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.

sets 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 reduced.

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.

Illumination Correction:

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.

sets 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.

greatly enhances detail in the highlight and shadow regions of the picture using a modified Retinex algorithm, leaving the middle tone range unaffected.

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.