RGB to HEX

[jwarrent]

Hey guys, I'm hoping someone out there can help me find a good way to convert an RGB value to HEX. I've searched the forums and can't seem to find anything that fits this task quite right.

[Corey]

Here's a good design time converter:

http://www.321webmaster.com/colorconverter.php

Here's a good explanation if you want to make a function to do this at runtime:

http://www.katsueydesignworks.com/wmp_rgb_hex.htm

Corey Milner
Creative Director, Indigo Rose Software

[Worm]

When you say RGB, I'm assuming you have each color in the decimal equivalant of 0-255. Send each color (Red, Green, and Blue) to this function

if your RGB is 255, 0, 255 then you could do something like this:

Hex = "#" .. DEC2HEX(255) .. DEC2HEX(0) .. DEC2HEX(255)

--[[Global Functions]]--
function DEC2HEX(nRGB)
	--This only works for number 255 or less
	nRGB = String.ToNumber(nRGB)
	nBase= Math.Floor(nRGB / 16)
	nPlus= Math.Mod(nRGB, 16)
	return GetHexValue(nRGB)..GetHexValue(nPlus)
end
	
function GetHexValue(nNum)
	nNum=String.ToNumber(nNum)
	if nNum == 10 then
		nNum="A"
	elseif nBase == 11 then
		nNum = "B"
	elseif nBase == 12 then
		nNum = "C"
	elseif nBase == 13 then
		nNum = "D"
	elseif nBase == 14 then
		nNum = "E"
	elseif nBase == 15 then
		nNum = "F"
	end		
	return nNum
end

Sample Call:

Dialog.Message("Color", "The HEX value of decimal 255 is:  " .. DEC2HEX(255))

[TJ_Tigger]

There is also a predefined LUA function called tonumber. Here are the details from the LUA reference guide.

tonumber (e [, base])
Receives one argument, and tries to convert it to a number. If the argument is already a number or a string convertible to a number, then tonumber returns that number; otherwise, it returns nil.
An optional argument specifies the base to interpret the numeral. The base may be any integer between 2 and 36 inclusive. In bases above 10, the letter `A' (either upper or lower case) represents 10, `B' represents 11, and so forth, with `Z' representing 35.

In base 10 (the default), the number may have a decimal part, as well as an optional exponent part (see Section 4.3). In other bases, only integers are accepted.

decimalval = tonumber(FF, 10)

hexvalue = tonumber(255, 16)

[Stefan_M]

Solution with tables.


Stefan_M

[Worm]

I tried that Tig, and the results were not what I expected.

hexvalue = tonumber(255, 16)

give me a value of 597

[Corey]

Groovy functions Wormcat.

Corey Milner
Creative Director, Indigo Rose Software

[JimS]

There are only 10 types of people in the world:
Those who understand binary, and those who don't!

That's funny!

Worm, thanks for the function.

Tigger, I saw that tonumber function also, but I can't seem to get it to work 'correctly' or at least the way I expect it to. Have you?
I get errors with:

decimalval = tonumber(FF, 10);

I'm not sure what I'm doing wrong.


Edit: Sorry, I didn't mean to repost the same question as Worm did

[jwarrent]

Thanks a bunch guys! Worm, those two functions work great, but there are a couple of misplaced variables.. Here's the changed code:

function DEC2HEX(nRGB)
	--This only works for number 255 or less
	nRGB = String.ToNumber(nRGB)
	nBase= Math.Floor(nRGB / 16)
	nPlus= Math.Mod(nRGB, 16)
	return GetHexValue(nBase)..GetHexValue(nPlus)
end
	
function GetHexValue(nNum)
	nNum=String.ToNumber(nNum)
	if nNum == 10 then
		nNum="A"
	elseif nNum == 11 then
		nNum = "B"
	elseif nNum == 12 then
		nNum = "C"
	elseif nNum == 13 then
		nNum = "D"
	elseif nNum == 14 then
		nNum = "E"
	elseif nNum == 15 then
		nNum = "F"
	end
	return nNum
end

[TJ_Tigger]

sorry should have tested before I post

decnum = tonumber("ff",16);
Dialog.Message("decnum",decnum);

[Worm]

Thanks for catching my mistakes jwarrent.

But it looks like the better way to go is how Tig has shown using the tonumber function in LUA. Check out his last post.

You go Tig'man!

[JimS]

Good job Tigger! That fixed it. I’m sure glad one of us is smart enough to get it to work. Nope, I didn’t even think of quotation marks. Thanks, this looks like it’s probably the easiest solution for most things.

Stefan, that’s a nice example. Lately I’ve found myself downloading other of your examples too. Good job, thanks a lot. It’s great that the Forums has yet another great contributor.

[TJ_Tigger]

Here is how you can do it the other way too.

hexnum = string.format("%X", 255);
Dialog.Message("hexnum",hexnum);

or for lowercase

hexnum = string.format("%x", 255);
Dialog.Message("hexnum",hexnum);

[Corey]

That is groovy Tiggcat. I had tried, and failed, to figure that out at one point myself.

Corey Milner
Creative Director, Indigo Rose Software