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September 29, 2017 10:47
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PL/Pgsql function to convert color in HSL to RGB hex code
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| CREATE OR REPLACE FUNCTION hsl2rvb_hexa(hue float, sat float, light float) | |
| RETURNS text AS $$ | |
| declare | |
| c float := sat*light; | |
| tp float := (hue/60.0); | |
| x float := c*((1-abs((tp::int)%2-1))::float); | |
| m float := light-c; | |
| rp float; | |
| vp float; | |
| bp float; | |
| r int; | |
| v int; | |
| b int; | |
| BEGIN | |
| case | |
| when (tp>=0 and tp<1) then | |
| rp=c; | |
| vp=x; | |
| bp=0.; | |
| when (tp>=1 and tp<2) then | |
| rp=x; | |
| vp=c; | |
| bp=0.; | |
| when (tp>=2 and tp<3) then | |
| rp=0.; | |
| vp=c; | |
| bp=x; | |
| when (tp>=3 and tp<4) then | |
| rp=0.; | |
| vp=x; | |
| bp=c; | |
| when (tp>=4 and tp<5) then | |
| rp=x; | |
| vp=0.; | |
| bp=c; | |
| when (tp>=5 and tp<6) then | |
| rp=c; | |
| vp=0.; | |
| bp=x; | |
| else | |
| rp=0.; | |
| vp=0.; | |
| bp=0.; | |
| end case; | |
| r=((rp+m)*255)::int; | |
| v=((vp+m)*255)::int; | |
| b=((bp+m)*255)::int; | |
| return format('#%02s%02s%02s',to_hex(r),to_hex(v),to_hex(b)); | |
| END; | |
| $$ LANGUAGE plpgsql; |
BTW my Postgres version is 12.12. Is this too new?
Author
Hi, I don't use this since a lot of time!
But I think think that:
- hue must be in [0;360]
- sat must be in [0;1]
- light must be in [0;1]
Hi Thibault,
Thanks for your reply. I can imagine that something you made 5 years ago is still at the top of your brain.
Hue should be indeed 0-360 degrees. Saturation and lightness should be 1-100 percent. Is that what you mean with [0;1]?
I’m looking for a way to select colors that are recognizable for the colorblind, like for instance secondary colors. The HSL colorspace is good to choose from but you’ll need the HEX representation to get it to work in an application.
Kind regards,
Michiel
… Op 4 nov. 2022, om 08:37 heeft Thibault Coupin ***@***.***> het volgende geschreven:
@tcoupin commented on this gist.
Hi, I don't use this since a lot of time!
But I think think that:
hue must be in [0;360]
sat must be in [0;1]
light must be in [0;1]
=> https://en.wikipedia.org/wiki/HSL_and_HSV#To_RGB <https://en.wikipedia.org/wiki/HSL_and_HSV#To_RGB>
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Author
yes 25% = 0.25
but take care of conversion between int and float. You need to cast your int to float and then divided it by 100.0
Hi Thibault,
Great, thanks. Select hsl2rvb_hexa(0,(0.93),(0.93)) gives the expected conversion #ed1111 (with or without a cast to float).
The only thing that puzzles me is that above 93% (0.94 - 1.0) I get one digit hex output with spaces, like #f0 e e
Sorry to be a pain i.t.a but I hope you can help me.
Kind regards,
Michiel
… Op 4 nov. 2022, om 09:44 heeft Thibault Coupin ***@***.***> het volgende geschreven:
@tcoupin commented on this gist.
yes 25% = 0.25
but take care of conversion between int and float. You need to cast your int to float and then divided it by 100.0
—
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Hi Thibault,
I added LPAD() to the last line of your script which solved for me the missing zero’s. The function is working fine now.
Thanks.
Kind regards,
Michiel
return format('#%02s%02s%02s',LPAD(to_hex(r),2,'0'),LPAD(to_hex(v),2,'0'),LPAD(to_hex(b),2,'0'));
… Op 4 nov. 2022, om 09:44 heeft Thibault Coupin ***@***.***> het volgende geschreven:
@tcoupin commented on this gist.
yes 25% = 0.25
but take care of conversion between int and float. You need to cast your int to float and then divided it by 100.0
—
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tp must not be converted to int before doing modulo. Instead use this modulo function https://stackoverflow.com/a/53487651/289827
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Thanks for sharing this. However, I'm a bit confused. HSL 0,100,100 (red) should be ff0000 in hex color space. Your function gives me #639cffd97aacffd97aac. What am I doing wrong?
Kind regards,
Michiel