How do I use the CRI Micro Color filter with Openlab?

Technical Note: 19
Reads: 7303
Creation Date: 30/11/1999
Modification Date: 12/02/2004

Before commencing you must check that the CRI filter is properly connected and assigned in the Openlab serial port preferences.

The microscope settings must be optimised for transmitted light microscopy. When using the CRI Micro Color filter you must avoid changing the color temperature of the transmitted light source.

The CRI Micro Color filter is controlled via the Openlab Filterwheel palette. See the Technical note "How do I add filters to my Filterwheel palette" for instructions on editing filters.

The Filterwheel palette should be set for Red (650nm), Green (520nm) and Blue (450nm) colors, ensuring that the filter positions in the palette correspond to the Red, Green and Blue lights on the front of the CRI controller.

In order to achieve the same image intensity for each filter, the optimum camera exposure for each of the filters must now be measured.

Select the Blue filter in the Filterwheel palette.

Move the microscope slide to an area of background.

Using the video controls palette, set the colorisation slider to display pixels within 5 levels of the maximum and minimum values, this will allow pixels in the image that are close to saturation to be easily recognised. Now using the exposure slider adjust the exposure such that the image is just below saturation, ie no red pixels are visible in the image.

Using the HSI Colorspy palette, choose an area of the image and note the pixel intensity value.

Note the value displayed on the exposure slider.

Now select the Red filter and adjust the exposure again until the pixel intensity under the cursor as denoted by the HSI Colorspy is the same value as it was for the Blue filter and note this exposure value.

Repeat this procedure for the Green filter.

Note: return the colorisation slider back to 0 before starting any image acquisition.

You will now have three exposure values, one for each filter. Now calculate the exposure values for the red and green colors relative to the blue exposure. If you are using the CRI RGB automation to acquire the images (this automation is located on the Openlab CD, in the "Automator Menu Items" folder), you will need to enter the relative exposures for the Red, Green and Blue filters by double clicking on the exposure tasks.