--- ray/doc/man/man1/rcontrib.1	2020/09/09 21:28:19	1.18
+++ ray/doc/man/man1/rcontrib.1	2022/10/19 18:23:14	1.20
@@ -1,4 +1,4 @@
-.\" RCSid "$Id: rcontrib.1,v 1.18 2020/09/09 21:28:19 greg Exp $"
+.\" RCSid "$Id: rcontrib.1,v 1.20 2022/10/19 18:23:14 greg Exp $"
 .TH RCONTRIB 1 5/25/05 RADIANCE
 .SH NAME
 rcontrib - compute contribution coefficients in a RADIANCE scene
@@ -121,10 +121,25 @@ Note that output flushing via zero-direction rays is d
 .I \-c
 set to zero.
 .PP
+Output flushing at fixed intervals may be enabled with the
+.I \-x
+option, which specifies the number of records
+(-c accumulations) before each flush.
+If the
+.I \-y
+option is also set, then periodic flushing is disabled and the
+output size for an RGB image is the taken from the x and y dimensions.
+In lieu of periodic flushing, a flush may be forced as mentioned above
+by sending a sample with a zero direction vector, although you
+must still send a full record of rays before output occurs.
+.PP
 If progress reports are desired, the
 .I \-t
 option specifies a time interval in seconds for reports sent to
 standard error.
+This requires that the number of input samples is known, meaning a
+.I \-y
+parameter has been specified.
 .PP
 The output of
 .I rcontrib
@@ -309,7 +324,7 @@ density estimates results in omitted contributions, th
 is clamped accordingly and a warning is issued. 
 .SH EXAMPLES
 To compute the proportional contributions from sources modified
-by "light1" vs. "light2" on a set of illuminance values:
+by "light1" vs. "light2" on a set of irradiance values:
 .IP "" .2i
 rcontrib \-I+ @render.opt \-o c_%s.dat \-m light1 \-m light2 scene.oct < test.dat
 .PP
@@ -325,7 +340,7 @@ of light1 and light2:
 .IP "" .2i
 pcomb \-c 100 90 75 c_light1.hdr \-c 50 55 57 c_light2.hdr > combined.hdr
 .PP
-To compute an array of illuminance contributions according to a Tregenza sky:
+To compute an array of irradiance contributions according to a Tregenza sky:
 .IP "" .2i
 rcontrib \-I+ \-f tregenza.cal \-b tbin \-bn Ntbins \-o sky.dat \-m skyglow
 \-b 0 \-o ground.dat \-m groundglow @render.opt scene.oct < test.dat