The Blur Tool is useful for smoothing features such as shadow boundaries or small artifacts or blemishes in the image. Given image (A) and its illumination field (B), for example, the blur tool can smooth the shadow boundary in the illumination field, resulting in the new illumination field (C) and product image (D).
In addition to the Size, Hardness, and Flow parameters, the Blur Tool also has a Preserve Product checkbox as shown in (E). If the box is checked, then any change made to one field is inverted and applied to the other field. For example, blurring a feature in the reflectance field would cause the inverse of that blurring to appear in the illumination field. This capability can be useful for making minor corrections to a separation, such as a minor boundary artifact at a shadow’s edge. The Product image does not change if Preserve Product is checked.
If the Preserve Product checkbox is unchecked, then any changes affect only the field being modified. Therefore, the Product image will change, as in the example below.