GIS 6005 - Communicating GIS - Module 4

Color ramp	Notes	Stepwise Intervals
Linear progression		R	G	B
	·         After setting the parameters for the darkest color based on the suggestion, I attempted to make my brightest color comparable in hue. ·         The formula for the R scale progression: 255-150=105 105/5=21 ·         The formula for the G scale progression: 130-0=130 130/5=26 ·         The formula for the B scale progression: 225-75=150        150/5=30	R150 R171 R192 R213 R234 R255	G000 G026 G052 G078 G104 G130	B075 B105 B135 B165 B195 B225
	·
Adjusted progression
	In order to make a legible adjustment, I decided to make the 4th value in each column the half-way point between the darkest and the lightest. For the red scale:255-150=105 105/2=52.5 (then add 52.5 to the darkest value) For the green scale:130-000=130 130/2=65 (then add 65 to the darkest value) For the blue scale:225-75=150 150/2=75 (then add 75 to the darkest value) The remaining values were placed intuitively, and rounded to the nearest point. Made to equal approximately 1/3rd of the difference between 1 and 4 for the second and third value, and an approximate half way point between 4 and 6 for the fifth.	R150 R166 R184 R202.5 R227 R255	G000 G022 G044 G065 G097 G130	B075 B100 B125 B150 B187 B225
ColorBrew
	·         The values obtained from Color Brewer don’t seem to follow any easily definable pattern. While the blue and green levels seem to gradually increase on the spectrum, the red does not systematically increase. The amount of red in the 4th value drops below that of the second and third values, and spikes at the end to the highest level to create an almost-shite hue for the brightest value.	R152 R221 R223 R201 R212 R241	G000 G028 G101 G148 G185 G238	B067 B119 B176 B199 B218 B246

Brief discussion of your results. How do the linear and adjusted progression color ramps compare to the results from ColorBrewer? (Aprox. 150 words)

            When working on my linear progression, I selected a pre-determined purple color as my starting point. Then, in compliance with the lab instructions, I created my brightest color. I did so by estimating what the end of the range would look like, and attempted to keep the hue as close to my dark purple color as possible.  After completing the spectrum, I have used the same starting and ending point to create the adjusted progression ramp. Despite my attempt to broaden the spectrum around the dark end of the scale (as described above), the color ramps look very similar at a glance. Most of the values across the spectrum differ only by a few points, making it quite hard to distinguish without a close examination.

            The spectrum generated in Cold Brewer began with a very similar dark purple to the previous two. However, because I selected a multi hue spectrum, the degree of ‘redness’ across the spectrum does not increase regularly like in the first two color ramps. This makes for a much more legible color ramp, as the brighter colors are not only brighter, but also appearing more blue than those in the linear and adjusted ramps. The brightest value in the Cold Brewer ramp is also significantly closer to white than the brightest value in the previous ramps making the overall spectrum broader and easier to read.