Photoshop enables you to simulate the softer grain effects found in photography. This effect works well when you need to emphasize the photographic aspects of an image while adding a uniform graphic feel. The only problem with the Photoshop Grain filter is that the grain is rendered in a spectrum of bright colorswhich is nothing like the grain found in photography. To create more natural colors, this task converts the image to Lab color and isolates the effect to the Lightness channel to maintain natural color.
Open the File and Convert to Lab Color
Choose File, Open and select the file you want to modify. Choose Image, Mode, Lab Color to convert the image into Lab color mode. In this example, we are using Lab color so that we can add a special effect to the Lightness channel without affecting the other color channels.
Select the Lightness Channel
Choose Window, Channels to open the Channels palette. Highlight the Lightness channel to select it and click the visibility icon (the eye) for the Lab composite image. This action makes only the Lightness channel visible and also previews the full composite image.
Select the Grain Filter
Choose Filter, Texture, Grain to open the Grain dialog box.
Set the Grain Type
Choose the overall grain pattern from the Grain Type drop-down list at the bottom of the dialog box. Notice the effect your selection has on the preview window at the top of the dialog box.
Set Intensity and Contrast
Adjust the Intensity slider to control the amount of grain applied to the image. Adjust the Contrast slider to make the grain pattern more or less pronounced.
Apply the Effect
Click OK to close the Grain dialog box and apply the effect. Depending on the file format you want to save the file in, you may want to convert the color mode back to RGB or CMYK.
Experimenting with Grain Type
You can select one of 10 effects from the Grain Type list in the Grain dialog box; these effects offer a wide range of styles. Take some time to experiment with the options, choosing the right effect for your image.