diff --git a/lib/Makefile b/lib/Makefile
index ea2e3d4..ac58414 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -2,7 +2,7 @@
 #	building the base library
 #
 
-COPT = -Wall -fpic -g -no-pie -DDEBUG_LEVEL=0
+COPT = -Wall -fpic -g -no-pie -DDEBUG_LEVEL=1
 OBJS = fimg-core.o fimg-pnm.o fimg-file.o fimg-math.o	\
 	fimg-timers.o operators.o fimg-2gray.o		\
 	interpolate.o fimg-compare.o contrast.o
diff --git a/lib/runme.sh b/lib/runme.sh
new file mode 100755
index 0000000..89144e7
--- /dev/null
+++ b/lib/runme.sh
@@ -0,0 +1,19 @@
+#!/bin/bash
+
+make t && ./t
+
+for picz in src power2 squareroot
+do
+
+	../tools/fimgstats -v ${picz}.fimg
+	../tools/fimg2pnm -v ${picz}.fimg ${picz}.pnm
+
+	convert -pointsize 36			\
+		-fill white -annotate +10+28 "${picz}" 			\
+		-fill black -annotate +12+30 "${picz}" 			\
+		${picz}.pnm ${picz}.png
+
+done
+
+convert -delay 50 *.png foo.gif
+
diff --git a/lib/t.c b/lib/t.c
index 4ed6fb7..3558594 100644
--- a/lib/t.c
+++ b/lib/t.c
@@ -71,20 +71,27 @@ return 0;
 int essai_contraste(char *fname)
 {
 int		foo;
-FloatImg 	dessin;
+FloatImg 	dessin, copy;
 double		maxi;
 
 foo = fimg_create_from_dump(fname, &dessin);
 
-maxi = (double)fimg_get_maxvalue(&dessin);
-fprintf(stderr, "avant    valeur maxi = %f\n", maxi);
+foo = fimg_clone(&dessin, &copy, 0);
 
-fimg_power_2(&dessin, NULL, maxi);
 
 maxi = (double)fimg_get_maxvalue(&dessin);
-fprintf(stderr, "apres    valeur maxi = %f\n", maxi);
+fprintf(stderr, "avant  power_2  valeur maxi = %f\n", maxi);
+
+fimg_power_2(&dessin, &copy, maxi);
+maxi = (double)fimg_get_maxvalue(&dessin);
+fprintf(stderr, "apres  power_2  valeur maxi = %f\n", maxi);
+fimg_dump_to_file(&copy, "power2.fimg", 0);
+
+fimg_square_root(&dessin, &copy, maxi);
+maxi = (double)fimg_get_maxvalue(&dessin);
+fprintf(stderr, "apres  square_root  valeur maxi = %f\n", maxi);
+fimg_dump_to_file(&copy, "squareroot.fimg", 0);
 
-fimg_dump_to_file(&dessin, "dst.fimg", 0);
 
 fimg_destroy(&dessin);