What is the process to calibrate the DAS?

These following calibrations should be executed in the following order:

1. Position calibration, which calibrates the position of the cups in an image.

2. Uniformity calibration, which calibrates the distribution of the illumination.

3. Color calibration, which calibrates the observed colors by the DAS.

See below for details:

1) Position calibration: 

During the incubation run, the DAS creates images. The location of the plate and its cups in an image needs to be calibrated. The position calibration test can find the location of the cups by taking two images: 1) without plate 2) with plate. The second image is with a plate and it should be un-incubated plate. The actions to execute the position calibration are shown during the execution of the calibration. The position calibration has the following steps:

1. Put DAS in service mode by long pressing ( > 10 seconds) on the gear button on the DAS.

2. Confirm that no plate is the DAS

3. Place a black/dark* matte sheet of paper or cloth on top of heating grid and close DAS lid. Black face should be facing downwards. *Can be made by copier machine with ‘open’ lid.

Refer to "White and Black targets for DAS calibrations" for details on the black card.  

4. Start first step calibration without plate,

Note: between the steps, the DAS needs to perform some calculations and a progress bar will be shown.

5. In next step, place un-incubated plate in grid (cover with black paper) and close lid

6. Verify the calibration result and activate result

The Figure below shows a screenshot of step 4 of the position calibration. During step 4 the number of found cups and their location is verified and the result is presented. If the found cup location looks correct, activate the calibration result by pressing on the Activate button.

After the execution of the position calibration, some post actions need to be performed, such as removal of the plate. These actions will be shown after the test. The calibration creates a new folder in the folder “Calibration” with as name Position-date-time. This folder will contain the following files:

• Pdf-file “Devicename_Position-Date-time.pdf” with the calibration report, saved also on the backup server (see also 'save files to Network"' 

• Txt-file “CalibratedCellPosition.txt” with the raw calibration result

• Two captured images and a result image with the found cup locations

2) Uniformity

During the incubation run, the plate is illuminated, and images are created. The distribution of the illumination needs to be calibrated by captured images from a (uniform) bright white* sheet of paper. Refer to "White and Black targets for DAS calibrations" for details on the white card.  

* Alternative use high quality dull/mat photo paper 10x15 cm, assure ‘DAS-window’ is fully covered.

The actions to execute the uniformity calibration are shown during the execution of the calibration. The uniformity calibration has following steps:

1. Put DAS in service mode by long pressing (> 10 seconds) on the gear button on the DAS.

2. Remove the heating grid and verify that the glass plate of the DAS is clean.

3. Place white paper sheet (dimensions are 155 x 130 mm).

4. Place back the heating grid and close the lid.

5. Verify the calibration result and activate the result by pressing on the Activate button.

The calibration result is verified by DAS by several checks* and most important checks are shown (see Figure for an example). *Some color channels checks are not shown on result screen.

The calibration creates a new folder in the folder “Calibration” with as name Uniformity-date-time. This folder will contain the following files:

• Pdf-file “Devicename_Uniformity-Date-time.pdf” with the calibration report, saved also on the backup server

• Txt-file “UniformityGain.txt” with the raw calibration result

• Several captured images with various exposure times

3) Color

The observed colors by the DAS need to be calibrated to ensure that the results of between various DAS devices are comparable. This color calibration is based on a captured image from a (Macbeth) color card from which the measured colors have been accurately measured. It is advised to use the color card (dimensions are 120 x 83 mm) produced by Cameratrax (see Figure below). With this color card the measured colors (SRGB) are printed under the colored tiles. The color calibration requires that these values are stored in color card definition file (see datafile below for an example). The serial numbers of the color card and the color card definition file should match with each other. The color card definition file is supplied by DSM and can be loaded via the Setup page. See also "What features can be set up in the DAS?".

The actions to execute the color calibration are shown during the execution of the calibration. The color calibration has four steps:

1. Put DAS in service mode by long pressing (> 10 seconds) on the gear button on the DAS.

2. Remove the heating grid and verify that the glass plate of the DAS is clean.

3. Verify if the serial number of the color card is the same as the used color card definition file. Place the color card in the center of the window.

4. Verify the calibration result and activate the result by pressing on the Activate button With the verification of the calibration result is checked if the found number of tiles is 24 and if the fitting error (standard deviation) is good enough. 

The calibration creates a new folder in the folder “Calibration” with as name AbsoluteColor-date-time. This folder will contain the following files:

• Pdf-file “Devicename_AbsoluteColor-Date-time.pdf” with the calibration report, saved also on the backup server

• Txt-file “AbsoluteColorCalibration.txt” with the raw calibration result

• Captured raw image and image with corrected colors

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