add shift to zero filter

Fonderie/crapulator.c

@@ -514,6 +514,11 @@ switch (idFx) {
 		retval = fimg_to_gray(image);
 		break;
 
+	case CR_shift0:
+		/* added Sun Sep 29 16:55:54 UTC 2024 */
+		retval = fimg_auto_shift_to_zero(image, image);
+		// fprintf(stderr, "******** Shift Zero -> %d\n", retval);
+		break;
 
 	default :
 		fprintf(stderr, "%s : effect #%d invalid\n", 

Fonderie/crapulors.liste

@@ -47,5 +47,6 @@
 80	thermocol	1	0
 81	triptyq		1	0
 90	togray		1	0
+91	shift0		1	0
 -1	end		1	1.0