diff --git a/fw/Makefile b/fw/Makefile
index 365acd2..04df26c 100644
--- a/fw/Makefile
+++ b/fw/Makefile
@@ -30,7 +30,7 @@ OBJCOPY = $(AVR_PREFIX)objcopy
 #OBJDUMP = $(AVR_PREFIX)objdump
 SIZE = $(AVR_PREFIX)size
 
-OBJS = $(NAME).o dispatch.o hash.o reset.o sweep.o $(COMMON_OBJS)
+OBJS = $(NAME).o dispatch.o hash.o image.o reset.o sweep.o $(COMMON_OBJS)
 BOOT_OBJS = boot.o flash.o fw.o $(COMMON_OBJS)
 COMMON_OBJS = rf.o spi.o
 
diff --git a/fw/image.c b/fw/image.c
new file mode 100644
index 0000000..975fdc1
--- /dev/null
+++ b/fw/image.c
@@ -0,0 +1,17 @@
+/*
+ * fw/image.c - Image data (upload and conversion)
+ *
+ * Written 2012 by Werner Almesberger
+ * Copyright 2012 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#include "image.h"
+
+
+extern struct line image[MAX_LINES];
diff --git a/fw/image.h b/fw/image.h
new file mode 100644
index 0000000..972eba0
--- /dev/null
+++ b/fw/image.h
@@ -0,0 +1,32 @@
+/*
+ * fw/image.h - Image data (upload and conversion)
+ *
+ * Written 2012 by Werner Almesberger
+ * Copyright 2012 Werner Almesberger
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+
+#ifndef IMAGE_H
+#define	IMAGE_H
+
+#include <stdbool.h>
+#include <stdint.h>
+
+
+#define	MAX_LINES	100
+
+
+struct line {
+	uint8_t d;		/* port D0-D7 */
+	uint8_t cb;		/* port C0-C5, B6-B7 */
+};
+
+
+extern struct line image[MAX_LINES];
+
+#endif /* !IMAGE_H */
diff --git a/fw/sweep.c b/fw/sweep.c
index 94ca0d2..0a09d0c 100644
--- a/fw/sweep.c
+++ b/fw/sweep.c
@@ -17,6 +17,7 @@
 #include <avr/io.h>
 #include <avr/interrupt.h>
 
+#include "image.h"
 #include "sweep.h"
 
 
diff --git a/fw/sweep.h b/fw/sweep.h
index 33eb36a..564976e 100644
--- a/fw/sweep.h
+++ b/fw/sweep.h
@@ -18,15 +18,6 @@
 #include <stdint.h>
 
 
-#define	MAX_LINES	100
-
-
-struct line {
-	uint8_t d;		/* port D0-D7 */
-	uint8_t cb;		/* port C0-C5, B6-B7 */
-};
-
-
 struct sweep {
 	uint32_t wait_ticks;	/* number of ticks to wait before image */
 	uint16_t pixel_ticks;	/* number of ticks per pixel */
@@ -36,9 +27,6 @@ struct sweep {
 };
 
 
-extern struct line image[MAX_LINES];
-
-
 void image_sweep(const struct sweep *sweep);
 void sweep_init(void);