Initial Commit

batchColorDE.py

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+'''
+   batchColorDE.py
+   Batch calculates CIE76 DeltaE values from RGB values in csv files. I plan to add a
+   CIE2000 DeltaE implementation in the future.
+   by Nayan Sawyer
+   started Jan 19 2022
+   version 1.0.0 Jan 22 2022
+
+      This is an implementation of the math on http://brucelindbloom.com for comparing
+      a large number of RGB pairs using the CIE76 standard. All credit for the math goes to 
+      Bruce Lindbbloom and the Commission Internationale de l'Eclairage which defines the 
+      standards.
+
+      This program is fairly straight forward to use, however it does not sanitize the csv 
+      that you point it towards, so it is important to double check your files before use.
+      The csv format to use is three integer RGB values seperated with commas, and a return 
+      character at the end of the line. This is the format output by google sheets when you 
+      export to csv. Like so
+
+         162,101,45
+         197,136,109
+         221,221,217
+         185,115,8
+         187,145,20
+
+      The first RGB group on line 1 of the csv of the sample data set will be compared to 
+      the first RGB group on line 1 of the csv of the reference data set.
+
+      {0} - There is only one page 
+      {1} In the RGBtoLab() function, the variable names in the XYZ to Lab section match the 
+      variable names used on http://brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
+      to make the code implementation more legible. 
+'''
+import numpy as np
+
+def RGBtoLab(colorArray):
+   # To convert RGB to XYZ a conversion matrix is required.
+   # This one is for sRGB and is based on the D65 reference white.
+   # For more information see above {0}
+   RGBtoXYZ_D65_matrix = np.array([[0.4124564,0.3575761,0.1804375],
+                                   [0.2126729,0.7151522,0.0721750],
+                                   [0.0193339,0.1191920,0.9503041]])
+
+   '''
+      Scale RGB to pref for matrix multiplication
+   '''
+   # Scale RGB values between 0 and 1
+   colorArray = colorArray / 255
+
+   # Inverse sRGB companding
+   colorArray = np.where((colorArray <= 0.04045) & (colorArray > 0.04045), colorArray / 12.92, ((colorArray + 0.055)/1.055) ** 2.4) 
+
+
+   '''
+      Matrix multiplication to produce XYZ format
+   '''
+   # Requires transposition because the color triads are row wise, not column wise in the csv format. 
+   # This turns the tall, 3 wide matrix into a wide, 3 tall matrix so that the multiplication can take place,
+   # then transposes it back for the later steps.
+   colorArray = np.transpose(np.matmul(RGBtoXYZ_D65_matrix, np.transpose(colorArray)))
+   #print("XYZ\n" + str(colorArray))
+
+
+   '''
+      Convert XYZ to Lab using D65 reference white {1}
+   '''
+   # Ref white in XYZ (D65)
+   Xr = 0.950470
+   Yr = 1.0
+   Zr = 1.088830
+
+   e = 0.008856
+   k = 903.3
+
+   # Get xr yr zr
+   for i in range(len(colorArray)):
+      colorArray[i][0] = colorArray[i][0] / Xr
+      colorArray[i][1] = colorArray[i][1] / Yr
+      colorArray[i][2] = colorArray[i][2] / Zr
+
+   # get fx fy fz
+   colorArray = np.where((colorArray > e), colorArray ** (1/3), (k * colorArray + 16) / 116)
+
+   # get Lab
+   for i in range(len(colorArray)):
+      fx = colorArray[i][0]
+      fy = colorArray[i][1]
+      fz = colorArray[i][2]
+      colorArray[i][0] = (116 * fy) - 16
+      colorArray[i][1] = 500 * (fx - fy)
+      colorArray[i][2] = 200 * (fy - fz)
+
+   #print("\nLab\n" + str(colorArray))
+
+   return(colorArray)
+
+def CIE76DeltaE(sample, reference):
+   out = []
+   for i in range(len(sample)):
+      out.append(((sample[i][0] - reference[i][0]) ** 2 + (sample[i][1] - reference[i][1]) ** 2 + (sample[i][2] - reference[i][2]) ** 2) ** (1/2))
+   return out
+
+
+'''
+PROGRAM START
+'''
+verbose = True # Print extra information
+
+# Digest csv
+sample = np.genfromtxt(".\\demo_sample.csv",delimiter=',')
+key = np.genfromtxt(".\\demo_key.csv",delimiter=',')
+
+if verbose: print("sample\n" + str(sample))
+if verbose: print("key\n" + str(key))
+
+# Covert to Lab color space
+sample = RGBtoLab(sample)
+key = RGBtoLab(key)
+
+if verbose: print("\nLab sample\n" + str(sample))
+if verbose: print("Lab key\n" + str(key))
+
+# Output the DeltaE for each pair
+print("\nDeltaE")
+for i in CIE76DeltaE(key,sample):
+   print(i)

demo_key.csv

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+165,124,126
+175,147,176
+184,176,193
+173,154,144
+172,165,152
+171,139,144
+181,168,198
+148,139,183
+181,174,191
+187,178,195
+194,185,204
+189,182,196
+174,161,177
+158,103,69
+124,80,24
+40,66,106

demo_sample.csv

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+162,101,45
+197,136,109
+221,221,217
+185,115,8
+187,145,20
+171,111,46
+215,155,170
+144,94,140
+202,186,171
+209,203,200
+210,202,199
+107,198,199
+209,199,202
+151,59,26
+153,103,5
+22,48,40

matrix.csv

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+0.4124564,0.3575761,0.1804375
+0.2126729,0.7151522,0.0721750
+0.0193339,0.1191920,0.9503041

readme.md

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+# Batch Color DeltaE CIE76
+## CIE2000 support planned for future
+
+This is an implementation of the math on http://brucelindbloom.com for comparing
+      a large number of RGB pairs using the CIE76 standard. All credit for the math goes to
+      Bruce Lindbbloom and the Commission Internationale de l'Eclairage which defines the
+      standards.
+
+This program is fairly straight forward to use, however it does not sanitize the csv
+      that you point it towards, so it is important to double check your files before use.
+      The csv format to use is three integer RGB values seperated with commas, and a return
+      character at the end of the line. This is the format output by google sheets when you
+      export to csv. Like so
+
+         162,101,45
+         197,136,109
+         221,221,217
+         185,115,8
+         187,145,20
+
+The first RGB group on line 1 of the csv of the sample data set will be compared to
+      the first RGB group on line 1 of the csv of the reference data set.
+
+      {0} - There is only one page
+      {} In the RGBtoLab() function, the variable names in the XYZ to Lab section match the
+      variable names used on http://brucelindbloom.com/index.html?Eqn_RGB_XYZ_Matrix.html
+      to make the code implementation more legible.