The Asiva Grain plug-in allows you add grain to images in a very controlled manner, which is useful when working with digital images that have a synthetic or plastic feel. This gives texture and feel to an otherwise sterile image. For example, you could add grain to the background of a portrait shot outdoors, while staying off of the flesh tones.
By specifying independent grain amounts in the color component sliders, in combination with relative levels in the three HSI curves, one can create grain patterns similar to those found in various film speeds and stocks.
The Asiva Grain filter can be applied in three different color spaces: the source image's color space (RGB or CMYK), HSI (Hue-Saturation-Intensity), or YUV (Luminance-Chrominance).
For the color space selected, sliders allow you to select the maximum grain amount for each color component in the selected color space. Note that the three curves in the three Asiva Maps then determine the relative grain amount depending upon hue, saturation and intensity curves.
Define the source colors you wish to add grain to, using the built in Hue, Saturation and Luminance (HSV) curves or maps. Sampling the colors in the area/s or an image you wish to affect with the built in Color Sampler Tool is a simple way of selecting these values. Adjusting and fine tuning the curves in the maps allows you to include or exclude certain H or S or V (Luminance values affected.
The slope of the curves will define how the filter is transitioned. A near vertical line on your Map will create sharply defined boundaries between where the filter is applied and is not, and a gently sloped curve on the Map will make the boundaries less defined.
Asiva's curves are so precise, that tedious masking prior to application of the filters are often not necessary. The Grain filter may also be applied to your Photoshop selections.