Fix crash when loi255.loi is loaded

app/Operations/Quantification.h

@@ -22,6 +22,8 @@
 
 #include <Image.h>
 
+#define N_MAX_THRESHOLD 256
+
 struct Quantification {
     static Quantification linearQuant(int size);
     static Quantification nonLinearQuant(int size, const imagein::Image *image, unsigned int c);

app/Operations/QuantificationWidget.h

@@ -25,7 +25,7 @@
 
 #include <QScrollArea>
 #include "Quantification.h"
-#define N_MAX_THRESHOLD 32
+
 class QuantificationWidget : public QScrollArea
 {
     Q_OBJECT