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144 lines
5.7 KiB
Python
144 lines
5.7 KiB
Python
#!/usr/bin/env python
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# -*- coding: utf-8 -*-
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# https://en.wikipedia.org/wiki/SRGB (The reverse transformation)
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def lin(c):
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return 100.0 * ((c/12.92) if (c<=0.04045) else pow((c+0.055)/1.055, 2.4))
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import sys, math
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sys.stdout.write("#include <stdint.h>\n")
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if False: # 1D illumination invariant image
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sys.stdout.write("const uint8_t invariant_table[65536] = {\n") # 65536 * 1
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for i in range(65536):
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r = ((((i >> 3) & 31) * 255) + 15.5) // 31
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g = (((((i & 7) << 3) | (i >> 13)) * 255) + 31.5) // 63
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b = ((((i >> 8) & 31) * 255) + 15.5) // 31
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# http://ai.stanford.edu/~alireza/publication/cic15.pdf
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r_lin = lin(r / 255.0) + 1.0
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g_lin = lin(g / 255.0) + 1.0
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b_lin = lin(b / 255.0) + 1.0
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r_lin_sharp = (r_lin * 0.9968) + (g_lin * 0.0228) + (b_lin * 0.0015);
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g_lin_sharp = (r_lin * -0.0071) + (g_lin * 0.9933) + (b_lin * 0.0146);
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b_lin_sharp = (r_lin * 0.0103) + (g_lin * -0.0161) + (b_lin * 0.9839);
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lin_sharp_avg = r_lin_sharp * g_lin_sharp * b_lin_sharp
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lin_sharp_avg_p = math.pow(lin_sharp_avg, 1.0/3.0) if (lin_sharp_avg > 0.0) else 0.0
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r_lin_sharp_div = 0.0
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g_lin_sharp_div = 0.0
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b_lin_sharp_div = 0.0
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if lin_sharp_avg_p > 0.0:
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lin_sharp_avg_d = 1.0 / lin_sharp_avg_p
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r_lin_sharp_div = r_lin_sharp * lin_sharp_avg_d
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g_lin_sharp_div = g_lin_sharp * lin_sharp_avg_d
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b_lin_sharp_div = b_lin_sharp * lin_sharp_avg_d
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r_lin_sharp_div_log = math.log(r_lin_sharp_div) if (r_lin_sharp_div > 0.0) else 0.0
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g_lin_sharp_div_log = math.log(g_lin_sharp_div) if (g_lin_sharp_div > 0.0) else 0.0
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b_lin_sharp_div_log = math.log(b_lin_sharp_div) if (b_lin_sharp_div > 0.0) else 0.0
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chi_x = (r_lin_sharp_div_log * 0.7071) + (g_lin_sharp_div_log * -0.7071) + (b_lin_sharp_div_log * 0.0000)
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chi_y = (r_lin_sharp_div_log * 0.4082) + (g_lin_sharp_div_log * 0.4082) + (b_lin_sharp_div_log * -0.8164)
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chi_int = max(min(int(round(math.exp((chi_x * 0.9326) + (chi_y * -0.3609)) * 127.5)), 255), 0)
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if not (i % 16):
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sys.stdout.write(" ")
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sys.stdout.write("%3d" % chi_int)
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if (i + 1) % 16:
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sys.stdout.write(", ")
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elif i != 65535:
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sys.stdout.write(",\n")
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else:
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sys.stdout.write("\n};\n")
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if True: # 2D illumination invariant image
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sys.stdout.write("const uint16_t invariant_table[65536] = {\n") # 65536 * 2
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for i in range(65536):
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r = ((((i >> 3) & 31) * 255) + 15.5) // 31
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g = (((((i & 7) << 3) | (i >> 13)) * 255) + 31.5) // 63
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b = ((((i >> 8) & 31) * 255) + 15.5) // 31
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# http://ai.stanford.edu/~alireza/publication/cic15.pdf
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r_lin = lin(r / 255.0) + 1.0
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g_lin = lin(g / 255.0) + 1.0
