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Nero PhotoSnap Nero PhotoSnap • 23
The preview will show you the image after using the automatic adjustment
feature.
4. Click on the 'Apply' button to conduct automatic adjustment. v
3.3.3 Exposure
The CCD chips used in digital cameras, record images by measuring the
brightness of each pixel and depicting the brightness as a numerical value.
Usually, values between 0 and 255 (i.e. 8 bit) are saved for each color
component (red, green or blue). Where possible, the brightness in the subject
being photographed should match the range that can be achieved by the sensor,
so as to achieve optimum picture quality.
When post editing a digital photograph it thus makes sense to check which
brightness values the sensor can record. A so-called histogram is used to assist.
The brightness values which can generally be achieved in the picture are
displayed on the horizontal (X) axis, while the vertical (Y) axis shows the number
of pixels with their respective brightness values. Graphically displayed, this
provides a kind of "mountain range", which tells you at a glance whether the
image is already of a good quality or whether it may need post editing.
The histogram and its importance for post editing:
a. The histogram contains a "mountain" on the left-hand side, whereas the right-
hand side does not display any upward deflection or is very flat. A picture like this
is underexposed. In order to correct this digital photograph, the histogram must
be (figuratively speaking) "stretched" to the right so as to cover the entire
brightness range.