In an ink-jet recording apparatus, when an intensity of the energy of
electromagnetic waves of a predetermined region is E and an optical
density of the image recorded on a recording medium based on an image
signal is D, a controller conducts the image recording such that a
characteristic curve representing a change of the optical density D for a
logarithm of the energy intensity E becomes a monotone increasing function
or a monotone decreasing function. When .gamma..sub.1, .gamma..sub.2 and
.gamma..sub.3 are defined on the characteristic curve such that an
inclination of a line connecting points corresponding to E.sub.1 and
E.sub.2 is .gamma..sub.1, an inclination of a line connecting points
corresponding to E.sub.3 and E.sub.4 is .gamma..sub.2, and an inclination
of a line connecting points corresponding to E.sub.5 and E.sub.6 is
.gamma..sub.3, the characteristic curve is determined so as to satisfy the
following formulas:
.vertline..gamma..sub.1.vertline.<.vertline..gamma..sub.2.vertline. and
.vertline..gamma..sub.3.vertline.<.vertline..gamma..sub.2.vertline..
The image recording for the energy intensity E between E.sub.1 and E.sub.2
is conducted based on .gamma..sub.1, the image recording for the energy
intensity E between E.sub.3 and E.sub.4 is conducted based on
.gamma..sub.2, and the image recording for the energy intensity E between
E.sub.5 and E.sub.6 is conducted based on .gamma..sub.3.
