From Longman Dictionary of Contemporary Englishretouchre‧touch /ˌriːˈtʌtʃ/ verb [transitive] AVPTCPto improve a picture or photograph by painting over marks or making other small changes → airbrush postcards that have been retouched to cover the grey skies→ See Verb table
Examples from the Corpus
retouch• Nevertheless, it was the subsequent interference and attempts to retouch it that damaged Joni's work beyond repair.• All the pictures were heavily retouched so he would look younger.• You might get a slight off-set on to the blotters and you may have to retouch some areas. 