Oldal 69 [69]
Display mode
Select the option to show the RGB Histogram, if this is available.
The histogram is a useful guideline to assess the exposure of an image. It is a simple
graphical representation of data collected. Digital images are made up of millions of tiny
square pixels. In every 8 bit digital image each pixel is assigned a brightness value between
0 and 255. The camera scans each pixel and adds up how many pixels there are at each
brightness level. Then it translates that into a frequency graph called a histogram. On the
horizontal axis 0 at the left of the histogram represents pure black and 255 at the right is
pure white. The vertical axis shows the number of pixels recorded at that brightness value or
frequency. The more pixels at a specific brightness value, the higher the line.
It should be noted however, that the on-camera histogram shows the histogram of the in¬
camera conversion to J] PEG (see Chapter 3) and not that pertaining to the RAW data, and
as most cameras apply a fairly strong S-curve to the RAW data so that the J PEGs have a
more film-like response, the result is that the on-camera histogram often suggests that the
highlights in the image are saturated when, in fact, they are still comfortably in the range.”
Summary
General camera Settings:
RAW (check RAW file will be saved by and exported from the
Image-recording format
camera)
Image quality (bit depth) 16 bit (or highest available)
Colour space SRGB
White balance Set custom white balance if required
Camera mode Manual mode (M)
Picture style (if available) Neutral
Set camera to timer (2 s or 10 s), to avoid camera shake
Self-timer mode ;
during long captures or use a remote release shutter
Display mode Check the RGB Histogram box
vi. Exposure settings
The settings for the following parameters determine the exposure of the image and will
depend on the type of object being imaged and the type of imaging being carried out.
Exposure is determined by three camera settings: ISO speed, aperture (F-stop), and shutter
speed (the “exposure triangle"). Below are some general guidelines on setting these
parameters, for more information the reader is referred to designated texts or websites on
photographic techniques and concepts.”
Version No. 1.0 61 Date : 14/10/2013