Photoshop - Layer Mask

----- Layer Mask ------
1. Ctrl J to insert new layer
2. Add layer mask
3. Click on Layer 1 thumbnail then : Image->Adjustment->black&white->click OK
4. Click on layer mask thumbnail -> Set foreground color to black
5. Paint the object that you want to have color
Mode: Normal
Opacity: 100% (more color)
Hardness : 20%
6. When the paint is done, click the Layer 1 thumbnail.
7. Click filter ->noise->median
8. Set Radius : 3-5 pixel to blur the background
9. Click OK.

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Photoshop - Eye Color Change

----- Eye Colour Change ------
1.Drag a picture into PS.
2.Zoom in the picture (eye)
3.Click the elliptical Marquee Tool.
4.Draw a same area on the eye (press shift + , press Alt -)
5.Image->Adjustment->Hue/Saturation (Play around it to get colour you want)
6.File-> New->Give a name
7.File->Place->Choose the photo you want (repeat to choose more photo)
8.Click->Horizontal Type Tool
9.Enter text you want
10.Done

Photoshop - Hair Color Change

----- Hair Colour Change -----
1.Drag a picture into PS.
2.Click the icon "Edit in Quick Mask Mode'.
3.Click the Brush Tool then highlight all the hair.
4.Click Magic Wand Tool.Make sure the perimeter is covered the whole hair (set tolerance=30, shift+click=add to selection, Alt+click=subtract from selection)
5.Click layer->New Layer->Solid Color
6.Give a name,Reduce some Opacity, Mode change to Soft light or other setting.
7.Done