GIMP tools - BDA

GIMP 32
In this mode, each point has from 0 to 255 level of brightness. Values between black and
white are different levels of grey.
These two image modes differ in terms of the number of colour channels. RGB has
three channels, grayscale – one and that is why such image takes three times less space.
INDEXED COLOURS
The number of colours in these images is limited, i.e. no more than 256, to save the
random-access memory. Indexed colours are not something new. These formats were
created a decade ago when computers had small random-access memories. Although
now they are rarely used, they are supported by GIMP as it is easier to perform certain
actions with this kind of image than with the RGB-colour image.
GIF and PNG are indexed formats. Even though GIMP supports them, certain filters
cannot work on such images because they have only a limited number of colours. If such
filter is necessary, the image is transformed into a RGB model, filtered and then
returned to the indexed image. To change the colour mode, use the command
ImageMode.
You should remember that switching between formats results in losing some of the
information which will not be restored when switching back. For example, if you go from
RGB to grayscale, the information on the colour is lost, so when you return to RGB, the
image remains black-and-white.
GIMP tools
Capabilities of tools
GIMP tools carry out many tasks. They are grouped into five groups:
1) selection tools specify the portion of the image that will be affected by
subsequent actions;
2) paint tools alter colours in some part of the image;
3) colour tools alter the distribution of colours across the entire image;
4) transform tools alter the geometry of the image;
5) other tools, which do not fall into the groups above.
Tools may be activated in one of the following ways:
1) by clicking on an icon in the Toolbox;
2) from the Tools menu;