For an image of unsigned bytes, how can it be contrast-reversed?

- negate each pixel
- subtract 255 from each pixel
- subtract each pixel from 127
subtract each pixel from 255

In OpenCV, if Y indexes lines, X columns and C channels, the right nesting >of loops is

C inside X inside Y

- X inside Y inside C
- Y inside X inside C
- C inside Y inside X

In the HSV colour space, the complementary colour of green is:

- cyan
magenta

- blue
- yellow

Histogram equalization involves:

- using the inverse of the histogram as a look-up table
- using the histogram as a look-up table
using the cumulative histogram as a look-up table

- using the reciprocal of the histogram as a look-up table

After contrast-stretching, an over-exposed image which has only a few grey levels occupied will have a histogram that

- has a nice peak of grey levels in its middle region
- has all grey-level bins roughly equally occupied
- has a concentration of large values near high grey-level values
tends to show small spikes across the entire range of grey levels

An image which is under-exposed will have a histogram that

- has no significant peaks
- has a peak towards the middle
- has a peak at high grey-level values
has a peak at low grey-level values

OpenCV was initially developed in

Russia

- UK
- Australia
- USA

What is plotted along the abscissa (x-axis) of a histogram?

- mean value
grey level

- standard deviation
- number of occurrences

What is contrast stretching?

- the range of grey level values
- re-scaling the data to a given mean and standard deviation
expanding the available grey levels to fill the range used for displaying images

- the standard deviation

With additive colours, yellow is a mixture of

- blue and green
- cyan and red
- red and cyan
red and green