Hmm, alright, I'll figure it out.
Thanks.

What I want is quite straight forward, basically if I put it in Photoshop, I just need to adjust the HUE value in order to get different colors.

So now in codes, I wish to convert my image to HSV...

Hmm, the image looks like this
http://i165.photobucket.com/albums/u50/ylloh5633/effect_zps10812a13.png

Reason why I need to change the Hue value is because I need to maintain the glowing,...

Yea, I will know all the possible colors at compile time because each characters will have their own color and it will be preset by us.
Just that I need to change the color during runtime because...

Hmm... I don't know :(

Basically he draw a shape filled with gradient color in Photoshop, then he told me if I want to change color then I need to adjust the HUE. @@?

Actually my scenario is like this:
I was trying to do an effect in games.
Because I wanted to have different colors for different characters, so I asked my artist to give me one default color then...

I found these methods online

vec3 RGBToHSL(vec3 color)
{
vec3 hsl; // init to 0 to avoid warnings ? (and reverse if + remove first part)

float fmin = min(min(color.r, color.g), color.b); ...

Hi, I just started to learn shader and what I would like to do is changing the HUE value of an image.

Does anyone know how to do it?
I did found some articles/tutorials talk about HUE but I don't...