Use of specific heterocyclic couplers, which are derivatives of 7-amino-1,2,3,4-tetrahydroquinoline of formula (I) and also their salts with an organic or inorganic acid or base, their optical or geometric isomers and / or their solvates, such as hydrates: ** Formula ** formula (I) in which: - R1, R2, R3, R4, R5 and R6, which may be identical or different, represent a hydrogen or halogen atom； a linear or branched C1-C6 alkyl radical optionally substituted with one or more hydroxyl groups, preferably with a single hydroxyl group； a carboxyl radical； a (C1-C6) alkoxy-C (O) -O-R radical, R representing a linear or branched C1-C6 alkyl radical； an alkylcarbonyloxy -OC (O) -R radical, where R is as previously defined； preferably, R1, R2, R3, R4, R5 and R6, which may be identical or different, represent a hydrogen atom, or a C1-C4 alkyl radical； - Ra, Rb and Rc, which may be identical or different, represent a hydrogen or halogen atom, or a C1-C6 alkyl radical； preferably, Ra, Rb and Rc are identical and represent a hydrogen atom； - X represents i) an amino radical -NT1T2, ii) an aminoalkylamino radical -N (T3) -L-NT1T2, or iii) an oxyalkylamino radical -O-L-NT1T2； - T1 and T2, which may be identical or different, represent a linear or branched C1-C6 alkyl radical optionally substituted with one or more hydroxyl radicals, preferably with a single hydroxyl group； - or also, T1 and T2 together, with the nitrogen atom to which they are attached, form a saturated or unsaturated heterocycle comprising 5 to 7 members, one of whose members may be a heteroatom chosen from O, S and N； it being possible that said heterocycle is optionally substituted with one or more linear or branched C1-C4 alkyl radicals or linear or branched C1-C4 hydroxyalkyl； - T3 represents a hydrogen atom or a linear or branched C1-C6 alkyl radical optionally substituted with one or more hydroxyl radicals, preferably with a single hydroxyl group； - L represents a linear or branched C1-C10 alkylene hydrocarb
