The method automatically adjusts the overall contrast and mixture of colors within a page, or specified rectangular area of a page. Because it does not adjust channels individually, Auto Contrast does not remove color casts. It maps the lightest and darkest pixels in the image to white and black which makes highlights appear lighter and shadows appear darker.
HRESULT AutoContrast([in] RECT* pRect);
- [in] Pointer to RECT structure which defines the rectangular area where the function should be applied. If this parameter is NULL, the entire page will be processed.
Returns S_OK if operation was successful or error code in other cases.