of Oph D and L1544 are also shown in MAN98 and WMA99, respectively).

The good agreement between the respective images of these cores in both types of data confirms that the features we see with ISOCAM are due to absorption by the (rather large) column density of cold dust traced at 1.3 mm, and not by fluctuations in the mid-IR background. Furthermore, the similar morphologies seen in both wavebands suggest that the mid-IR absorption images trace the same dust as the millimeter emission maps, which justifies a detailed comparison of the column density profiles derived from both tracers.

  ------------- ----------------------------------------------------------------------------------------------------------------------- ---------------------------------- ----------- --------------------- ------------------ --------------------- --------------------- --
  Name                                                                $R_{flat}$                                                                $N_{H_{2}}^{flat}$          $R_{out}$    $N_{H_{2}}^{out}$    $I_{zodi}^{MIR}$    $I_{fore}^{MIR}$      $I_{back}^{MIR}$    

                                                                         (AU)                                                                       cm$^{-2}$                 (pc)           cm$^{-2}$            (MJy/sr)            (MJy/sr)              (MJy/sr)        

                                                                          (1)                                                                          (2)                     (3)              (4)                 (5)                  (6)                   (7)          

  L1544                                                                  1900                                                            4.5 $\times 10^{22}$$^{\dagger}$     0.08       2$\times 10^{21}$          4.2          4.2$^{+0.2}_{-0.7}$   0.7$^{+0.7}_{-0.2}$  

  Oph D (LW2)                                                            3400                                                                   5$\times 10^{22}$             0.05      3.2$\times 10^{21}$         5.7          5.7$^{+1.5}_{-1.1}$   9.1$^{+1.0}_{-1.3}$  

  Oph D (LW3)                              “ & “ & “ & “ & 45 & 42.1$^{+2.6}_{-1.0}$ & 9.5$^{+2.0}_{-2.4}$\                                                                                                                                                                 
                 L1709A & 6400 & 4.5$\times 10^{22}$ & 0.18 & 3.1$\times 10^{21}$ & 10.5 & 11.3$^{+0.6}_{-1.3}$ & 1.7$^{+1.3}_{-0.6}$\                                                                                                                                      
                   L1689B s & 4000 & 4$\times 10^{22}$ &0.16 & 2$\times 10^{21}$ & 4.3 & 4.5$^{+1.2}_{-1.0}$ 