  The paper discusses the recovery of signals in the case that signals are
nearly sparse with respect to a tight frame $D$ by means of the $l_1$-analysis
approach. We establish several new sufficient conditions regarding the
$D$-restricted isometry property to ensure stable reconstruction of signals
that are approximately sparse with respect to $D$. It is shown that if the
measurement matrix $\Phi$ fulfils the condition $\delta_{ts}<t/(4-t)$ for
$0<t<4/3$, then signals which are approximately sparse with respect to $D$ can
be stably recovered by the $l_1$-analysis method. In the case of $D=I$, the
bound is sharp, see Cai and Zhang's work \cite{Cai and Zhang 2014}. When $t=1$,
the present bound improves the condition $\delta_s<0.307$ from Lin et al.'s
reuslt to $\delta_s<1/3$.
