Definition

A photo filter is a circular piece of glass that you apply on your camera in order to enhance the image or in order to obtain certain effects (such as infrared, gradient or toning). Filters can be used to protect, as well (the UV filter). Photoshop saves time when trying to enhance images. You no longer have to buy them and painstakingly apply them so as not to break the fragile glass. All you have to do is go to Image>Adjustments>Photo Filter. The basic filters are:

• Warming Filters (85, LBA, 81)
• Cooling Filters (80, LBB, 82)
• Sepia
  

Orange Filter	Lime Filter

Pros
You can enhance the image without having to buy an actual filter. This saves money as well as time.
Also, any colour can be applied to a photo, with varying densities.
Last but not least, you do not have to worry about breaking or damaging the filters.

Cons

The filters do not cover an important aspect: that of circular polarization. As this effect is nearly impossible to obtain in Photoshop, the use of a traditional filter is highly recommended.

To sum up...
If you are an amateur photographer and want to obtain spectacular photos, you should give these filters a try. Not only do they save you a lot of money but they do not break or deteriorate like traditional filters do. However, if you are a pro and want to create outstanding vistas, then you should opt for the physical version, as Photoshop cannot replicate the polarization of light.

• Sharon Courtney's Photoshop
• Filters
  
• Infrared
• Infrared Tutorial