The technic used here can be used to change the color of anything you want in a picture. In this tutorial, I am going to change the color of a flower. First of all you have to install Adobe Photoshop CS (any version, but preferably version 9 or higher.
1. Open a flower image or what ever the image you want to change.
2. Clicks the 'Quick Mask Mode' button located in the left down corner (or you can just press 'Q').
3. Select 'Brush Tool' or press B then select a color in the color button situated in the left down corner for the brush. In this tutorial I select the red color.
4. Now we are going to draw the flower, don't worry if you exceed the bounds, we will fix it later.
5. Then clicks on the Standard Mode button located previous to the Quick Mask Mode button. You will have something picture below.
6. Go to 'Layer -> New Layer' in the main menu and the click on it or press (Ctrl + Shift + N). The result of this action is separating the mask from the original picture that we created in steps above.
7. Select a color in the same button of the step 3 and the click on the Paint Bucked Tool button or press G. In this tutorial we select the red color.
8. Clicks over the flower to apply the selected color. The result is something like the picture below.
9. Select 'Window -> Layer' in the main menu if you dont' have the 'Layer' window visible. Then right click on the current selected layer and select Blending Options menu item.
10. In the 'Layer Style' window (Right Click -> 'Blending Options'), set the 'Blend Mode' to 'Soft Light' option and clicks OK to see the result.
11. Now fix the exceeding bounds problem with the 'Erase Tool', you can select it click on the button located in left middle side of the Photoshop envoironment or pressing E.
12. The image below show the result of the erase tool.
As a result of all the steps the blue color of the flower turns into violet, if you want to emphatize the color just duplicate the mask layer that you create in step 9.