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b_lin = lin(b / 255.0) + 1.0
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r_lin_sharp = (r_lin * 0.9968) + (g_lin * 0.0228) + (b_lin * 0.0015);
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g_lin_sharp = (r_lin * -0.0071) + (g_lin * 0.9933) + (b_lin * 0.0146);
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b_lin_sharp = (r_lin * 0.0103) + (g_lin * -0.0161) + (b_lin * 0.9839);
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lin_sharp_avg = r_lin_sharp * g_lin_sharp * b_lin_sharp
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lin_sharp_avg_p = math.pow(lin_sharp_avg, 1.0/3.0) if (lin_sharp_avg > 0.0) else 0.0
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r_lin_sharp_div = 0.0
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g_lin_sharp_div = 0.0
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b_lin_sharp_div = 0.0
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if lin_sharp_avg_p > 0.0:
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lin_sharp_avg_d = 1.0 / lin_sharp_avg_p
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r_lin_sharp_div = r_lin_sharp * lin_sharp_avg_d
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g_lin_sharp_div = g_lin_sharp * lin_sharp_avg_d
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b_lin_sharp_div = b_lin_sharp * lin_sharp_avg_d
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r_lin_sharp_div_log = math.log(r_lin_sharp_div) if (r_lin_sharp_div > 0.0) else 0.0
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g_lin_sharp_div_log = math.log(g_lin_sharp_div) if (g_lin_sharp_div > 0.0) else 0.0
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b_lin_sharp_div_log = math.log(b_lin_sharp_div) if (b_lin_sharp_div > 0.0) else 0.0
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chi_x = (r_lin_sharp_div_log * 0.7071) + (g_lin_sharp_div_log * -0.7071) + (b_lin_sharp_div_log * 0.0000)
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chi_y = (r_lin_sharp_div_log * 0.4082) + (g_lin_sharp_div_log * 0.4082) + (b_lin_sharp_div_log * -0.8164)
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e_t_x = 0.9326
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e_t_y = -0.3609
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p_th_00 = e_t_x * e_t_x
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p_th_01 = e_t_x * e_t_y
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p_th_10 = e_t_y * e_t_x
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p_th_11 = e_t_y * e_t_y
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x_th_x = (p_th_00 * chi_x) + (p_th_01 * chi_y)
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x_th_y = (p_th_10 * chi_x) + (p_th_11 * chi_y)
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r_chi = (x_th_x * 0.7071) + (x_th_y * 0.4082)
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g_chi = (x_th_x * -0.7071) + (x_th_y * 0.4082)
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b_chi = (x_th_x * 0.0000) + (x_th_y * -0.8164)
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r_chi_invariant = math.exp(r_chi)
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g_chi_invariant = math.exp(g_chi)
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b_chi_invariant = math.exp(b_chi)
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chi_invariant_sum = r_chi_invariant + g_chi_invariant + b_chi_invariant
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r_chi_invariant_m = 0.0
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g_chi_invariant_m = 0.0
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b_chi_invariant_m = 0.0
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if chi_invariant_sum > 0.0:
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chi_invariant_sum = 1.0 / chi_invariant_sum
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r_chi_invariant_m = r_chi_invariant * chi_invariant_sum
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g_chi_invariant_m = g_chi_invariant * chi_invariant_sum
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b_chi_invariant_m = b_chi_invariant * chi_invariant_sum
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rgb565 = (int((((r_chi_invariant_m*255)*31)+127.5)/255)&0x1F)<<11 | \
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(int((((g_chi_invariant_m*255)*63)+127.5)/255)&0x3F)<<5 | \
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(int((((b_chi_invariant_m*255)*31)+127.5)/255)&0x1F)
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if not (i % 16):
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sys.stdout.write(" ")
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sys.stdout.write("0x%04X" % (((rgb565&0x00ff)<<8)|((rgb565&0xff00)>>8)))
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if (i + 1) % 16:
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sys.stdout.write(", ")
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elif i != 65535:
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sys.stdout.write(",\n")
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else:
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sys.stdout.write("\n};\n")
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