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I am trying to get a hex value out of material color. I find an reply here by @douripo: Get Hex triplet for color and real 256 RGB from diffuse Color using python

it successfully converts most of the colors to hex correctly. except a few. here is an example it does not convert right.

in blender, add a material to default cube and manually set its diffuse_color to hex 60590A (brown-ish yellow)

run below code in text editor, it would return 6059AA (purple-ish blue). could anyone check where went wrong? and hopefully a fix?

import bpy import math #code by : brecht - devtalk.blender.org def to_hex(c): if c < 0.0031308: srgb = 0.0 if c < 0.0 else c * 12.92 else: srgb = 1.055 * math.pow(c, 1.0 / 2.4) - 0.055 return hex(max(min(int(srgb * 255 + 0.5), 255), 0)) def toHex(r,g,b): rgb = [r,g,b] result = "" i=0 while i < 3: val = str(to_hex(rgb[i])) val = val[2:] if len(val) == 1: val += val result+=val i+=1 return result ob = bpy.context.object color_inferior = ob.active_material.diffuse_color a = toHex(color_inferior[0],color_inferior[1],color_inferior[2]) print (a)
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  • $\begingroup$ 1% is a gross exaggeration: with just integers for colors it would be 16 / 256 cubed or less than one ten thousands of one percent of all possible colors.... , lol. Good spot. IIRC there is another answer re this converting both ways. ... actually prob less, 15 numerator since zero 00 would have worked as expected too. $\endgroup$ Commented Aug 15, 2021 at 7:54
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    $\begingroup$ That's counting colors where every RGB value is wrong, It's more like 17% where at least one RGB value is wrong. $\endgroup$ Commented Aug 15, 2021 at 8:09
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    $\begingroup$ @scurest No doubt it's OR ie 3 * 15 / 256 .. not AND never was good at stats $\endgroup$ Commented Aug 15, 2021 at 8:47

1 Answer 1

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The issue occurs when str(to_hex(rgb[i]))[2:] returns a length 1 value, which is the case for blue in example given "0xa".

 if len(val) == 1: val += val

incorrectly turning it into "aa" instead of "0a". Using val = "0" + val will correct the issue. Another option, used below, is string formatting to convert an integer i into a zero padded length 2 hex string "%02x" % i

Here's a cleaned up version:

def linear_to_srgb8(c): if c < 0.0031308: srgb = 0.0 if c < 0.0 else c * 12.92 else: srgb = 1.055 * math.pow(c, 1.0 / 2.4) - 0.055 if srgb > 1: srgb = 1 return round(255*srgb) def toHex(r, g, b): return "%02x%02x%02x" % ( linear_to_srgb8(r), linear_to_srgb8(g), linear_to_srgb8(b), )
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  • $\begingroup$ Fantastic !!! it works like a charm. thank you so very much for pointing it out and fixing it. $\endgroup$ Commented Aug 15, 2021 at 18:40

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