Improve image_display.md

modules/image_display.md

@@ -23,6 +23,9 @@ layout:    page
 ```
 brightness = ( value - min ) / ( max - min )
 
+if ( brightness < 0 ) set to zero
+if ( brightness > 1 ) set to one
+
 0 <= brightness <= 1
 
 contrast = max - min
@@ -31,8 +34,15 @@ contrast = max - min
 ## Activity
 
 * Open image: xy_8bit__nuclei_noisy_different_intensity.tif
-* Explore different LUTs and LUT settings
-        * Appreciate that LUT settings do not affect image content.
+* Explore different single color LUTs and LUT settings
+* Appreciate that LUT settings do not change the pixel values
+
+## Optional activity: Multi color LUTs
+
+* Open image: xy_16bit__nuclei_high_dynamic_range 
+* Appreciate that a single color LUT does not suffice
+* Explore color LUTs
+* Add a LUT calibration bar to the image
 
 
 ## Formative Assessment