Menus and Toolbar
All the features and functions of CastCor can be accessed either from the Tools menu or from the main toolbar buttons.
opens any of the supported image files.
saves the treated right-hand sample image to a new file at full resolution.
the white point of an image automatically to that of the lightest area
of the image. Choosing this option shifts all the colours of the image
so that a colour cast which is usually caused by an incompatibility
between film or digital camera setting and the illuminating light is
permits choosing the white point manually from the original image.
Click on the left image after clicking on the button or choosing Manual White Point from the Tools menu.
This will display a portion of the image at full size. You can zoom
into or out of the image with the left and right mouse buttons or with
the mouse wheel if there is one. You can move to different parts of the
image either by dragging on it with the left mouse button held down, or
with the scroll bars on the right and bottoms sides. When you have
reached a point which you want to be displayed as white, hold down the Shift key, and a little + marker will appear above and to the right of the cross-cusor. Then, click on the point of interest.
The program will search for the lightest point within ± 2 pixels
of the mouse position and use this as the white point for the image.
To turn off the
manual white point zoomed left window, re-click on the manual white
point button or on the entry in the Tools menu.
You can also use the manual white point option to correct illumination problems. For example, in this image:
Tungsten lamp illumination in a museum display could not be corrected
using the automatic setting of the white point in a digital camera.
Choosing a known white area here permits reasonably good compensation.
the average gray point of an image automatically. This correction is
similar to the white point correction, but it corrects for casts which
are caused by factors other than the colour of the illuminating light.
sets the contrast range of an image to the full range available. It may increase or decrease the contrast as required.
starts the Automatic Color Equalization (ACE) algorithm of Rizzi et. al. This takes some time. Progress is shown with a moving green bar on the little gauge at the bottom of the main dialog.
enhances detail in the highlight and shadow regions of the picture
using a modified Retinex algorithm, leaving the middle tone range
sharpens a blurred image without introducing computational artefacts into large areas of constant colour.
converts a coloured image to greyscale. This may be used if all else fails.
is the Zoom button, corresponding to Zoom
on the main menu. It dispays a little magnifying glass as a
cursor in the left window. Moving this shows the full scale image in
the right window. Movement of the magnifying cursor moves the image in
the right window. Clicking on a point in an area of interest updates
the right window. All operations may now be tried on this area to
observe their effects as full scale. You can restore the image prior to
the zoom operation without losing previous changes by right-clicking on
the right image when it is zoomed. However:
All operations are
based on the statistics of the image visible in the right-hand window.
When you click on the Zoom button, a window into the original image
will be opened there. Since the statistics of this window differ from
those of the normal full-view window, it is strongly advised to use the zoom first before carrying out any operations, so that when the image is finally saved, all the changes will be consistent.
is the Undo button, corresponding to Undo
on the main menu. It restores the previous state of the right image and
the settings of all the parameter trackbars to their previous values.
An unlimited number of undo operations is available. For convenience, a
larger undo button is also available on the central panel:
displays the help
or from the main Help menu, you can click on About to contact the author of the programme.
or Alt-F4 or Exit from the File menu permits you to close the programme.
The original right image can be restored by clicking on the Reset button:
Caution: all changes are lost when this button is pressed.
All operations are
applied only to the small right-hand image, but not to the original
input file. If you have carried out a number of treatment steps in
sequence, the green gauge at the bottom of the programme's dialog will
display the progress of treatment on the full-sized image. Only after
this has been completed will you be asked to provide a name for saving
after you open the Save dialog and save either to the original
file, thus overwriting it (not recommended), or to a file with a new
+name which you must choose.
If you continue
working on the same image and save again, all the changes applied since
the input file was opened will be applied to the output. If you want to
clear the change stack and start again, click the Reset button. You don't have to reload the original file.
There is no
preferred order for doing things. It depends entirely on one's
subjective judgement of the appearance of the image. The unlimited undo
option has been implemented to permit re-tracing one's steps and trying
something else. Most images with colour cast respond best to ACE, and
many images from digital cameras with loss of detail in dark or light
areas respond best to Retinex, but there is no hard and fast rule about
this. The separate colour sliders are mainly useful for a final
"tweaking" to obtain a desired appearance. Please note that unless you
have calibrated your scanner, monitor and printer using specialized
soft- and hardware, printed results may look different from what was
seen on the display.