A method for obtaining a procedure which an operator is to follow for dyeing hair, comprising steps of: predisposing an electronic database which, as a function of a colour code attributable to a portion of hair, of a value indicating a relative quantity of white hairs present in the portion of hair and of the colour that is to be applied to the hair, supplies the procedure that an operator is to follow for dyeing hair; acquiring an image of at least a portion of hair using an image acquiring device; processing data of the acquired image as follows: obtaining the colour code associable to the portion of hair; analysing the pixels of the portion, with a determination of the relative parameters at least in relation to the colour of the pixels; evaluating the average colour of the entirety of the pixels with exclusion of the pixels falling within the range of the white hairs; comparing the value of the average colour with a plurality of colour values relative to a plurality of "sample locks" of hair identifying the colour code that coincides with the value of the colour of a "sample lock" from among the "sample locks" which least deviates from the average colour value; obtaining a value indicating a relative quantity of white hairs present in the portion of hair; acquiring information indicating the colour that is to be applied to the hair for obtaining colour that the user desires for her or his hair; obtaining, from the database, the procedure that an operator is to follow for dyeing hair, as a function of: the colour code of the portion of hair; the value indicating a relative quantity of white hairs present in the portion of hair obtained from the processing of the acquired image; and of the colour that is to be applied to the hair, obtained from the acquired information. predisposing an electronic database which, as a function of a colour code attributable to a portion of hair, of a value indicating a relative quantity of white hairs present in the portion of hair and of the colour that is to be applied to the hair, supplies the procedure that an operator is to follow for dyeing hair; acquiring an image of at least a portion of hair using an image acquiring device; processing data of the acquired image as follows: obtaining the colour code associable to the portion of hair; analysing the pixels of the portion, with a determination of the relative parameters at least in relation to the colour of the pixels; evaluating the average colour of the entirety of the pixels with exclusion of the pixels falling within the range of the white hairs; comparing the value of the average colour with a plurality of colour values relative to a plurality of "sample locks" of hair identifying the colour code that coincides with the value of the colour of a "sample lock" from among the "sample locks" which least deviates from the average colour value; obtaining a value indicating a relative quantity of white hairs present in the portion of hair; acquiring information indicating the colour that is to be applied to the hair for obtaining colour that the user desires for her or his hair; obtaining, from the database, the procedure that an operator is to follow for dyeing hair, as a function of: the colour code of the portion of hair; the value indicating a relative quantity of white hairs present in the portion of hair obtained from the processing of the acquired image; and of the colour that is to be applied to the hair, obtained from the acquired information.