A method for producing soft contact lenses, comprising the steps of: obtaining a preformed hydrogel contact lens having a non-silicone hydrogel lens body and an opaque color image printed with an ink on and/or in one of the anterior and posterior surface of the hydrogel lens body, wherein the ink comprises pigment particles, wherein the non-silicone hydrogel lens body is composed of a crosslinked product of a water-soluble, actinically-crosslinkable polyvinyl alcohol prepolymer which comprises at least 60% by mole of repeating units of vinyl alcohol (i.e.) and from 1% to 25% by mole of repeating units of formula in which: R 3 is hydrogen or a C 1 -C 6 alkyl group; R 4 is a C 1 -C 6 alkylene divalent radical; R 5 is hydrogen or C 1 -C 6 alkyl; R 6 is an ethylenically unsaturated group of or in which q1 and q2 independently of each another are zero or one, and R 7 and R 8 independently of one another are a C 2 -C 8 alkylene divalent radical, R 9 is C 2 -C 8 alkenyl; contacting the preformed hydrogel contact lens with a first aqueous coating solution of a polyanionic polymer at a pH of 4.0 or less and at a coating temperature of from 25°C to 80°C to obtain a colored contact lens precursor which is the preformed hydrogel contact lens having a layer of the polyanionic polymer thereon, wherein the polyanionic polymer is one or more homo- or copolymers of acrylic acid, methacrylic acid, ethylacrylic acid, 2-acrylamidoglycolic acid, or 2-methacrylamidoglycolic acid, wherein the layer of the polyanionic polymer encloses the preformed hydrogel contact lens having the color image; and heating the colored contact lens precursor obtained in step, in a second aqueous coating solution which comprises a water-soluble and thermally-crosslinkable hydrophilic polymeric material having azetidinium groups, at a temperature of from 60°C to 140°C for at least 30 minutes to crosslink the water-soluble thermally-crosslinkable hydrophilic polymeric material and the polyanionic polymer so as to form the colored contact lens, wherein the colored contact lens has a hydrogel coating covalently attached onto the layer of the polyanionic polymer, wherein the colored contact lens in fully hydrated state has a friction rating of 2 or lower after 7 cycles of manual rubbing as determined as described in Example 1. obtaining a preformed hydrogel contact lens having a non-silicone hydrogel lens body and an opaque color image printed with an ink on and/or in one of the anterior and posterior surface of the hydrogel lens body, wherein the ink comprises pigment particles, wherein the non-silicone hydrogel lens body is composed of a crosslinked product of a water-soluble, actinically-crosslinkable polyvinyl alcohol prepolymer which comprises at least 60% by mole of repeating units of vinyl alcohol (i.e.) and from 1% to 25% by mole of repeating units of formula in which: R 3 is hydrogen or a C 1 -C 6 alkyl group; R 4 is a C 1 -C 6 alkylene divalent radical; R 5 is hydrogen or C 1 -C 6 alkyl; R 6 is an ethylenically unsaturated group of or in which q1 and q2 independently of each another are zero or one, and R 7 and R 8 independently of one another are a C 2 -C 8 alkylene divalent radical, R 9 is C 2 -C 8 alkenyl; R 3 is hydrogen or a C 1 -C 6 alkyl group; R 4 is a C 1 -C 6 alkylene divalent radical; R 5 is hydrogen or C 1 -C 6 alkyl; R 6 is an ethylenically unsaturated group of or in which q1 and q2 independently of each another are zero or one, and R 7 and R 8 independently of one another are a C 2 -C 8 alkylene divalent radical, R 9 is C 2 -C 8 alkenyl; contacting the preformed hydrogel contact lens with a first aqueous coating solution of a polyanionic polymer at a pH of 4.0 or less and at a coating temperature of from 25°C to 80°C to obtain a colored contact lens precursor which is the preformed hydrogel contact lens having a layer of the polyanionic polymer thereon, wherein the polyanionic polymer is one or more homo- or copolymers of acrylic acid, methacrylic acid, ethylacrylic acid, 2-acrylamidoglycolic acid, or 2-methacrylamidoglycolic acid, wherein the layer of the polyanionic polymer encloses the preformed hydrogel contact lens having the color image; and heating the colored contact lens precursor obtained in step, in a second aqueous coating solution which comprises a water-soluble and thermally-crosslinkable hydrophilic polymeric material having azetidinium groups, at a temperature of from 60°C to 140°C for at least 30 minutes to crosslink the water-soluble thermally-crosslinkable hydrophilic polymeric material and the polyanionic polymer so as to form the colored contact lens, wherein the colored contact lens has a hydrogel coating covalently attached onto the layer of the polyanionic polymer,