Height:
<input id="image_height" value="300" maxlength="4" size="4" type="number"
onchange="checkISValue(this, 'dim'); recalcCoord('Cr', 'scale');">
-<input type="checkbox" id="proportional" onchange="checkProportions();">
+<input type="checkbox" id="proportional" checked="true"
+ onchange="checkProportions();">
<label for="proportional">proportional</label>
<br><br>Maximum of iterations: