Changeset 2005Tweet

Timestamp:

Nov 17, 2007, 12:35:59 PM (13 years ago)

Author:

Sam Hocevar

Message:

• Nicer colour pattern.

Location:

www/study

Files:

• part5.html (modified) (1 diff)
• pat5-1-2.png (modified) (previous)
• study.py (modified) (1 diff)

www/study/part5.html

@@ -68 +68 @@
 <h3> 5.2. Accounting for other dimensions </h3>
 
-<p> The following patterns shows three ways to dither the same colour
-using our 8-colour palette. The first one mixes black, yellow and white
-pixels. The second one mixes red, green and cyan pixels. The last one
-mixes red, green and magenta pixels. But they all visually blend to the
-same colour: </p>
+<p> The following patterns show four ways to dither the same colour using
+our 8-colour palette. The first one mixes black, red and white pixels. The
+second one mixes black, red and cyan pixels. The third mixes black, red, green
+and magenta pixels. The last one mixes black, red, green and blue pixels. But
+all patterns visually blend to the same shade: </p>
 
 <p style="text-align: center;">
-  <img src="pat5-1-2.png" width="240" height="160"
+  <img src="pat5-1-2.png" width="320" height="160"
        class="inline" alt="3 ways to dither the same colour" />
 </p>

www/study/study.py

@@ -536 +536 @@
 
 # Pattern 5.1.2: different colours give the same result
-dest = Image((240, 160))
+dest = Image((320, 160))
 for x in range(80):
     for y in range(80):
-        r = DITHER_BAYER44[(y / 4) % 4][(x / 4) % 4] > 7
-        g = DITHER_BAYER44[(y / 4) % 4][(x / 4) % 4] > 13
-        b = DITHER_BAYER44[(y / 4) % 4][(x / 4) % 4] > 7
+        r = DITHER_BAYER44[(y / 8) % 4][(x / 8) % 4] > 7
+        g = DITHER_BAYER44[(y / 8) % 4][(x / 8) % 4] > 13
+        b = DITHER_BAYER44[(y / 8) % 4][(x / 8) % 4] > 13
         dest.setRgb(x, y, r, b, g)
     for y in range(80, 160):
         r = DITHER_BAYER44[y % 4][x % 4] > 7
         g = DITHER_BAYER44[y % 4][x % 4] > 13
-        b = DITHER_BAYER44[y % 4][x % 4] > 7
+        b = DITHER_BAYER44[y % 4][x % 4] > 13
         dest.setRgb(x, y, r, b, g)
 for x in range(80, 160):
     for y in range(80):
-        r = DITHER_BAYER44[(y / 4) % 4][(x / 4 + 1) % 4] > 7
-        g = DITHER_BAYER44[(y / 4) % 4][(x / 4) % 4] > 13
-        b = DITHER_BAYER44[(y / 4) % 4][(x / 4) % 4] > 7
+        r = DITHER_BAYER44[(y / 8) % 4][(x / 8) % 4] > 7
+        g = DITHER_BAYER44[(y / 8) % 4][(x / 8 + 1) % 4] > 13
+        b = DITHER_BAYER44[(y / 8) % 4][(x / 8 + 1) % 4] > 13
         dest.setRgb(x, y, r, b, g)
     for y in range(80, 160):
-        r = DITHER_BAYER44[y % 4][(x + 1) % 4] > 7
-        g = DITHER_BAYER44[y % 4][x % 4] > 13
-        b = DITHER_BAYER44[y % 4][x % 4] > 7
+        r = DITHER_BAYER44[y % 4][x % 4] > 7
+        g = DITHER_BAYER44[y % 4][(x + 1) % 4] > 13
+        b = DITHER_BAYER44[y % 4][(x + 1) % 4] > 13
         dest.setRgb(x, y, r, b, g)
 for x in range(160, 240):
     for y in range(80):
-        r = DITHER_BAYER44[(y / 4 + 1) % 4][(x / 4 + 1) % 4] > 7
-        g = DITHER_BAYER44[(y / 4) % 4][(x / 4) % 4] > 13
-        b = DITHER_BAYER44[(y / 4 + 1) % 4][(x / 4) % 4] > 7
+        r = DITHER_BAYER44[(y / 8 + 1) % 4][(x / 8 + 1) % 4] > 7
+        g = DITHER_BAYER44[(y / 8) % 4][(x / 8) % 4] > 13
+        b = DITHER_BAYER44[(y / 8 + 1) % 4][(x / 8) % 4] > 13
         dest.setRgb(x, y, r, b, g)
     for y in range(80, 160):
         r = DITHER_BAYER44[(y + 1) % 4][(x + 1) % 4] > 7
         g = DITHER_BAYER44[y % 4][x % 4] > 13
-        b = DITHER_BAYER44[(y + 1) % 4][x % 4] > 7
+        b = DITHER_BAYER44[(y + 1) % 4][x % 4] > 13
+        dest.setRgb(x, y, r, b, g)
+for x in range(240, 320):
+    for y in range(80):
+        r = DITHER_BAYER44[(y / 8 + 1) % 4][(x / 8) % 4] > 7
+        g = DITHER_BAYER44[(y / 8) % 4][(x / 8) % 4] > 13
+        b = DITHER_BAYER44[(y / 8) % 4][(x / 8 + 2) % 4] > 13
+        dest.setRgb(x, y, r, b, g)
+    for y in range(80, 160):
+        r = DITHER_BAYER44[(y + 1) % 4][x % 4] > 7
+        g = DITHER_BAYER44[y % 4][x % 4] > 13
+        b = DITHER_BAYER44[y % 4][(x + 2) % 4] > 13
         dest.setRgb(x, y, r, b, g)
 dest.writePng("pat5-1-2.png")