Page 412 - Xara Designer Pro X17

412 The Photo Tools

the new mapping. So, for example, increasing the brightness or gamma control will
change the line like this;

You can see now that it's no longer a straight line mapping, and that the darker input
shades will be mapped to corresponding lighter output shades.

Using one of the low contrast examples above, this is the altered histogram, showing the
before, after and altered green mapping function line.

You can see the black and white points are moved inwards. This is reflected in the green
line which shows that mid-shades are now mapped to dark, and the lightest white points
(about 80% along the horizontal) are now mapped to white. Thus the narrow range of
input shades is mapped to the full dark-to-light range of output shades.
Output Levels

The two lower controls adjust the minimum (black) and maximum (white) final output
levels. Adjusting these has the effect of reducing the contrast.

Tip: It is usually recommended that for printing purposes the photos do not contain pure
white, but instead have a maximum "whiteness" of around 90%, especially when printed
in black and white. The histogram makes it easy to see if there is a lot of pure white
(peaks at the far right end), and by adjusting the white output level slider you can easily
control this.