reverted 4d38523bda, the long commit message

is a nice fairy tale, not more - of course the ponter deref copies the whole
params, and most other packends do it the same way: grep *params *.c, and
consult your local C "assembler frontend" bible, ...

backend/avision.c

@@ -8292,16 +8292,9 @@ sane_get_parameters (SANE_Handle handle, SANE_Parameters* params)
     }
 
   if (params) {
+    *params = s->params;
     /* add background raster lines */
-    s->params.lines += s->val[OPT_BACKGROUND].w;
+    params->lines += s->val[OPT_BACKGROUND].w;
-
-    /* copy structure members */
-    params->format = s->params.format;
-    params->last_frame = s->params.last_frame;
-    params->bytes_per_line = s->params.bytes_per_line;
-    params->pixels_per_line = s->params.pixels_per_line;
-    params->lines = s->params.lines;
-    params->depth = s->params.depth;
   }
   
   return SANE_STATUS_GOOD;