Some encode/decode practice.

src/image/ImagePrimitives.h

@@ -23,4 +23,19 @@ public:
             }
         }
     }
+
+    static void drawAlternatingStrips(std::vector<unsigned char>& data, unsigned width, unsigned height, unsigned channels, unsigned bytesPerRow)
+    {
+        for(unsigned jdx=0;jdx<height;jdx++)
+        {
+            const auto heightOffset = jdx*bytesPerRow;
+            for(unsigned idx=0;idx<width*channels;idx+=channels)
+            {
+                const auto index = heightOffset + idx;
+                data[index] = (idx%2 == 0) ? 255*jdx/(height+1) : 0;
+                data[index+1] = 0;
+                data[index+2] = 0;
+            }
+        }
+    }
 };