




The 
clear-external-image-conversions
 function clears the external image conversions for a port. If 
gp-or-null
 is 
nil
 all conversions are cleared using the image-color-users. If 
all
 is non-
nil
 all conversions for all ports are cleared using 
gp-or-null
. Conversions are also freed if 
free-image
 is non-
nil
. By default, 
free-image
 is 
t
, 
all
 is 
(null 
gp-or-null
)
, and 
errorp
 is 
t
.