Raw sharpening and noise reduction Masking
Camera Raw offers a powerful array of sharpening and noise-reduction controls within the Detail Panel (accessed by clicking the triangular panel icon on the right). Here are the key sliders explained. In most cases, holding Alt while dragging a slider will give a grayscale view to help you judge the effect.
Sharpening Amount
This slider controls the overall strength of the sharpening effect by increasing the contrast along edge details within the image. The correct amount will depend on the subject and resolution of the image. Push it until details are sharp, but beware of increasing image noise.
Radius
When we sharpen a photo we are simply increasing contrast along edges, where light pixels meet dark pixels. The Radius slider determines how far from the edge the sharpening – or ‘halos’ – will occur. A high radius is usually more suited to images with areas of low-frequency detail such as portraits, while a low radius may be better for detailed scenes like landscapes.
Detail
This lets us suppress halos and artefacts by controlling how much high-frequency detail is sharpened. A lower value is better for restricting the sharpening to strong edges, while a higher value is better for emphasising textures and surfaces in the scene. This lets us restrict the effects of the sharpening to areas of fine detail, allowing us to exclude featureless or blurred parts of the photo from becoming oversharpened. Hold Alt while dragging the slider for a black & white view. As you drag the slider across, areas will begin to appear – these will be excluded from the sharpening.
Luminance Noise
This lets us combat the grainy noise that often occurs when we shoot at high ISOs, or if we attempt to rescue an underexposed photo. Drag the slider to a point where the noise disappears, but beware of blurring fine details. Sharpening and noise reduction go hand in hand, so if we push one too far it can have an adverse effect on the other.
Color Noise
This targets blotchy spots of colour that can appear in our photos, especially in darker areas. By default it’s set to 25, which is usually enough. The Color Noise slider below this lets you set a threshold – high values protect the colour edges, while low values remove speckles of colour.