Standard Colors

Here are scanned about 20 percent of the paint chips from a chart of standardized colors used for rocks, but applicable to other natural materials and objects.  By way of explanation, some of the text for the Rock Color Chart is included below.

The Munsell system is the most widely accepted system of color identification in use in the United States.  This system is based on a color solid, or approximately a color sphere, which has a neutral gray central axis grading from white at the top to black at the bottom.  This property of lightness is called value.  Around the circumference or equator of the solid are the ten major hues, each of which is divided into ten numbered divisions, so that 5 marks the middle of the hue, and 10 marks the boundary between one hue and the next. Thus, any particular hue can be designated by a number and a letter such as 5R or 10YR.  Any single vertical section through the neutral gray axis and a particular hue constitutes a color chart on which the colors grade in value from light at the top to dark at the bottom, and in chroma (degree of saturation) from gray at one edge to the most vivid colors out at the margin.  Both value and chroma are numbered so any particular color can be given a numerical designation representing hue, value, and chroma such as 5R 6/4 and 10YR 8/2. ... Color names have been taken from the Inter-Society Color Council-National bureau of Standards system of names, inasmuch as the system is already widely used by organizations interested in color.... It was found by experiment that wetting the specimen merely decreases the value, that is, makes the specimen darker, but does not change the chroma.

Each chip is shown in two versions, a small "raw" image, which represents the scan as it came off the Microtek X6 scanner, and a larger image which has been "enhanced" in a way similar to most of the images on the rest of the Freshwater Molluscan Shells site, to give a result that appears pleasing on the computer screen. The scanner software has controls of its own, left on its "default" settings.

The enhancement process involved increasing the brightness, contrast, and the amount of red in the image, but varied from case to case. I used "Photoimpact", which has many of the capabilities of Adobe "Photoshop" image processing software. The actual color one perceives when comparing the color chips in the book with colors on the screen is a function of the lighting in the room, as the chips reflect from ambient light, while the computer screen fluoresces with its own. Colors seen on another monitor will be a function of the software, display, and monitor settings as well as surrounding ambient colors and lighting. The eye naturally compensates for these things to give us a view of the world in relative color. This is why color photographs taken under incandescent light appear brownish, while those taken in the shade under open sky will appear bluish without special filters and appropriate film. When compared to colors from the Munsell software, the raw scanned images were often truer than the "enhanced," so one might consider the latter to represent objects as having been brought out from the scanner's cold fluorescent reality into warm incandescent light.

Typical RGB color values are included for the scanned images. They vary in a small range over the image of each chip. Also included are cells with the background set to that color taken from Munsell software, along with the decimal numeric values it gives. Please visit http://www.Munsell.com/ for the software gratis.

 

Red hues
Color Name
Munsell designation
Munsell color values, bkg.		   scanned
color
chips		   Typical pixels
from scans,
raw and enhanced
Grayish orange pink
10 R 8/2
215, 196, 190		  
  235, 221, 221
255, 255, 255
Pale red
5 R 6/2
163 143 141		  
  158 139 133
205 164 160
Moderate reddish brown
10 R 4/6
141, 81, 65		  
  148, 86, 61
200, 108, 87
Blackish red
5 R 2/2
67, 47, 49		  
  69, 61, 59
105, 75, 73


Orange hues
Color name
Munsell designation
Munsell color values, bkg		   scanned
color
chips		   Typical pixels
from scans
Very pale orange
10 YR 8/2
214, 198, 175		  
  221, 221, 197
255, 255, 245
Moderate orange pink
5 YR 8/4
233, 193, 162		  
  240, 201, 158
255, 250, 200
Dark yellowish brown
10 YR 4/2
110, 94, 76		  
  110, 102, 76
158, 125, 92
Dusky brown
5 YR 2/2
65, 49, 41		  
  68, 60, 58
104, 73, 70


Yellow hues
Color name
Munsell designation
Munsell color values, bkg		   scanned
color
chips		   Typical pixels,
from scans
Grayish yellow
5 Y 8/4
214, 201, 145		  
  209 209 157
255 255 143
Mod. greenish yellow
10 Y 7/4
178,176, 120		  
  172 182 111
231 225 137
Grayish olive
10 Y 4/2
99, 98, 75 		 
  99 110 76
143 138 98
Olive gray
5 Y 3/2
80, 73, 55 		  |
   74 81 65
112 100 78


Greens and yellow greens
Color name,
Munsell designation
Munsell color values, bkg.		   scanned
color
chips		   Typical pixel
from scans
Very pale green
10 G 8/2
177 207 196 		 
  175 209 208
239, 255, 255
Moderate yellowish green
10 GY 6/4
122 156 118		  
  118 167 122
174 208 158
Dusky yellow green
5 GY 5/2
117 124 102		  
  106 118 94
150 145 115
Dusky green
5 G 3/2
61 77 69 		 
  64 90 81
95 105 81


Blue, green, and purple hues
color name
Munsell designation
Munsell color values, bkg		   scanned
color
chips		   Typical pixels
from scans
Light blue green
5 BG 6/6
70 162 154		  
  96 162 176
135 203 216
Dusky blue green
5 BG 3/2
57 77 76 		 
  58 78 87
90 97 105
Pale pink
5 RP 8/2
211 197 201 		 
  213 202 208
255 252 253
Grayish purple
5 P 4/2
103 93 109 		 
  97 94 105
144 115 133
Very dusky red purple
5 RP 2/2
88 68 76 		 
  75 67 78
112 84 98


Low chroma grays. I have included colors off
the rock color chart for comparison.

color name
Munsell designation
Munsell color values, bkg.		   scanned
color
chips		   Typical pixels
from scans
True white (HTML)
-
255 255 255		   none   -
Munsell true white
N 9.5
243 243 243		   none   -
         
White
N 9
228 228 228		  
  211 222 218
255 255 253
Medium gray
N 5
122 122 121		  
  114 121 127
145 135 136
Black
N 1
34 34 34		  
  44 49 45
52 45 39
Munsell true black
N 0.5
4 3 3 		  none   -
True Black (HTML)
-
0 0 0 		  none   -
Dark greenish gray
5 GY 4/1
95 98 88		  
  78 92 77
98 97 79

 

scanned color chips from:

ROCK-COLOR CHART

[no copyright]

Prepared by
THE ROCK-COLOR CHART COMMITTEE
.....
1948
Distributed by
THE GEOLOGICAL SOCIETY OF AMERICA, BOULDER, COLORADO
Reprinted 1951, 1963, 1970, 1975, 1979

The arrangement of chips in a later 1991 version is copyrighted. New ones are available at
http://granite.geosociety.org/bookstore/
http://www.geosociety.org/

Scanner Distortion

The scanning of three-dimensional objects introduces a distortion not discussed elsewhere. These images were made with the same scanner, as above. They were not rotated. The light and sensing element is oriented horizontally, and moves from top to bottom.  Flat bed scanners have a substantial depth of focus, but suffer from a peculiar lateral compression at a distance greater than a few cm. This is caused by the optics and geometry of the CCD sensing array, where elements sample light radially outward from a more central location, so that a more distant object intersects fewer of their lines of sight. Both blurring and distortion become substantial at 5 cm when 50 pixels/inch resolution is used, and unacceptable much beyond that. Fortunately, most specimens are not large, and those that are can be photographed with a digital or film camera. 

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Small transparent plastic cups,
marks on lower one are cm.		   Scanned view from base of cups.
Both ends are round!

 


Scanned view looking into cups. Diameter is 7.3 cm, 2.95 in.

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