int im_makerw( image )
DESCRIPTIONim_makerw(3) attempts to make image writeable, ready for an in-place operation. Its actions are just as those for im_incheck(3), except that descriptors which after im_incheck(3) end up as IM_MMAPIN descriptors, magically become IM_MMAPINRW descriptors.
Extreme caution is urged! You can permanently damage valuable data with this call.
RETURN VALUEThe function returns 0 on success and -1 on error.
National Gallery, 1992