Before digital cameras, the only filters available for photographers were optical filters that were attached directly to the lens. While optical filters are still a common accessory for DSLR cameras today, most digital cameras also come with a variety of software filters that enable you to adjust images while the photo is being taken or afterwards while looking at the photo on the screen.
Optical filters change the light that enters the camera while the picture is being taken, which often allows for better-quality images and more control in how the image is captured. Three of the most popular optical filters include polarizing filters, UV filters and neutral density (ND) filters. Polarizing filters reduce glare caused by bright light, including reflections on water or glass. They can also enrich the shades of blue in the sky on a bright day. UV filters reduce the amount of ultraviolet light. ND filters reduce the overall light that goes through the lens, which can be useful for bright conditions when you want to use a high-aperture setting.
Image Quality Software Filters
Many software filters on cameras enable you to enhance the overall quality of a photo. A noise reduction filter, for example, can be used while the picture is being taken to reduce or eliminate bright dots that may appear in otherwise dark areas of the photo. Most other filters are applied after the picture has been taken. Enhancement filters can increase or decrease contrast, brightness or colors. Depending the camera, you can modify the red, green and blue (RGB) balance, hue saturation value (HSV) or hue saturation levels (HSL).
Touch-Up Software FIlters
Touch-up filters give you a way to modify a photo after it has been taken, while looking at the photo on the camera's LCD screen. This is done much the same way as you might edit a photo on your computer. One of the most common is the red-eye-reduction filter, which removes the redness in eyes caused by a camera flash. Depending on the camera, many of these filters allow you reduce or eliminate imperfections on the image such as the spots sometimes caused by dust on the lens.
Filter effects transform photos after the image has already been taken. Selective color filters, for example, can retain one color in the image while making all others black and white. Softeners slightly blur the details of the image, but you can often select an area, such as a person's face, to retain the focus while blurring the rest of the photo. Painting filters can alter photos to make them look like oil paintings or watercolors. Many of these filters are designed to add some fun to your photos, like turning everything into a cartoon or making a photo you took look like an antique by using a sepia-tone filter.
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