Most Creative profiles in Lightroom and Camera Raw have an Amount slider which can be used to vary the strength of the profile. (I say “most” because the creator of the profile has the option to disable the effect of the Amount slider). Note: the Raw profiles that Adobe ships do not have an Amount slider.
Using the slider is intuitive -moving the Amount slider to the left decreases the strength of the Creative profile: moving the slider to the right, amplifies the strength of the profile. But I was curious as to what was happening under the hood – so I went direct to the source and asked my teammate Max. It turns out that when working with raw files, as you decrease the Amount slider, the Creative profile is being blended with a “base” profile – within the Creative profile. The Creative profiles that Adobe ships with Lightroom and Camera Raw all use the Adobe Standard profile as their base profile, but other third parties could choose to use a different base profile (in which case, their Creative profiles would blend with their custom base profile). This means that if the Amount slider is set to zero, the result would be the same as applying the base profile.
There are a few exceptions – when working with a non-raw image such as JPEG, because there is no base profile for a JPEG, when you apply a Creative profile and decrease the Amount slider, it will blend with a generic “Color” profile. And, there is a small subset of raw and DNG files that don’t use the Adobe Standard profile as the base profile (if your image falls in this category it will show “Embedded” as the default profile). If this is the case, decreasing the Amount slider when applying a Creative profile will blend with the default, “Embedded” profile.
The SDK info for creating custom profiles can be downloaded from this link: http://www.adobe.com/go/profile-sdk