here is your quickest method:
1. With image open, go to Select>Color Range - when Color Range opens you notice a slider for fuzziness, make sure it is set to 32 (default), the higher the number the more liberal the [sensitivity] range as you select a color (it also spreads your anti-alias feather).
2. Go out in the actual image, click the eyedropper on your color(s) you want to select, hold down the shift key - or use the + eyedropper - making sure you get the colors in the shadows and highlights of the garment. You can see in the window the areas that are being selected and be careful not to overlap into other color areas. Adjust Fuzziness if you need to expand or retreat the range.
3. Close the window and you will have a selection active (marching ants), these are the areas of color you have selected. INVERSE your selection Select>Inverse - or Control Shift i (Command Shift i on Mac). Select a color for your sepia and go to Edit>Fill... use Foreground Color, set Blending Mode to Color, 100% opacity and click OK.
There you go, deselect the marching ants and you have your isolated color.
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