.putdata(Ldat)
-        b.putdata(Sdat)
-        return Image.merge('RGB',(r,g,b))
-    else:
-        return None
 
-def filtered_hls(im, filter_h, filter_l, filter_s, default_col=(255,255,255)):
-    hls_im = HLSColor(im)
-
-    H, L, S = 0, 1, 2
-    hls = hls_im.split()
-    mask_h = hls[H].point(filter_h)
-    mask_l = hls[L].point(filter_l)
-    mask_s = hls[S].point(filter_s)
+    hsv_im = im.convert('HSV')
+    H, S, V = 0, 1, 2
+    hsv = hsv_im.split()
+    mask_h = hsv[H].point(filter_h)
+    mask_s = hsv[S].point(filter_s)
+    mask_v = hsv[V].point(filter_v)
 
     Mdat = []
-    # for debugging:
-    #mask_h, mask_l, mask_s = hls_im.split()
-    seen = []
-    for h, l, s in zip(mask_h.getdata(), mask_l.getdata(), mask_s.getdata()):
-        if (h, l, s) not in seen:
-            seen.append((h, l, s))
-            #print((h, l, s))
-        Mdat.append(255 if (h and l and s) else 0)
+    for h, s, v in zip(mask_h.getdata(), mask_s.getdata(), mask_v.getdata()):
+        Mdat.append(255 if (h and s and v) else 0)
 
     mask = mask_h
     mask.putdata(Mdat)
 
-    filtered_im = Image.new("RGB", hls_im.size, color=default_col)
+    filtered_im = Image.new("RGB", im.size, color=default_col)
     filtered_im.paste(im, None, mask)
     return filtered_im
-