When the area you want to select is predominantly one color, try using the color range as a selection criterion. This approach selects all the pixels in an image based on a specified color value. The color-range controls let you designate the exact range so that you can fine-tune the selection to a specific set of colors.
Open the File
Choose File, Open to launch the desired file.
Select the Color Range Command
Choose Select, Color Range to launch the Color Range dialog box.
Configure the Dialog Box
Click the arrow to the right of the Select field to access the menu and drag to select Sampled Colors. Start with the Fuzziness slider set to 40, choose the Selection radio button, and set the Selection Preview option to None.
Sample a Color
Move the cursor onto the image; notice that the cursor changes to an eyedropper as it moves over the image. Then click on a color you want to select. In this example, I clicked to select the purple in the flower; the preview in the dialog box shows how much of the image has that color. You can control how much variation of that color is selected by adjusting the Fuzziness slider.
Adjust the Fuzziness Slider
Increase or decrease the Fuzziness slider to include more or less of the color in the selection. Choose the Black Matte and White Matte options in the Selection Preview list in the Color Range dialog box to evaluate the selection area.
Add Additional Colors
Select the Plus Eyedropper from the dialog box and click on the image to add additional colors to the selected range. Click OK to close the dialog box and make the selection. If the selection is not to your satisfaction, adjust the Fuzziness slider and try again.
To check the selection in more detail, select Grayscale, Black Matte, White Matte, or Quick Mask from the Selection Preview drop-down list to show the selection results in the main image window. Grayscale shows selected areas in white and unselected areas in black. Black Matte shows selected areas as normal and unselected areas as flat black. White Matte shows selected areas as normal and unselected areas as white. Quick Mask places a mask over the selected or unselected areas, depending on how the Quick Mask Options are set (see the following task for details). To select all of a particular color or tonal range in an image, choose the desired color from the Select drop-down list. You also can select Out of Gamut to show which colors would be lost in an RGB-to-CMYK file conversion.