How Do I Convert RGB Values?

[harryadkins]

I use Paint Shop Pro 7.0 for repainting. How do I convert RGB values (such as 192-98-77) to the values used in Color Adjust RGB (-100 to +100)? I've been trying to develop an Excel formula to do this, but my math has nearly 40 years of rust built up. RGB values are 0-255.

Harry

[PapaXpress]

Are you talking about the ARGB values that RW uses?

[Kali]

I presume he means any RGB colour value.

Does PSP have an entry for RGB in hex values? it'd look along the lines of "#FF0ACC". Perhaps a screenshot of the colour dialog would help.

[Hawk]

Here's a color selection window from PSP 7, but I have a feeling that's not what Harry is asking about.

Image2.jpg

[harryadkins]

Here's a pic of the option I'm refering to. You select Colors / Adjust / Red/Green/Blue. The values adjust from -100% to +100% instead of 0-255 like RGB. Thanks for your help.

[Hawk]

I think you mainly have to go by what it looks like. I believe all that window does is adjust the RGB by percentages and you have to judge it by your eyes.

[harryadkins]

With three variables, R-G-B, it's very hard to "eyeball." I am hopeful for a system that might help. Unfortunately, I'm also a little color-blind, so this process has been frustrating. There must be a mathmatical relationship between 0-255 and -100-+100. However, Hawk may be right. The colors adjust differently based on the base color. Thanks for your help.

[Kali]

I presume +100% would add the whole of whatever the particular number is, to itself; so if the channel is 100, adding 50% would end up at 150. Could be totally wrong though.

[Hawk]

I believe what Harry was looking for was some correlation between the -100 and +100 and it's counterpart in the RGB values of 0 to 255, but I don't think that window in PSP 7 works like that.
All it does is increase the individual color by a percentage of where you slide the slider to, requiring eye acceptance, and being color blind might have a bit of a disadvantage there.