diff --git a/doc/the_floatimg_hack.tex b/doc/the_floatimg_hack.tex
index 74f35aef..21b3694b 100644
--- a/doc/the_floatimg_hack.tex
+++ b/doc/the_floatimg_hack.tex
@@ -295,10 +295,21 @@ usage : fimgstats [options] file.fimg
 Operations diverses sur ou entre des images.
 
 \begin{verbatim}
-Usage:
+usage:
         fimgops [options] A.fimg B.fimg operator D.fimg
+operators:
+        add             1
+        sub             2
+        mix             3
+        mul             4
+options:
+        -g              convert output to gray
+        -k N.N          set float value
+        -v              increase verbosity
 \end{verbatim}
 
+Pour l'operateur \texttt{mix}, le paramêtre flottant doit
+être fourni en utilisant l'option \texttt{-k}.
 
 \subsection{fimg2png, fimg2pnm, fimg2tiff}
 		\index{fimg2png}\label{fimg2png}
diff --git a/tools/fimgops.c b/tools/fimgops.c
index e3e17b56..75211b71 100644
--- a/tools/fimgops.c
+++ b/tools/fimgops.c
@@ -7,9 +7,14 @@
 
 int		verbosity;
 
+/* --------------------------------------------------------------------- */
+
+float		global_fvalue;
+
 /* --------------------------------------------------------------------- */
 #define		OP_ADD		1
 #define		OP_SUB		2
+#define		OP_MIX		3
 #define		OP_MUL		4
 typedef struct {
 	int	code;
@@ -19,6 +24,7 @@ typedef struct {
 Opcode opcodes[] = {
 	{ OP_ADD,		"add"		},
 	{ OP_SUB,		"sub"		},
+	{ OP_MIX,		"mix"		},
 	{ OP_MUL,		"mul"		},
 	{ 0,			NULL		}
 	};
@@ -27,7 +33,7 @@ static void pr_opcodes(void)
 Opcode *optr;
 puts("operators:");
 for (optr = opcodes; optr->code; optr++) {
-	printf("\t%-20s %d\n", optr->op, optr->code); 
+	printf("\t%-15s %d\n", optr->op, optr->code); 
 	} 
 }
 static int look_opcode(char *txt)
@@ -52,6 +58,10 @@ static void help(int lj)
 
 puts("usage:\n\tfimgops [options] A.fimg B.fimg operator D.fimg");
 pr_opcodes();
+puts("options:");
+puts("\t-g              convert output to gray");
+puts("\t-k N.N          set float value");
+puts("\t-v              increase verbosity");
 if (verbosity) fimg_print_version(1);
 exit(0);
 }
@@ -66,6 +76,11 @@ switch (action)	{
 		foo = fimg_add(A, B, D);		break;
 	case OP_SUB:
 		foo = fimg_sub(A, B, D);		break;
+	case OP_MIX:
+		if (verbosity) fprintf(stderr, "fvalue is %f\n",
+							global_fvalue);
+		foo = fimg_interpolate(A, B, D, global_fvalue);
+		break;
 	case OP_MUL:
 		foo = fimg_add(A, B, D);		break;
 	default:
@@ -79,7 +94,6 @@ return foo;
 int main(int argc, char *argv[])
 {
 int		foo, opt, action;
-float		fvalue;
 char		*operator;
 
 FloatImg	srcA, srcB, dest;
@@ -87,7 +101,7 @@ FloatImg	srcA, srcB, dest;
 while ((opt = getopt(argc, argv, "hk:v")) != -1) {
 	switch(opt) {
 		case 'h':	help(0);			break;
-		case 'k':	fvalue = atof(optarg);		break;
+		case 'k':	global_fvalue = atof(optarg);	break;
 		case 'v':	verbosity++;			break;
 		}
 	}
@@ -141,7 +155,8 @@ foo = fimg_create(&dest, srcA.width, srcA.height, srcA.type);
 
 foo = exec_operator(&srcA, &srcB, action, &dest);
 if (foo) {
-	fprintf(stderr, "operator exec give us a %d\n", foo);
+	fprintf(stderr, "operator '%s' exec give us a %d\n",
+					operator, foo);
 	}
 
 foo = fimg_dump_to_file(&dest, argv[optind+3], 0);