There has been some discussion on this issue before. Some guys provided their nicely own developed methods. Check here https://www.researchgate.net/post/How_do_I_conduct_semi_quantification_with_DAB_chromogen_IHC_in_ImageJ and https://www.researchgate.net/post/How_do_I_quantify_DAB_using_ImageJ
IHC image quantification can be made according what you want to measure by image J software( for example, nuclear area,circularity,....etc) according to following steps
1-adjustment of brightness and contrast of IHC image
2- conversion of image to 8-bit grey scale
3- Phase colour coding of the desired area .
4- Image Analysis was performed to get nuclear surface area and circularity,...etc