These chemicals, which should be added to the developer in quantities from 0.1–0.2 grams per litre, impart to the developer valuable additional properties. They have strong anti-fogging properties.

With development papers, developer improvers produce purer and deeper image tones. Developer improvers help to maintain the tone and brilliance of a print, which has received longer or shorter development time, owing to incorrectly estimated exposure. Thus the latitude of the paper is increased, and waste is reduced.

There is a number of developer improvers on the market, and choice should be made according to the type of material (film, printing or enlarging paper) and the required image tone.