3 added 126 characters in body
source | link
Graphics[{
  PointSize[.025], {Hue[3 #3], Point[{#1, #2}]} & @@@ a, 
  Text["noisy", {0, 1}, {1, 1}], Text["quiet", {0, 2}, {1, 1}]}, 
  AspectRatio -> 1/2]

Mathematica graphics

or

ArrayPlot[1/Array[GCD, {50, 50}],
  ColorFunction -> "Rainbow", ColorFunctionScaling -> True]

Mathematica graphics

Graphics[{
  PointSize[.025], {Hue[3 #3], Point[{#1, #2}]} & @@@ a, 
  Text["noisy", {0, 1}, {1, 1}], Text["quiet", {0, 2}, {1, 1}]}, 
  AspectRatio -> 1/2]

or

ArrayPlot[1/Array[GCD, {50, 50}],
  ColorFunction -> "Rainbow", ColorFunctionScaling -> True]
Graphics[{
  PointSize[.025], {Hue[3 #3], Point[{#1, #2}]} & @@@ a, 
  Text["noisy", {0, 1}, {1, 1}], Text["quiet", {0, 2}, {1, 1}]}, 
  AspectRatio -> 1/2]

Mathematica graphics

or

ArrayPlot[1/Array[GCD, {50, 50}],
  ColorFunction -> "Rainbow", ColorFunctionScaling -> True]

Mathematica graphics

2 added 112 characters in body
source | link
Graphics[{
  PointSize[.025], {Hue[3 #3], Point[{#1, #2}]} & @@@ a, 
  Text["noisy", {0, 1}, {1, 1}], Text["quiet", {0, 2}, {1, 1}]}, 
  AspectRatio -> 1/2]

or

ArrayPlot[1/Array[GCD, {50, 50}],
  ColorFunction -> "Rainbow", ColorFunctionScaling -> True]
Graphics[{
  PointSize[.025], {Hue[3 #3], Point[{#1, #2}]} & @@@ a, 
  Text["noisy", {0, 1}, {1, 1}], Text["quiet", {0, 2}, {1, 1}]}, 
  AspectRatio -> 1/2]
Graphics[{
  PointSize[.025], {Hue[3 #3], Point[{#1, #2}]} & @@@ a, 
  Text["noisy", {0, 1}, {1, 1}], Text["quiet", {0, 2}, {1, 1}]}, 
  AspectRatio -> 1/2]

or

ArrayPlot[1/Array[GCD, {50, 50}],
  ColorFunction -> "Rainbow", ColorFunctionScaling -> True]
1
source | link

Graphics[{
  PointSize[.025], {Hue[3 #3], Point[{#1, #2}]} & @@@ a, 
  Text["noisy", {0, 1}, {1, 1}], Text["quiet", {0, 2}, {1, 1}]}, 
  AspectRatio -> 1/2]