I should have used a green shirt on this one. Anyway, I'm having a problem changing the color of a red shirt without affecting my skin tone. I have reddish skin and when setting the hue/saturation of reds skin tone gets affected. ... And vice versa. If I go for my skin color afterwards and try to change it the shirt gets affected too. Any trick to get around my way around this? Please advice. Thanks.
yup, you got to isolate the one you want to chane apart from the other. use lasso magnetic, a selection tool.
There are various ways to isolate the shirt, I agree the lasso magnetic tool is great. You may also want to try masking and creating a separate layer for the shirt color alteration, this way it's easy to go back to should it need further tweaking.